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## 2019 Nobel Prize in Chemistry

Originally published in Physics Today by Alex Lopatka

John Goodenough, M. Stanley Whittingham, and Akira Yoshino will receive the 2019 Nobel Prize in Chemistry for developing lithium-ion batteries, the Royal Swedish Academy of Sciences announced on Wednesday. Goodenough (University of Texas at Austin), Whittingham (Binghamton University in New York), and Yoshino (Asahi Kasei Corp and Meijo University in Japan) will each receive one-third of the 9 million Swedish krona (roughly $900 000) prize. Their research not only allowed for the commercial-scale manufacture of lithium-ion batteries, but it also has supercharged research into all sorts of new technology, including wind and solar power. At the heart of any battery is a redox reaction. During the discharge phase, the oxidation reaction at the anode frees ions to travel through a liquid electrolyte solution to the cathode, which is undergoing a reduction reaction. Meanwhile, electrons hum through a circuit to power a connected electronic device. For the recharge phase, the redox processes reverse, and the ions go back to the anode so that it’s ready for another discharge cycle. The now ubiquitous lithium-ion battery that powers smartphones, electric vehicles, and more got its start shortly before the 1973 oil crisis. The American Energy Commission asked Goodenough, who was then at MIT’s Lincoln Laboratory, to evaluate a project by battery scientists at the Ford Motor Company. They were looking into the feasibility of molten-salt batteries, which used sodium and sulfur, to replace the standard but outdated lead–acid batteries developed about a century earlier. But by the late 1960s, it became clear that high operating temperatures and corrosion problems made those batteries impractical (see the article by Matthew Eisler, Physics Today, September 2016, page 30). Whittingham, then a research scientist at Exxon, instead considered low-temperature, high-energy batteries that could not only power electric vehicles but also store solar energy during off-peak hours. To that end he developed a battery in 1976 with a titanium disulfide cathode paired with a lithium metal anode. Lithium’s low standard reduction potential of −3.05 V makes it especially attractive for high-density and high-voltage battery cells. Critically, Whittingham’s design employed lithium ions that were intercalated—that is, inserted between layers of the TiS2 structure—and provided a means to reversibly store the lithium during the redox reactions. Lithium’s high reactivity, however, means that it must be isolated from air and water to avoid dangerous reactions. Whittingham solved that problem by using nonaqueous electrolyte solutions that had been carefully designed and tested by other researchers in lithium electrochemistry experiments conducted a few years earlier. The proof of concept was a substantial improvement: Whittingham’s lithium-ion battery had a higher cell potential than the lead–acid battery’s—2.5 V compared with 2 V. Whittingham’s lithium-ion battery, though, wasn’t particularly stable. After repeated discharging and recharging, whisker-like crystals of lithium would grow on the anode. Eventually the wispy threads would grow large enough to breach the barrier separating the anode from the cathode, and the battery would short-circuit or even explode. In 1980 Goodenough didn’t solve that problem, but he did come up with a much better material for the cathode. Along with Koichi Mizushima and colleagues at Oxford University, he found that lithium cobalt oxide could be used for the cathode. As with the TiS2, the cobalt oxide structure was tightly intercalated with lithium and could thus provide the cathode with sufficient energy density. Goodenough’s insight into the relationship between the cobalt oxide structure and voltage potential resulted in better battery performance; the voltage increased from 2.5 V to 4 V. Although the new battery was an improvement over Whittingham’s design, the system still used highly reactive lithium metal as the anode, so companies couldn’t safely manufacture the batteries on a commercial scale. The final piece of the puzzle fell into place in 1985 when Yoshino, working at the Asahi Kasei Corp, replaced the anode material with graphite. It was stable in the required electrochemical conditions and accommodated many lithium ions in graphite’s crystal structure. With Goodenough’s lithium cobalt oxide cathode and the graphite anode, Yoshino, “came up with two materials you could put together without a glove box” in a chemistry laboratory, says Clare Grey, a chemist at the University of Cambridge. Importantly, the graphite anode is lightweight and capable of being recharged hundreds of times before its performance deteriorates. Soon after, Sony teamed up with Asahi Kasei and replaced all the nickel–cadmium batteries in its consumer electronics with lithium-ion ones. “The story of the lithium-ion battery, like so many stories about innovation, is about contributions from many sources over many years, conditioned by changing economic and social circumstances,” says Matthew Eisler, a historian of science at the University of Strathclyde in Glasgow, UK. When the 1979 oil crisis ended, the automotive industry’s interest in batteries drained, but in 1991 they were commercialized for use in cameras, laptops, smartphones, and other handheld electronics enabled by advancements in microprocessor technology. To develop transportation that doesn’t rely on fossil fuels, the US Department of Energy in 2013 set an ambitious goal for its Joint Center for Energy Storage Research: Make a battery for electric vehicles that has five times the energy density and is one-fifth the cost of currently available batteries. DOE’s goal hasn’t been reached yet, but the program was renewed in September 2018, with dedicated funding of$120 million over the next five years. In a story on the center, Goodenough told Physics Today (June 2013, page 26), “People are working hard, and I believe the problem is solvable, but to get to the next stage, it’s going to take a little luck and some cleverness.”

Editor’s note: This post was updated at 7:15pm EDT from an earlier summary.

## 2019 Nobel Prize in Physics

This is a reblog go the post in Physics Today, written by Andrew Grant.

The researchers are recognized for their contributions to theoretical cosmology and the study of extrasolar planets.

James Peebles, Michel Mayor, and Didier Queloz will receive the 2019 Nobel Prize in Physics for helping to understand our place in the universe through advances in theoretical cosmology and the detection of extrasolar planets, the Royal Swedish Academy of Sciences announced on Tuesday. Peebles is a theoretical cosmologist at Princeton University who helped predict and then interpret the cosmic microwave background (CMB) and later worked to integrate dark matter and dark energy into the cosmological framework. Mayor and Queloz are observational astronomers at the University of Geneva who in 1995 discovered 51 Pegasi b, the first known exoplanet to orbit a Sunlike star. Peebles will receive half of the 9 million Swedish krona (roughly $900 000) prize; Mayor and Queloz (who also has an appointment at the University of Cambridge) will share the other half. The contributions of Peebles and of Mayor and Queloz helped jumpstart their respective fields. Over the past few decades, researchers have developed the successful standard model of cosmology, Lambda CDM, though the nature of both dark energy and dark matter remains an open question. Meanwhile, astronomers have used the radial velocity technique employed by Mayor and Queloz, along with the transit method and even direct imaging, to discover and characterize a diverse population of thousands of exoplanets. Data from NASA’s Kepler telescope suggest that the Milky Way harbors more planets than stars. #### Connecting past with present “More than any other person,” writes Caltech theoretical physicist Sean Carroll on Twitter, Peebles “made physical cosmology into a quantitative science.” His contributions began even before Arno Penzias and Robert Wilson’s 20-foot antenna at Bell Labs picked up the unexpected hum of 7.35 cm microwave noise that would come to be known as the CMB. Working as a postdoc with Robert Dicke at Princeton, Peebles predicted in a 1965 paper that the remnant radiation from a hot Big Bang, after eons of propagating through an expanding universe, would have a temperature of about 10 K. In a subsequent paper Peebles connected the temperature of the CMB, measured by Penzias and Wilson at 3.5 K (now known to be 2.7 K), to the density of matter in the early universe and the formation of light elements such as helium. In 1970 Peebles and graduate student Jer Yu predicted a set of temperature fluctuations imprinted in the CMB due to the propagation of acoustic waves in the hot plasma of the infant universe. Decades later, the Cosmic Background Explorer (COBE), the Wilkinson Microwave Anisotropy Probe (WMAP), and, most recently, the Planck satellite would measure a similar power spectrum in the CMB. “The theoretical framework that he helped create made testable predictions,” says Priyamvada Natarajan, a Yale theoretical astrophysicist. “They still inform a lot of the observational tests of cosmology.” Peebles also considered the connection between those fluctuations and the large-scale structure of the universe we observe today, as measured through galaxy clusters in sky surveys. “His idea that you can see the initial conditions and dynamics of the universe in the clustering of galaxies transformed what we could do as a community,” says New York University astrophysicist David W. Hogg. Peebles’s view of the CMB and what it embodies proved especially important in the early 1980s, when cosmologists struggled to reconcile the deduced densities of matter in the infant universe with the large-scale structure that ultimately emerged. In a 1982 paper, Peebles proposed a solution in the form of nonrelativistic dark matter. Long after escaping the dense confines of the infant cosmos, that cold dark matter (CDM) would form the cocoons in which ordinary matter clumped into galaxies and then galaxy clusters. His paper built on the work of Vera Rubin, whose measurements with Kent Ford of the rotation curves of the Andromeda galaxy were critical toward demonstrating that dark matter must be the dominant component of galactic halos, to keep disks of stars and gas from flying apart. Subsequent satellite measurements have revealed that collectively dark matter has about five times the mass of ordinary matter. By the 1990s it was becoming clear that a model containing just CDM, ordinary matter, and photons couldn’t account for all the observed properties of the universe, notably the value of the Hubble constant. The result is Lambda CDM, the cosmological model that describes the universe with six precisely measured parameters and accounts for the 1998 discovery that the universe’s expansion is accelerating. Peebles was one of the theorists to propose resurrecting Albert Einstein’s once-discarded cosmological constant to describe the newly discovered dark energy, which makes up more than two-thirds of the mass–energy content of the universe. #### Ushering in the exoplanet era To appreciate the contribution of Mayor and Queloz, consider that in 1995 the least massive known object outside the solar system was a star of 0.08 solar masses; Jupiter, for comparison, is about 0.001 M. Mayor was part of a team that in 1989 reported the probable detection of an object 11 times as massive as Jupiter that could be classified as either a very large planet or a brown dwarf. Pennsylvania State University astronomer Jason Wright says that other teams amassed preliminary evidence of extrasolar planets, but it was unconvincing and led planetary scientist William Cochran to declare, “Thou shalt not embarrass thyself and thy colleagues by claiming false planets.” In 1992 Alexander Wolszczan and his colleagues discovered two planets orbiting the pulsar PSR B1257+12 via timing variations in the dead star’s radio beacon. (A third later found around the same pulsar remains the lowest-mass exoplanet yet discovered.) The discovery showed that exoplanets are out there, but the question remained of how common they are around stars like the Sun, where well-placed ones would presumably have the potential to support life. At the Haute-Provence Observatory in southeastern France, Mayor and his graduate student Queloz conducted a survey of 142 stars using a spectrograph called ELODIE, which they designed to enable the observation of fainter stars than had previously been surveyed. The researchers’ approach, first proposed in 1952 by Otto Struve, was to detect the Doppler shift in the stellar spectrum due to the star’s motion as it is pushed and pulled by an orbiting planet. The expected stellar wobble due to a planet’s tug was on the order of 10 m/s; even now, the best spectrometers have a resolution of about 1000 m/s, Hogg says. Mayor and Queloz needed to be able to pinpoint a shift that accounted for a hundredth, or even a thousandth, of a pixel. That’s exactly what they did through analysis of the signal from 51 Pegasi, a star located about 50 light-years away in the constellation Pegasus. The Doppler shift was consistent with the motion of a Jupiter-mass planet in a four-day orbit at 0.05 astronomical units, far shorter than the distance between Mercury and the Sun. The discovery of a “hot Jupiter” was surprising but also helpful, as the short period enabled Mayor and Queloz, and competing groups, to easily conduct follow-up observations. The astronomers announced their discovery at a conference in Italy almost exactly 24 years ago, on 6 October 1995, and soon published their result in Nature. Another group promptly confirmed the finding. “It’s a discovery that has completely changed our view of who we are,” says Yale University astronomer Debra Fischer. “And it came at a time when we thought that maybe there weren’t many planets around other stars.” However, the astronomy community wasn’t yet convinced by Mayor and Queloz’s claim. Many researchers didn’t think it was possible for such a massive planet to either form so close to the star or migrate inward without getting incinerated. Theorists proposed that the observed stellar wobbles might not be caused by an exoplanet at all, but rather by phenomena such as stellar brightness oscillations. But even the most skeptical came around in 1999, with discoveries of the first multi-exoplanet system by Fischer and colleagues, and of HD 209548 b. That planet was detected via the drop in brightness it caused when it passed in front of its star. The early planet confirmations convinced observatory directors to build and install spectrographs. They also ultimately helped coax NASA to greenlight the development of a space telescope proposal that had been languishing for decades, a mission called Kepler. That satellite, which was launched in 2009, and instruments such as the Transiting Exoplanet Survey Satellite have detected thousands of planets and planet candidates. Nearly a quarter century after Mayor and Queloz’s discovery, exoplanet science is a powerhouse endeavor that engages a significant percentage of the astrophysics community. Researchers join the field to study not only the planets but also the stars they orbit, which in turn has led to new insights in stellar astrophysics. By pairing transit measurements, which determine planets’ radii, with radial velocity, which provides masses, researchers have determined that many of the galaxy’s planets don’t resemble those in our solar system. The lack of resemblance challenges theories of planet formation and extends the range of planetary types that theories have to accommodate. The most tantalizing goal of the field set in motion by Mayor and Queloz is to find planets that resemble Earth and to detect biosignatures. Researchers are already probing the atmospheres of individual worlds using the Hubble Space Telescope and other tools. Next-generation instruments, particularly the James Webb Space Telescope and the Wide Field Infrared Survey Telescope, will aid in that effort. Read me... ## Orion at the Institute of Physics via Instagram http://bit.ly/2DGSPaI It was great to have been able to attend a lecture at the new home of the Institute of Physics. I have been a member for almost two decades and I have even served as an officer for one of the interest groups, the Computational Physics Group is you must know. The event was a talk by Stephen Hilton from the School of Pharmacy, UCL 3D Printing and its Application in Chemistry and Pharmacy. It was a very useful talk covering applications ranging from teaching, cost saving in chemistry labs, personalised medicine and chemistry itself. As for the building, it was nice to finally see the end result, with a hint of brutalist architecture and some nice details such as the electromagnetic wave diagram in some of the windows, and Orion in the cealing! Read me... ## Catching up with some reading - drug discovery and synthetic life Catching up with some reading. Very timely, PhysicsWorld is covering some new developments in high-spec mass spectroscopy and drug discovery. While The Economist's front cover is about synthetic biology. Yay! Soupy twist! Read me... ## The Year in Math and Computer Science A reblog from Quanta Magazine: https://www.quantamagazine.org/quantas-year-in-math-and-computer-science-2018-20181221/ Several mathematicians under the age of 30, and amateur problem-solvers of all ages, made significant contributions to some of the most difficult questions in math and theoretical computer science. Youth ruled the year in mathematics. The Fields Medals — awarded every four years to the top mathematicians no older than 40 — went out to four individuals who have left their marks all over the mathematical landscape. This year one of the awards went to Peter Scholze, who at 30 became one of the youngest ever to win. But at times in 2018, even 30 could feel old. Two students, one in graduate school and the other just 18, in two separate discoveries, remapped the borders that separate quantum computers from ordinary classical computation. Another graduate student proved a decades-old conjecture about elliptic curves, a type of object that has fascinated mathematicians for centuries. And amateur mathematicians of all ages rose up to make significant contributions to long-dormant problems. But perhaps the most significant sign of youth’s rise was when Scholze, not a month after the Fields Medal ceremony, made public (along with a collaborator) his map pointing to a hole in a purported proof of the famous abc conjecture. The proof, put forward six years ago by a mathematical luminary, has baffled most mathematicians ever since. Read me... ## Physics Wold Now reading my monthly issue of "Physics Wolrd". An interesting Focus issue on biomedical physics. This article on developing clinical partnerships is a recommended read. Read me... ## A new Bose-Einstein condensate Originally published here. ## A new Bose-Einstein condensate Although Bose-Einstein condensation has been observed in several systems, the limits of the phenomenon need to be pushed further: to faster timescales, higher temperatures, and smaller sizes. The easier creating these condensates gets, the more exciting routes open for new technological applications. New light sources, for example, could be extremely small in size and allow fast information processing. In experiments by Aalto researchers, the condensed particles were mixtures of light and electrons in motion in gold nanorods arranged into a periodic array. Unlike most previous Bose-Einstein condensates created experimentally, the new condensate does not need to be cooled down to temperatures near absolute zero. Because the particles are mostly light, the condensation could be induced in room temperature. 'The gold nanoparticle array is easy to create with modern nanofabrication methods. Near the nanorods, light can be focused into tiny volumes, even below the wavelength of light in vacuum. These features offer interesting prospects for fundamental studies and applications of the new condensate,' says Academy Professor Päivi Törmä. The main hurdle in acquiring proof of the new kind of condensate is that it comes into being extremely quickly.'According to our theoretical calculations, the condensate forms in only a picosecond,' says doctoral student Antti Moilanen. 'How could we ever verify the existence of something that only lasts one trillionth of a second?' Turning distance into time A key idea was to initiate the condensation process with a kick so that the particles forming the condensate would start to move. 'As the condensate takes form, it will emit light throughout the gold nanorod array. By observing the light, we can monitor how the condensation proceeds in time. This is how we can turn distance into time,' explains staff scientist Tommi Hakala. The light that the condensate emits is similar to laser light. 'We can alter the distance between each nanorod to control whether Bose-Einstein condensation or the formation of ordinary laser light occurs. The two are closely related phenomena, and being able to distinguish between them is crucial for fundamental research. They also promise different kinds of technological applications,' explains Professor Törmä. Both lasing and Bose-Einstein condensation provide bright beams, but the coherences of the light they offer have different properties. These, in turn, affect the ways the light can be tuned to meet the requirements of a specific application. The new condensate can produce light pulses that are extremely short and may offer faster speeds for information processing and imaging applications. Academy Professor Törmä has already obtained a Proof of Concept grant from the European Research Council to explore such prospects. Materials provided by Aalto University. Note: Content may be edited for style and length. Journal Reference: 1 Tommi K. Hakala, Antti J. Moilanen, Aaro I. Väkeväinen, Rui Guo, Jani-Petri Martikainen, Konstantinos S. Daskalakis, Heikki T. Rekola, Aleksi Julku, Päivi Törmä. Bose–Einstein condensation in a plasmonic lattice. Nature Physics, 2018; DOI: 10.1038/s41567-018-0109-9 Read me... ## New quantum method generates really random numbers Originally appeared in ScienceDaily, 11 April 2018. # New quantum method generates really random numbers Researchers at the National Institute of Standards and Technology (NIST) have developed a method for generating numbers guaranteed to be random by quantum mechanics. Described in the April 12 issue of Nature, the experimental technique surpasses all previous methods for ensuring the unpredictability of its random numbers and may enhance security and trust in cryptographic systems. The new NIST method generates digital bits (1s and 0s) with photons, or particles of light, using data generated in an improved version of a landmark 2015 NIST physics experiment. That experiment showed conclusively that what Einstein derided as "spooky action at a distance" is real. In the new work, researchers process the spooky output to certify and quantify the randomness available in the data and generate a string of much more random bits. Random numbers are used hundreds of billions of times a day to encrypt data in electronic networks. But these numbers are not certifiably random in an absolute sense. That's because they are generated by software formulas or physical devices whose supposedly random output could be undermined by factors such as predictable sources of noise. Running statistical tests can help, but no statistical test on the output alone can absolutely guarantee that the output was unpredictable, especially if an adversary has tampered with the device. "It's hard to guarantee that a given classical source is really unpredictable," NIST mathematician Peter Bierhorst said. "Our quantum source and protocol is like a fail-safe. We're sure that no one can predict our numbers." "Something like a coin flip may seem random, but its outcome could be predicted if one could see the exact path of the coin as it tumbles. Quantum randomness, on the other hand, is real randomness. We're very sure we're seeing quantum randomness because only a quantum system could produce these statistical correlations between our measurement choices and outcomes." The new quantum-based method is part of an ongoing effort to enhance NIST's public randomness beacon, which broadcasts random bits for applications such as secure multiparty computation. The NIST beacon currently relies on commercial sources. Quantum mechanics provides a superior source of randomness because measurements of some quantum particles (those in a "superposition" of both 0 and 1 at the same time) have fundamentally unpredictable results. Researchers can easily measure a quantum system. But it's hard to prove that measurements are being made of a quantum system and not a classical system in disguise. In NIST's experiment, that proof comes from observing the spooky quantum correlations between pairs of distant photons while closing the "loopholes" that might otherwise allow non-random bits to appear to be random. For example, the two measurement stations are positioned too far apart to allow hidden communications between them; by the laws of physics any such exchanges would be limited to the speed of light. Random numbers are generated in two steps. First, the spooky action experiment generates a long string of bits through a "Bell test," in which researchers measure correlations between the properties of the pairs of photons. The timing of the measurements ensures that the correlations cannot be explained by classical processes such as pre-existing conditions or exchanges of information at, or slower than, the speed of light. Statistical tests of the correlations demonstrate that quantum mechanics is at work, and these data allow the researchers to quantify the amount of randomness present in the long string of bits. That randomness may be spread very thin throughout the long string of bits. For example, nearly every bit might be 0 with only a few being 1. To obtain a short, uniform string with concentrated randomness such that each bit has a 50/50 chance of being 0 or 1, a second step called "extraction" is performed. NIST researchers developed software to process the Bell test data into a shorter string of bits that are nearly uniform; that is, with 0s and 1s equally likely. The full process requires the input of two independent strings of random bits to select measurement settings for the Bell tests and to "seed" the software to help extract the randomness from the original data. NIST researchers used a conventional random number generator to generate these input strings. From 55,110,210 trials of the Bell test, each of which produces two bits, researchers extracted 1,024 bits certified to be uniform to within one trillionth of 1 percent. "A perfect coin toss would be uniform, and we made 1,024 bits almost perfectly uniform, each extremely close to equally likely to be 0 or 1," Bierhorst said. Other researchers have previously used Bell tests to generate random numbers, but the NIST method is the first to use a loophole-free Bell test and to process the resulting data through extraction. Extractors and seeds are already used in classical random number generators; in fact, random seeds are essential in computer security and can be used as encryption keys. In the new NIST method, the final numbers are certified to be random even if the measurement settings and seed are publicly known; the only requirement is that the Bell test experiment be physically isolated from customers and hackers. "The idea is you get something better out (private randomness) than what you put in (public randomness)," Bierhorst said. Story Source: Materials provided by National Institute of Standards and Technology (NIST)Note: Content may be edited for style and length. Journal Reference: 1. Peter Bierhorst, Emanuel Knill, Scott Glancy, Yanbao Zhang, Alan Mink, Stephen Jordan, Andrea Rommal, Yi-Kai Liu, Bradley Christensen, Sae Woo Nam, Martin J. Stevens, Lynden K. Shalm. Experimentally Generated Randomness Certified by the Impossibility of Superluminal SignalsNature, 2018 DOI: 10.1038/s41586-018-0019-0 Read me... ## Celebrating π day at the office Celebrating π day at the office thanks to the nice people of people.io Read me... ## Physicists are planning to build lasers so powerful they could rip apart empty space Physicists are planning to build lasers so powerful they could rip apart empty space | Science | AAAS Physicists are planning to build lasers so powerful they could rip apart empty space A laser in Shanghai, China, has set power records yet fits on tabletops. KAN ZHAN Inside a cramped laboratory in Shanghai, China, physicist Ruxin Li and colleagues are breaking records with the most powerful pulses of light the world has ever seen. At the heart of their laser, called the Shanghai Superintense Ultrafast Laser Facility (SULF), is a single cylinder of titanium-doped sapphire about the width of a Frisbee. After kindling light in the crystal and shunting it through a system of lenses and mirrors, the SULF distills it into pulses of mind-boggling power. In 2016, it achieved an unprecedented 5.3 million billion watts, or petawatts (PW). The lights in Shanghai do not dim each time the laser fires, however. Although the pulses are extraordinarily powerful, they are also infinitesimally brief, lasting less than a trillionth of a second. The researchers are now upgrading their laser and hope to beat their own record by the end of this year with a 10-PW shot, which would pack more than 1000 times the power of all the world's electrical grids combined. The group's ambitions don't end there. This year, Li and colleagues intend to start building a 100-PW laser known as the Station of Extreme Light (SEL). By 2023, it could be flinging pulses into a chamber 20 meters underground, subjecting targets to extremes of temperature and pressure not normally found on Earth, a boon to astrophysicists and materials scientists alike. The laser could also power demonstrations of a new way to accelerate particles for use in medicine and high-energy physics. But most alluring, Li says, would be showing that light could tear electrons and their antimatter counterparts, positrons, from empty space—a phenomenon known as "breaking the vacuum." It would be a striking illustration that matter and energy are interchangeable, as Albert Einstein's famous E=mc2 equation states. Although nuclear weapons attest to the conversion of matter into immense amounts of heat and light, doing the reverse is not so easy. But Li says the SEL is up to the task. "That would be very exciting," he says. "It would mean you could generate something from nothing." The Chinese group is "definitely leading the way" to 100 PW, says Philip Bucksbaum, an atomic physicist at Stanford University in Palo Alto, California. But there is plenty of competition. In the next few years, 10-PW devices should switch on in Romania and the Czech Republic as part of Europe's Extreme Light Infrastructure, although the project recently put off its goal of building a 100-PW-scale device. Physicists in Russia have drawn up a design for a 180-PW laser known as the Exawatt Center for Extreme Light Studies (XCELS), while Japanese researchers have put forward proposals for a 30-PW device. Largely missing from the fray are U.S. scientists, who have fallen behind in the race to high powers, according to a study published last month by a National Academies of Sciences, Engineering, and Medicine group that was chaired by Bucksbaum. The study calls on the Department of Energy to plan for at least one high-power laser facility, and that gives hope to researchers at the University of Rochester in New York, who are developing plans for a 75-PW laser, the Optical Parametric Amplifier Line (OPAL). It would take advantage of beamlines at OMEGA-EP, one of the country's most powerful lasers. "The [Academies] report is encouraging," says Jonathan Zuegel, who heads the OPAL. Invented in 1960, lasers use an external "pump," such as a flash lamp, to excite electrons within the atoms of a lasing material—usually a gas, crystal, or semiconductor. When one of these excited electrons falls back to its original state it emits a photon, which in turn stimulates another electron to emit a photon, and so on. Unlike the spreading beams of a flashlight, the photons in a laser emerge in a tightly packed stream at specific wavelengths. Because power equals energy divided by time, there are basically two ways to maximize it: Either boost the energy of your laser, or shorten the duration of its pulses. In the 1970s, researchers at Lawrence Livermore National Laboratory (LLNL) in California focused on the former, boosting laser energy by routing beams through additional lasing crystals made of glass doped with neodymium. Beams above a certain intensity, however, can damage the amplifiers. To avoid this, LLNL had to make the amplifiers ever larger, many tens of centimeters in diameter. But in 1983, Gerard Mourou, now at the École Polytechnique near Paris, and his colleagues made a breakthrough. He realized that a short laser pulse could be stretched in time—thereby making it less intense—by a diffraction grating that spreads the pulse into its component colors. After being safely amplified to higher energies, the light could be recompressed with a second grating. The end result: a more powerful pulse and an intact amplifier. Read me... ## Now reading: "Creation” Now reading: "Creation: The Origin of Life" by Adam Rutherford Read me... ## Beer; and the Mpemba Effect No, sadly this is not a post about observing the Mpemba effect on beer. Instead is about me reading about new studies about the Mpemba effect - i.e. the effect that hot water freezes faster than lukewarm or cool water - while enjoying a cold beer. Cal me a geek! Read me... ## Geek Reading Some time for a bit of geek reading. Read me... ## LIGO Architects Win Nobel Prize in Physics Article from Natalie Wolchover - Quanta Magazine To find the smallest of the small, it pays to dream big. The American physicists Rainer Weiss, Kip Thorne and Barry Barish shared the 2017 Nobel Prize in Physics today for their leading roles in the https://www.quantamagazine.org/gravitational-waves-discovered-at-long-last-20160211/,” tiny ripples in space-time set in motion by faraway cataclysms such as the collisions of black holes. The existence of gravitational waves was predicted a century ago by Albert Einstein, who assumed they would be far too weak to ever detect. But Weiss, Thorne, Barish and the late Scottish physicist Ronald Drever spent decades building a hypersensitive experiment that did just that, recording contractions and expansions in the fabric of space-time less than one-thousandth the width of an atomic nucleus. “It’s really wonderful,” Weiss said after learning of the prize this morning. “But I view this more as a thing that is recognizing the work of about 1,000 people, a dedicated effort that’s been going on for, I hate to tell you, as long as 40 years.” In the 1960s, Thorne, a black hole expert at the California Institute of Technology who is now 77, came to believe that collisions between the invisible monsters he studied should be detectable as gravitational waves. Meanwhile, across the country at the Massachusetts Institute of Technology’s https://www.quantamagazine.org/rainer-weiss-remembering-the-little-room-in-the-plywood-palace-20170615/,” Weiss, now 85, came up with the concept for how to detect them. They, along with Drever, founded in 1984 the project that became the Laser Interferometer Gravitational-Wave Observatory (LIGO). More than three decades later, in September 2015, LIGO’s two giant detectors recorded gravitational waves for the first time. “This was a high-risk, very-high-potential-payoff enterprise,” Thorne told Quanta last year. After LIGO’s breakthrough success, he and Weiss were seen as shoo-ins to win a physics Nobel. The committee chose to give half of the award to Weiss and split the other half between Thorne and Barish. (Drever, who died in March, was ineligible as the prize is not awarded posthumously, and the gravitational-wave discovery did not make the deadline for consideration last year.) Barish’s recognition by the Nobel committee was harder to predict. He “was the organizational genius who made this thing go,” Thorne told Quanta. Barish, a Caltech particle physicist who is now 81, replaced the talented but discordant “troika” of Drever, Thorne and Weiss as leader of LIGO in 1994. Barish established the LIGO Scientific Collaboration, which now has more than 1,000 members, and orchestrated the construction of LIGO’s detectors in Louisiana and Washington state. Left to right: Kip Thorne, Rainer Weiss and Barry Barish. From left to right: Courtesy of the Caltech Alumni Association; Bryce Vickmark; R. Hahn Weiss, Thorne and Barish — all now professors emeritus — and their LIGO collaborators have kick-started a new era of astrophysics by tuning in to these tremors in space-time geometry. As they radiate past Earth, gusts of gravitational waves alternately stretch and squeeze the four-kilometer-long arms of LIGO’s detectors by a fraction of an atom’s width. With princess-and-pea sensitivity, laser beams bouncing along both arms of the L-shape detectors overlap to reveal fleeting differences in the arms’ lengths. By studying the form of a gravitational-wave signal, scientists can extract details about the faraway, long-ago cataclysm that produced it. Just last week, for example, LIGO announced its fourth and latest gravitational-wave detection. Its two detectors, along with a new detector in Europe called Virgo, registered the signal from two enormous black holes 1.8 billion light-years away. After circling each other for eons, the pair finally collided, radiating three suns’ worth of energy into space in the form of telltale gravitational waves. These detections are “opening a new window to the universe,” said Olga Botner, an astrophysicist at Uppsala University in Sweden, during the announcement of the prize this morning. Already, the incoming gravitational-wave signals are https://www.quantamagazine.org/colliding-black-holes-tell-new-story-of-stars-20160906/, and initiating a new era of astronomy. Future gravitational-wave observatories with even greater sensitivity could test ideas about quantum gravity and, maybe, detect signals from the Big Bang itself. “That would be one of the most fascinating things man could do, because it would tell you very much how the universe started,” said Weiss shortly after the announcement. “Gravitational waves, because they are so imperturbable — they go through everything — they will tell you the most information you can get about the earliest instants that go on in the universe.” This article was updated on October 3, 2017, with additional details from the Nobel Prize announcement. It was also corrected to reflect that Rainer Weiss is now 85. Read me... ## A new "Mathematician's Apology" - Reblog In the two and a half years (or so) since I left academia for industry, I’ve worked with a number of math majors and math PhDs outside of academia and talked to a number of current grad students who were considering going into industry. As a result, my perspective on the role of the math research […] Read me... ## Bessel series for a constant Fourier series express functions as a sum of sines and cosines of different frequencies. Bessel series are analogous, expressing functions as a sum of Bessel functions of different orders. Fourier series arise naturally when working in rectangular coordinates. Bessel series arise naturally when working in polar coordinates. The Fourier series for a constant is trivial. You can think of a constant as a cosine with frequency zero. The Bessel series for a constant is not as simple, but more interesting. Here we have:$latex 1=J_0(x)+2J_2(x)+2J_4(x)+2J_g(x)\cdots$Since$latex J_{-n} = (-1)^n J_n(x)$we can write the series above as the following infinite series:$latex 1 = \sum_{n=-\infty}^{\infty} J_{2n}(x)$Cool, right? Read me... ## "Essential Matlab and Octave" in the CERN Document Server I got pinged this screenshot from a friend that saw "Essential MATLAB and Octave" being included in the CERN Document Server! Chuffed! Read me... ## 3 Things Everyone Should Know About Physics This is an exceptionally good answer to the question: "What do physicists wish the average person knew about physics?" The answer was written by Inna Vishik, Assistant Professor of Physics at the University of California, Davis. • Physics makes predictive models about the natural world based on empirical observations (experiments), mathematics, and numerical simulations. These models are called ‘theories’, but this does not mean they are speculative; physics theories explain past behavior and predict future behavior. When a previously-validated theory fails to explain the behavior in a new physical system, it doesn’t mean the theory is suddenly ‘wrong’ altogether, it means that it is inapplicable in a certain regime. It is very exciting for physicists when these exceptions are found, and it is in these holes in our models that we propel our understanding of the physical world forward. • The domain of physics is vast. Some physicists study the existing universe around us. Some study the smallest constituent particles and forces of matter in this universe. Some manipulate clusters of atoms, and some manipulate light. Some study crystalline solids and the myriad properties they can have when quadrillions of atoms and electrons are arranged in slightly different ways. Others study biological systems. This is not a full list of the many subfields in physics, but what they all have in common is they combine classical (including continuum) mechanics, quantum mechanics, statistical mechanics, general relativity, and electricity and magnetism in various configurations to explain the physical and engineered world around us. • Research in physics and other fundamental sciences play three crucial roles in an advanced society; they cement our cultural legacy by exploring one aspect of the human condition (the universe we occupy), similar to the role of the arts; they educate a portion of the work force in solving difficult, open ended problems beyond the limits of prior human innovation; they provide the seeds for future technological developments, which is often realized decades in the future in an unpredictable manner (i.e. not amenable to quarterly earnings reports). At the time of their inception, electromagnetic waves (late 19th century), quantum mechanics (early 20th century) and lasers (mid 20th century) were viewed even by their progenitors as esoteric curiosities; now they permeate our life, technology, and medicine so deeply that no one would question their practical importance. In the modern physics research era, there are newer ideas that might have an equally important impact 50 years from now, but they will never be realized without continued investment in the public good known as fundamental science. ## Zz. --Dr J Rogel-Salazar Read me... ## A new house for the Design Museum in London If you had the opportunity to walk near Holland Park, you probably are familiar with the location where the Commonwealth Institute used to be: a Grade II listed building dating back to the 1960s. The building was designed by Robert Matthew/Sir Robert Matthew, Johnson-Marshall and Partners, architects, and engineered by AJ & JD Harris, of Harris & Sutherland. The building is the new house for the Design Museum. The museum was founded in 1989, originally located by the River Thames near Tower Bridge in London, and recently relocated to Kensington opening its doors on November 24th, 2016. The museum covers product, industrial, graphic, fashion and architectural design. The new location also houses the Swarovski Foundation Centre for Learning, 202-seat Bakala Auditorium and a dedicated gallery to display its permanent collection, accessible free of charge. I recently visited the museum and had the opportunity to attend the Beazley Designs of the Year exhibition currently being shown. The exhibition showcases designs produced over the previous twelve months worldwide.The entries are nominated by a number of internationally respected design experts a, falling into the seven categories of Architecture, Transport, Graphics, Interactive, Product, Furniture and Fashion. Since 2015 there have been six categories: architecture, fashion, graphics, digital, product and transport. Beazley Insurance came on board as exhibition sponsor in 2016. I was very pleased to see at least two entries from Mexico. One of them is the work of the mexican Alejandro Magallanes for the Almadía publishing house, a small but innovative publisher based in Oaxaca, Mexico. I highly recommend reading the post in Yorokobu entitled "Las portadas exquisitas de Alejandro Magallanes". Name: Almadía book covers design Designers: Alejandro Magallanes Paragraph description: The front covers for the Almadia book series was conceived when Magallanes looked into the archives and origins of the Almadia publishing house. Creating a bold design, the covers add an element of craftsmanship whilst providing an object that the reader would like to behold. The other entry from Mexico was Yakampot, a fashion brand that aims to become an international name while embracing the cultural heritage of the country's womenswear. Also notable are the entries from Jonathan Barnbrook for the design of David Bowie's last album "Blackstar", as well as the Space Cup that enables astronauts to drink from a cup rather than a straw, developed on the International Space Station. The cup was a result of addressing the microgravity effects faced by fluids while at zero-gravity. The project "Capillary Effects of Drinking in the Microgravity Environment" (Capillary Beverage) studied the process of drinking from specially designed Space Cups that use fluid dynamics to mimic the effect of gravity. Designers: Jonathan Barnbrook One line description: The album cover uses the Unicode Blackstar symbol creating a simplicity to the design allowing the music to be the focus and the creation of an identity that is easy to identify and share. Paragraph description: The album cover uses the Unicode Blackstar symbol creating a simplicity to the design allowing the music to be the focus and the creation of an identity that is easy to identify and share. Designed using open source elements, the artwork for the album became open sourced itself following Bowie’s death enabling fans to engage, interact and use it. Name: Space Cup Designers: Mark Weislogel: Innovator (IRPI LLC/Portland State University) Andrew Wollman: Designer (IRPI LLC) John Graf: Co-Investigator (NASA Johnson Space Center) Donald Pettit: NASA Astronaut Innovator (NASA Johnson Space Center) Ryan Jenson: Sponsor (IRPI LLC) One line description: Using capillary forces to replace the role of gravity, the Space Cup enables astronauts to drink from a cup rather than a straw and was developed on the International Space Station. Paragraph description: The Space Cup was designed and developed using scientific results of experiments conducted aboard the International Space Station. The cup is designed to exploit passive capillary forces to replace the role of gravity in an earth-like drinking experience, but in the low-gravity environment of space. Sealed drink bags are normally sipped through a straw to avoid spilling in space. The Space Cup however uses surface tension, fluid wetting properties, and a unique shape to drive the liquid toward the astronaut’s mouth while drinking. Read me... ## Comet 45P Returns Comet 45P Returns An old comet has returned to the inner Solar System. Not only is Comet 45P/Honda–Mrkos–Pajdušáková physically ancient, it was first discovered 13 orbits ago in 1948. Comet 45P spends most of its time out near the orbit of Jupiter and last neared the Sun in 2011. Over the past few months, however, Comet 45P's new sunward plummet has brightened it considerably. Two days ago, the comet passed the closest part of its orbit to the Sun. The comet is currently visible with binoculars over the western horizon just after sunset, not far from the much brighter planet Venus. Pictured, Comet 45P was captured last week sporting a long ion tail with impressive structure. Comet 45P will pass relatively close to the Earth early next month. Read me... ## Shell Game in the LMC Shell Game in the LMC An alluring sight in southern skies, the Large Magellanic Cloud (LMC) is seen here through narrowband filters. The filters are designed to transmit only light emitted by ionized sulfur, hydrogen, and oxygen atoms. Ionized by energetic starlight, the atoms emit their characteristic light as electrons are recaptured and the atom transitions to a lower energy state. As a result, this false color image of the LMC seems covered with shell-shaped clouds of ionized gas surrounding massive, young stars. Sculpted by the strong stellar winds and ultraviolet radiation, the glowing clouds, dominated by emission from hydrogen, are known as H II (ionized hydrogen) regions. Itself composed of many overlapping shells, the Tarantula Nebula is the large star forming region at top center. A satellite of o ur Milky Way Galaxy, the LMC is about 15,000 light-years across and lies a mere 180,000 light-years away in the constellation Dorado. Read me... ## Supermoon over Spanish Castle No, this castle was not built with the Moon attached. To create the spectacular juxtaposition, careful planning and a bit of good weather was needed. Pictured, the last supermoon of 2016 was captured last week rising directly beyond one of the towers of Bellver Castle in Palma de Mallorca on the Balearic Islands of Spain. The supermoon was the last full moon of 2016 and known to some as the Oak MoonBellver Castle was built in the early 1300s and has served as a home -- but occasional as a prison -- to numerous kings and queens. The Moon was built about 4.5 billion years ago, possibly resulting from a great collision with a Mars-sized celestial body and Earth. The next supermoon, defined as when the moonappears slightly larger and brighter than usual, will occur on 2017 December 3 and be visible not only behind castles but all over the Earth. via Space http://ift.tt/2hA2eqg Read me... ## Nobel Prize in Physics 2016: Exotic States of Matter Yesterday the 2016 Nobel Prize in Physics was announced. I immediately got a few tweets asking for more information about what these "exotic" states of matter were and explain more about them... Well in short the prize was awarded for the theoretical discoveries that help scientists understand unusual properties of materials, such as superconductivity and superfluidity, that arise at low temperatures. The prize was awarded jointly to David J. Thouless of the University of Washington in Seattle, F. Duncan M. Haldane of Princeton University in New Jersey, and J. Michael Kosterlitz of Brown University in Rhode Island. The citation from the Swedish Academy reads: "for theoretical discoveries of topological phase transitions and topological phases of matter." "Topo...what?" - I hear you cry... well let us start at the beginning... Thouless, Haldane and Kosterliz work in a field of physics known as Condensed Matter Physics and it is interested in the physical properties of "condensed" materials such as solids and liquids. You may not know it, but results from research in condensed matter physics have made it possible for you to save a lot of data in your computer's hard drive: the discovery of giant magnetoresistance has made it possible. The discoveries that the Nobel Committee are highlighting with the prize provide a better understanding of phases of matter such as superconductors, superfluids and thin magnetic films. The discoveries are now guiding the quest for next generation materials for electronics, quantum computing and more. They have developed mathematical models to describe the topological properties of materials in relation to other phenomena such as superconductivity, superfluidity and other peculiar magnetic properties. Once again that word: "topology"... So, we know that all matter is formed by atoms. Nonetheless matter can have different properties and appear in different forms, such as solid, liquid, superfluid, magnet, etc. These various forms of matter are often called states of matter or phases. According to condensed matter physics , the different properties of materials originate from the different ways in which the atoms are organised in the materials. Those different organizations of the atoms (or other particles) are formally called the orders in the materials. Topological order is a type of order in zero-temperature phase of matter (also known as quantum matter). In general, topology is the study of geometrical properties and spatial relations unaffected by the continuous change of shape or size of figures. In our case, we are talking about properties of matter that remain unchanged when the object is flattened or expanded. Although, research originally focused on topological properties in 1-D and 2-D materials, researchers have discovered them in 3-D materials as well. These results are particularly important as they enable us to understanding "exotic" phenomena such as superconductivity, the property of matter that lets electrons travel through materials with zero resistance, and superfluidity, which lets fluids flow with zero loss of kinetic energy. Currently one of the most researched topics in the area is the study of topological insulators, superconductors and metals. Here is a report from Physics Today about the Nobel Prize announcement: Thouless, Haldane, and Kosterlitz share 2016 Nobel Prize in Physics David Thouless, Duncan Haldane, and Michael Kosterlitz are to be awarded the 2016 Nobel Prize in Physics for their work on topological phases and phase transitions, the Royal Swedish Academy of Sciences announced on Tuesday. Thouless, of the University of Washington in Seattle, will receive half the 8 million Swedish krona (roughly$925 000) prize; Haldane, of Princeton University, and Kosterlitz, of Brown University, will split the other half.

This year’s laureates used the mathematical branch of topology to make revolutionary contributions to their field of condensed-matter physics. In 1972 Thouless and Kosterlitz identified a phase transition that opened up two-dimensional systems as a playground for observing superconductivity, superfluidity, and other exotic phenomena. A decade later Haldane showed that topology is important in considering the properties of 1D chains of magnetic atoms. Then in the 1980s Thouless and Haldane demonstrated that the unusual behavior exhibited in the quantum Hall effect can emerge without a magnetic field.

From early on it was clear that the laureates’ work would have important implications for condensed-matter theory. Today experimenters are studying 2D superconductors and topological insulators, which are insulating in the bulk yet channel spin-polarized currents on their surfaces without resistance (see Physics Today, January 2010, page 33). The research could lead to improved electronics, robust qubits for quantum computers, and even an improved understanding of the standard model of particle physics.

Vortices and the KT transition

When Thouless and Kosterlitz first collaborated in the early 1970s, the conventional wisdom was that thermal fluctuations in 2D materials precluded the emergence of ordered phases such as superconductivity. The researchers, then at the University of Birmingham in England, dismantled that argument by investigating the interactions within a 2D lattice.

Thouless and Kosterlitz considered an idealized array of spins that is cooled to nearly absolute zero. At first the system lacks enough thermal energy to create defects, which in the model take the form of localized swirling vortices. Raising the temperature spurs the development of tightly bound pairs of oppositely rotating vortices. The coherence of the entire system depends logarithmically on the separation between vortices. As the temperature rises further, more vortex pairs pop up, and the separation between partners grows.

The two scientists’ major insight came when they realized they could model the clockwise and counterclockwise vortices as positive and negative electric charges. The more pairs that form, the more interactions are disturbed by narrowly spaced vortices sitting between widely spaced ones. “Eventually, the whole thing will fly apart and you'll get spontaneous ‘ionization,’ ” Thouless told Physics Today in 2006.

That analog to ionization, in which the coherence suddenly falls off in an exponential rather than logarithmic dependence with distance, is known as the Kosterlitz–Thouless (KT) transition. (The late Russian physicist Vadim Berezinskii made a similar observation in 1970, which led some researchers to add a “B” to the transition name, but the Nobel committee notes that Berezinskii did not theorize the existence of the transition at finite temperature.)

Unlike some other phase transitions, such as the onset of ferromagnetism, no symmetry is broken. The sudden shift between order and disorder also demonstrates that superconductivity could indeed subsist in the 2D realm at temperatures below that of the KT transition. Experimenters observed the KT transition in superfluid helium-4 in 1978 and in superconducting thin films in 1981. More recently, the transition was reproduced in a flattened cloud of ultracold rubidium atoms (see Physics Today, August 2006, page 17).

A topological answer for the quantum Hall effect

Thouless then turned his attention to the quantum foundations of conductors and insulators. In 1980 German physicist Klaus von Klitzing had applied a strong magnetic field to a thin conducting film sandwiched between semiconductors. The electrons traveling within the film separated into well-organized opposing lanes of traffic along the edges (see Physics Today, June 1981, page 17). Von Klitzing had discovered the quantum Hall effect, for which he would earn the Nobel five years later.

Crucially, von Klitzing found that adjusting the strength of the magnetic field changed the conductance of his thin film only in fixed steps; the conductance was always an integer multiple of a fixed value, e2/h. That discovery proved the key for Thouless to relate the quantum Hall effect to topology, which is also based on integer steps—objects are often distinguished from each other topologically by the number of holes or nodes they possess, which is always an integer. In 1983 Thouless proposed that the electrons in von Klitzing’s experiment had formed a topological quantum fluid; the electrons’ collective behavior in that fluid, as measured by conductance, must vary in steps.

Not only did Thouless’s work explain the integer nature of the quantum Hall effect, but it also pointed the way to reproducing the phenomenon’s exotic behavior under less extreme conditions. In 1988 Haldane proposed a means for electrons to form a topological quantum fluid in the absence of a magnetic field. Twenty-five years later, researchers reported such behavior in chromium-doped (Bi,Sb)2Te3, the first observation of what is known as the quantum anomalous Hall effect.

Exploring topological materials

Around 2005, physicists began exploring the possibility of realizing topological insulators, a large family of new topological phases of matter that would exhibit the best of multiple worlds: They would robustly conduct electricity on their edges or surfaces without a magnetic field and as a bonus would divide electron traffic into lanes determined by spin. Since then experimenters have identified topological insulators in two and three dimensions, which may lead to improved electronics. Other physicists have created topological insulators that conduct sound or light, rather than electrons, on their surfaces (see Physics Today, May 2014, page 68).

Haldane’s work in the 1980s on the fractional quantum Hall effect was among the theoretical building blocks for proposals to use topologically protected excitations to build a fault-tolerant quantum computer (see Physics Today, October 2005, page 21). And his 1982 paper on magnetic chains serves as the foundation for efforts to create topologically protected excitations that behave like Majorana fermions, which are their own antiparticle. The work could lead to robust qubits for preserving the coherence of quantum information and perhaps provide particle physicists with clues as to the properties of fundamental Majorana fermions, which may or may not exist in nature.

—Andrew Grant

## Rosetta's Farewell

Rosetta's Farewell
After closely following comet 67P/Churyumov-Gerasimenko for 786 days as it rounded the Sun, the Rosetta spacecraft's controlled impact with the comet's surface was confirmed by the loss of signal from the spacecraft on September 30, 2016. One the images taken during its final descent, this high resolution view looks across the comet's stark landscape. The scene spans just over 600 meters (2,000 feet), captured when Rosetta was about 16 kilometers from the comet's surface. Rosetta's descent to the comet brought to an end the operational phase of an inspirational mission of space exploration. Rosetta deployed a lander to the surface of one of the Solar System's most primordial worlds and witnessed first hand how a comet changes when subject to the increasing intensity of the Sun's radiation. The decision to end the mission on the surface is a result of the comet's orbit now taking it to the dim reaches beyond Jupiter where there would be a lack of power to operate the spacecraft. Mission operators also faced an approaching period where the Sun would be close to line-of-sight between Earth and Rosetta, making radio communications increasingly difficult.

## Visiting Hursley House and The IBM Galileo Centre

Today I was in Hursely and I had the opportunity of spending the day at Hursely House and the IBM Galileo Centre. Very nice grounds and a very inspiring place. Judge for yourselves!

Happy π day!

## Quantum algorithms for topological and geometric analysis of data

Story Source:

The above post is reprinted from materials provided by Massachusetts Institute of Technology. The original item was written by David L. Chandler. Note: Materials may be edited for content and length.

From gene mapping to space exploration, humanity continues to generate ever-larger sets of data -- far more information than people can actually process, manage, or understand.

Machine learning systems can help researchers deal with this ever-growing flood of information. Some of the most powerful of these analytical tools are based on a strange branch of geometry called topology, which deals with properties that stay the same even when something is bent and stretched every which way.

Such topological systems are especially useful for analyzing the connections in complex networks, such as the internal wiring of the brain, the U.S. power grid, or the global interconnections of the Internet. But even with the most powerful modern supercomputers, such problems remain daunting and impractical to solve. Now, a new approach that would use quantum computers to streamline these problems has been developed by researchers at MIT, the University of Waterloo, and the University of Southern California.

The team describes their theoretical proposal this week in the journal Nature Communications. Seth Lloyd, the paper's lead author and the Nam P. Suh Professor of Mechanical Engineering, explains that algebraic topology is key to the new method. This approach, he says, helps to reduce the impact of the inevitable distortions that arise every time someone collects data about the real world.

In a topological description, basic features of the data (How many holes does it have? How are the different parts connected?) are considered the same no matter how much they are stretched, compressed, or distorted. Lloyd explains that it is often these fundamental topological attributes "that are important in trying to reconstruct the underlying patterns in the real world that the data are supposed to represent."

It doesn't matter what kind of dataset is being analyzed, he says. The topological approach to looking for connections and holes "works whether it's an actual physical hole, or the data represents a logical argument and there's a hole in the argument. This will find both kinds of holes."

Using conventional computers, that approach is too demanding for all but the simplest situations. Topological analysis "represents a crucial way of getting at the significant features of the data, but it's computationally very expensive," Lloyd says. "This is where quantum mechanics kicks in." The new quantum-based approach, he says, could exponentially speed up such calculations.

Lloyd offers an example to illustrate that potential speedup: If you have a dataset with 300 points, a conventional approach to analyzing all the topological features in that system would require "a computer the size of the universe," he says. That is, it would take 2300 (two to the 300th power) processing units -- approximately the number of all the particles in the universe. In other words, the problem is simply not solvable in that way.

"That's where our algorithm kicks in," he says. Solving the same problem with the new system, using a quantum computer, would require just 300 quantum bits -- and a device this size may be achieved in the next few years, according to Lloyd.

"Our algorithm shows that you don't need a big quantum computer to kick some serious topological butt," he says.

There are many important kinds of huge datasets where the quantum-topological approach could be useful, Lloyd says, for example understanding interconnections in the brain. "By applying topological analysis to datasets gleaned by electroencephalography or functional MRI, you can reveal the complex connectivity and topology of the sequences of firing neurons that underlie our thought processes," he says.

The same approach could be used for analyzing many other kinds of information. "You could apply it to the world's economy, or to social networks, or almost any system that involves long-range transport of goods or information," Lloyd says. But the limits of classical computation have prevented such approaches from being applied before.

While this work is theoretical, "experimentalists have already contacted us about trying prototypes," he says. "You could find the topology of simple structures on a very simple quantum computer. People are trying proof-of-concept experiments."

The team also included Silvano Garnerone of the University of Waterloo in Ontario, Canada, and Paolo Zanardi of the Center for Quantum Information Science and Technology at the University of Southern California.

## Artificial Intelligence - Debunking Myths

HAL 9000 in the film 2001.

It is a good read and it you have a few minutes to spare, do give it a go.

1. AI's makes machines that can think.
2. AI will not be bound by human ethics.
3. AI will get out of control
4. Breakthroughs in AI will all happen in sudden jumps.

It is true that there are a number of effort to try to replicate (and therefore understand) human thought. Some examples include the Blue Brain project in the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland. However, this does not imply that they will get immediately a machine such as HAL or C3-PO.

This is because the brain is fat more complex than the current efforts are able to simulate. As a matter of fact, even simpler brains are significantly more complex for simulation. This does not mean that we should not try to understand and learn how brains work.

Part of the problem is that it is difficult to even define what we mean by “thought”— the so called hard problem. So finding a solution to the strong AI problem is not going to be here soon, but we should definitely try.

So, once that myth is out of the way, the idea that a Terminator-like robot is around the corner is put into perspective. Sure, there are attempts at getting some self-driving cars and such but we are not quite there yet. All in all, it is true that a number of technological advances can be used for good or bad causes, and that is surely something that we all should bear in mind.

## Einstein's Amazing Theory of Gravity

Earlier this week I attended a talk by Sir Roger Penrose FRS in celebration of the 100th anniversary of the publication of Einstein´s General Theory of Relativity. The talk was entitled Einstein’s Amazing Theory of Gravity and it was sponsored by the London Mathematical Society (of which I am a proud member) and held at the Science Museum as part of the November Lates events. It also coincided with the 150th anniversary of the LMS!

Not only was the LMS and the Science Museum commemorating the centenary of the birth of Einstein’s Theory of General Relativity but other outlets were too. It may be difficult to put an actual date to Einstein's work, but we know that on November 25th, 1915 Einstein presented the “final” form of his theory to the Prussian Academy of Sciences. You can find a full translation of the paper “The Field Equations of Gravitation” here. It is interesting to note that he refers to a couple of earlier papers in that work, but the one we are referring to presents the theory in full.

During his talk, Penrose indeed talked about Relativity and I would have preferred that he concentrated on the theory per se at a more introductory level, after all it was part of a public talk in the Science Museum. He talked about black holes and did not shy talking about conformal geometries for example (bravo!). He finished his talk by presenting some of his own work regarding eons and cyclical cosmology. You can get a flavour of what he talked about in this recording of a lecture he gave in 2010.

## Life lessons from differential equations

Ten life lessons from differential equations:

1. Some problems simply have no solution.
2. Some problems have no simple solution.
3. Some problems have many solutions.
4. Determining that a solution exists may be half the work of finding it.
5. Solutions that work well locally may blow up when extended too far.
6. Boundary conditions are the hard part.
7. Something that starts out as a good solution may become a very bad solution.
8. You can fool yourself by constructing a solution where one doesn’t exist.
9. Expand your possibilities to find a solution, then reduce them to see how good the solution is.
10. You can sometimes do what sounds impossible by reframing your problem.

## n sweets in a bag, some are orange...

The other day in the news there was a note about a particular question in one of the national curriculum exams... I thought it was a bit of an odd thing for a maths question to feature in the news and so I thought of having a look a the question. Here it is:

There are $latex n$ sweets in a bag.

6 of the sweets are orange.

The rest of the sweets are yellow.

Hannah takes at random a sweet form the bag. She eats the sweet.

Hannah then takes at random another sweet from the bag. She eats the sweet.

The probability that Hanna eats two orange sweets is $latex \frac{1}{3}.$

a) Show that $latex n^2-n-90=0$

It sounds like an odd question, but after giving it a bit of thought it is actually quite straightforward; and I am glad they ask something that makes you think, rather than something that is purely a mechanical calculation.

So, let's take a look: Hannah is taking sweets from the bag at random and without replacement (she eats the sweets after all). So we are told that there are 6 orange sweets, so at the beginning of the sweet-eating binge, the probability of picking an orange sweet is:

$latex \displaystyle P(\text{1 orange sweet}) = \frac{6}{n}$.

Hannah eats the sweet, remember... so in the second go at the sweets, the probability of an orange sweet is now:

$latex \displaystyle P(\text{2nd orange sweet}) = \frac{5}{n-1}$.

Now, they tell us that the probability of eating two orange sweets is $latex \frac{1}{3}$, so we have that:

$latex \displaystyle \left( \frac{6}{n} \right)\left( \frac{5}{n-1} \right)=\frac{1}{3}$,

$latex \displaystyle \frac{30}{n^2-n} =\frac{1}{3}$,

$latex \displaystyle n^2-n = 90$,

which is the expression we were looking for. Furthermore, you can then solve this quadratic equation to find that the total number of sweets in the bag is 10.

The only thing we don't know is if the sweets are just orange in colour, or also in flavour! We will have to ask Hannah!

## Shelf Life - The Tiniest Fossils

Really thrilled to continue seeing the American Museum of Natural History series Shelf Life. I blogged about this series earlier on in the year and they have kept to their word with interesting and unique instalments.

In Episode 6 we get to hear about micropaleontology, the study of fossil specimens that are so tiny you cannot see them with the naked eye. The scientist and researchers tell us about foramnifera, unicellular organisms belonging to the kingdom Protista and which go back to about 65 million years. In spite of being unicellular, they make shells! And this is indeed what makes it possible for them to become fossilised.

Interestingly enough these fossils allow us to used them as ways to tell something about ancient climate data. As Roberto Moncada pointed out to me:

According to our expert in the piece, basically every representational graph you’ve ever seen of climate/temperatures from the Earth’s past is derived from analyzing these tiny little creatures.

The Tiniest Fossils are indeed among the most important for climate research!

## 2015 - International Year of Light

2015 has been declared the International Year of Light (IYL 2015) and with me being an optics geek, well, it was difficult to resist to enter a post about it. The IYL 2015 is a global initiative adopted by the United Nations to raise awareness of how optical technologies promote sustainable development and provide solutions to worldwide challenges in areas such as energy, education, communications, health, and sustainability.

There will be a number of event and programs run throughout the year and the aim of many of them is to promote public and political understanding of the central role of light in the modern world while also celebrating noteworthy anniversaries in 2015 - from the first studies of optics 1000 years ago to discoveries in optical communications that power the Internet today.

You can find further information from the well-known OSA here and check out the International Year of Light Blog.

Here are some pictures I took a couple of years ago during CLEO Europe in relationship to the International Year of Light.

## March 2015 Total Solar Eclipse

I know it is a bit late, but with the moving of the blog and all that jazz, I did not have time to post this earlier. This is a video taken by Bob Forrest, a former Specialist Technician at Bayfordbury's Observatory at the University of Hertfordshire. The video is of the Total Solar Eclipse in March 2015.

Enjoy...

## Shelf Life - A great project at the American Museum of Natural History

I am a geek, and proudly so, and as such I have been known to visit exhibitions at the excellent Natural History Museum and the Science Museum in London, the Field Museum in Chicago, or indeed the American Museum of Natural History (AMNH). As a matter of fact, in August I did go to the AMNH and had a great time. I particularly enjoyed the Hayden Planetarium, part of the Rose Center for Earth and Space, with its iconic glass cube encasing the spherical Space Theater.

I am always in awe at the enormous number of items in the collections of these museums, cataloguing human knowledge, from taxonomy and evolution to geology and astrophysics. I was thus really intrigued when Roberto Moncada, from the AMHN sent some information about the most recent project at the museum: Shelf Life.

The AMHN has a collection with over 33 million specimens an artefacts. As it is usually the case, some of these items tell us a story about the state of knowledge at different points in human history and they range from the rare and irreplaceable to the amazing and precious. In the Shelf Life project, the museum keeps at heart its mission to share their collections and educate the public about the work that they do with the help of videos released monthly over the next year. In Episode 1, they take us inside the museum collections: "from centuries-old specimens to entirely new types of specialized collections like frozen tissues and genomic data". Episode 2 they talk to us about the art of the science of classification, taxonomy, and they way in which 33 million (plus) items get organised in the collection of the museum. Go, have a look at their shelves, you will surely find something of interest among those 33 million items!

## Mendeley goodies

I got my Mendeley t-shirt, plus a tote bang and stickers. Thanks @mendeley_com.

## Chris Hadfield event at the Royal Geographical Society

Chris Hadfield is speaking at the Royal Geographical Society in London as part of the Guardian Live events. I managed to get a couple of great seats to hear him speak about his book "You are here". Looking forward to seeing the images he captured while at the ISS.

## Black holes, gravity and film - Depicting gravitational lensing in Interstellar

Listening to the Science Magazine podcast I found out that the black hole depiction (or its effects rather) as shown in the latest film by Christopher Nolan, Interstellar, used the expertise of physicists to create the visualisations. Furthermore, the researchers used the work for the film to write an academic paper!

There are a number of things that are not as sound in the film, for instance the contrast of the efforts to free the ship from the embrace of the Earth's gravitational field, and the whizzing out from a tidal-wave-ridden planet by simply floating away... But, that is not why I wrote this post.... it was to highlight the black hole depiction... so back to the subject. In order to better depict the black hole, the film used the expertise of theoretical astro-physicist Kip Thorne, the Feynman Professor of theoretical Physics at Caltech.

In order to produce the effect of the black hole Thorne, worked together with Double Negative in implementing the equations that would render the visual effect. However, no rendering software was able to do the rendering as they are based on the fact that outside black holes, light rays travel in a straight line. In order to show the gravitational lensing around the black hole a new renderer had to be created. The result were images that took over 100 hours to be  created. The images obtained provided Thorne with unexpected results as they showed that the light that is emitted from the accretion disk around the  black hole would have its light distorted by gravity in such a wat that a halo would apere above and below but also in front of it too. So we just have to wait for the papers to be out and read more about this. In the meantime if you are interested in finding our more about research into black holes take a look at this page.

## Quantum Tunnel Answers: Turning light into matter

Hello everybody, I am very pleased to have received a question from two people I know very well Martin del Campo and Gaby R. They have contacted Quantum Tunnel with the following question:

Breit and Wheeler proposed in 1934 that it should be possible to turn light into matter by smashing together two particles of light to create an electron and a positron – the simplest method of turning light into matter ever predicted. I would like to know if some day could be possible to demonstrate this idea?

Well Gaby and Martin, thanks a lot for the question and I bet this was triggered by the mention of Breit and Wheeler in recent weeks. As you rightly mention, Gregory Breit and John Wheeler proposed the mechanism in a Physical Review A paper entitled "Collision of two light quanta" (PRA 46, 1087; 1934). Although the mechanism was presented about 80 years ago, the difficulty in preparing the gamma rays to be collided has been a great issue to overcome. Back in 1997, researchers of the Stanford Linear Accelerator Center managed to carry out a multi-photon Breit-Wheeler process: They used a stacked way to crate the electrons and positrons using high energy photons that were generated using electrons. So the idea was to a certain extent demonstrated back in 1997, but the production of the electron-positron pair in one single shot is yet to be seen.

The difficulties have now deterred persistent physicists and I am pleased to tell you that efforts continue. In particular, the researchers Pike, Mackenroth, Hill and Rose, from Imperial College London published a paper in Nature Photonics called "A photon-photon collider in a vacuum hohlraum" (Nat. Phot. 8, 434; 2014). By the way a Hohleaum is a cavity whose walls are in radiative equilibrium with the radiant energy within it, the word comes from German and it means "cavity" or "hollow room". In their paper they present the design of a novel photon–photon collider where a gamma-ray beam is fired into a hohlraum. The theoretical simulations in the paper  suggest that this setup can produce about 105 Breit–Wheeler pairs in a single shot. If that is the case, the setup could provide the trail to a first realisation of a photon–photon collider and demonstrate the mechanism that Breit and Wheeler talked about.

## Quantum Tunnel Answers: Fresnel Lens

Hello everyone,

once again we have a question coming to the inbox of the Quantum Tunnel blog. If you are interested in asking a question, please feel free to get in touch using this page. We have once again a question by a very avid reader, let's take a look:

Dear Quantum Tunnel,

Could you please explain how Fresnel lenses work? I am asking after listening to Dr Carlos Macías-Romero talking in one of the Quantum Tunnel podcasts. Thanks a lot.

Pablo

Hello yet again Pablo, thanks a lot for your question. Well, I assume that you are familiar with the idea of a lens and that you may even wear a pair of spectacles or know someone who does and so you know that you can correct, among other things, the focal point and thus read your favourite blog (the Quantum Tunnel site of course!) with trouble.

Well, have you ever had a chance to go and see a lighthouse close enough? But not just the building, the actual place where the light is beamed out to see? If so you may have seen the lenses they use. If not, take a look the image here:

You can see how the lens is made out of various concentric layers of material and the design allows us to construct lenses that otherwise would be way to thick and therefore heavier. A lighthouse requires a light beam that uses a large aperture but a short focal length and a Fresnel lens offers exactly that without the need of a really thick lens. Fresnel lenses are named after the French physicist Augustin-Jean Fresnel.

Another example of Fresnel lenses are flat magnifying glasses such as the one shown below, you can see that they are effectively flat and no need to use one such as those used by Sherlock Holmes...

The design of a Fresnel lens allows it to capture more oblique light from a light source. Remember that a lens works by refracting (bending) the light and the way in which the "layering" in the Fresnel lens helps with the refraction needed. See the diagram below:

A couple of other uses for these lenses are in overhead projectors and the headlights of cars. So next time you attend or give a lecture or drive at night, think of Monsieur Fresnel.

## Quantum Tunnel Answers - Interest in Quantum Physics

This time is not really a question that has arrived to the Quantum Tunnel mailbox, it is rather an observation and some cheers. Let's take a look:

Dear Quantum Tunnel,

I have listened to all the available Quantum Tunnel podcasts in Spanish, the content is great and the news are cool. I am interested in understanding more about quantum theory and in my experience there is no a lot of information at my level that does not make it all sounds like philosophy or even a bad example. In most cases the explanations start up assuming that one does understand the "quantum concepts". With those limitations, I am afraid to admit that I actually fail to see the genius of Einstein. Having said that I refuse to think that after I am unable to understand ideas that are thought in universities. Surely some explanations do not start with "time is relative". If thousands can understand it, so can I.

Pablo Mitlanian

Hello again Pablo, I agree with you that there is a lot of information out there that either assumes too much, or simply exploits the concepts for non-scientific purposes. You are right, I am sure you can understand the intricacies of quantum-mechanical phenomena, but bear in mind the words of Richard Feynman "I think I can safely say that nobody understands quantum mechanics".  I would not expect someone to become a quantum physicist without the appropriate training, in the same way we cannot all perform a heart transplant without studying medicine and practicing. That doesn't mean we can't change careers though!

If you want to learn quantum theory in ten minutes, take a look at the blog post that the Quantum Pontiff blog posted a few years back. Yes, there are ducks and turkeys, but then again they promised to explain in 10 minutes. There are nonetheless a few things that can serve as building blocks to achieve your goal:

1. Learn about classical physics (yes, the courses on mechanics that you probably took in high school, exactly those). A good understanding of this will highlight those non-intuitive results from the quantum world.
2. Understand how to describe the behaviour of particles and of waves (I guess this is part of number 1 above, so just stressing the point!)
3. Make sure you are well versed in the use of probability (yes, I am saying that you need to revise some mathematics!)
4. Be patient!

It all that works, perhaps consider enrolling at your local University to read physics, you never know you make the next discovery in physics. Incidentally, within your revision make sure you understand that relativity theory (general or special) is completely decoupled from quantum theory. As a matter of fact, joining the two is one of the biggest challenges in physics today.

If you want to ask a question to Quantum Tunnel use the form here.

## Quantum Tunnel answers: Solar flares

I am very pleased that the first (of many I hope) questions has arrived to the mailbox of the Quantum Tunnel blog. So here we go:

Dear Quantum Tunnel:

Is it true that there will be a solar storm in December (2014) and there will be three days of darkness? If so, why is this happening?

Yours sincerely,

Pablo Mitlanian

Well, thanks a lot for your question Pablo. Let me first start by clearing the air and respond directly to the question: No, it is not true that there will be a solar storm that will cause three days of darkness. So there you go! I think this is a rumor that has been going around the interwebs for quite some time. Neither NASA nor any other respected scientific institution has made such a claim.

Now, let us address the actual facts related to the question: solar storms do indeed exist and they usually refer to sudden release of energy from the surface of the Sun, we are talking about $latex 6times 10^{25}$ Joules. To put this in perspective, the impact in Chicxulub (Mexico) that caused the mass extinction of the dinosaurs is around $latex 1times 10^8$ Joules. Solar flares are sometimes followed by the ejection of plasma from the upper atmosphere of the Sun (called solar wind) and accompanying magnetic fields. The particles that make up the solar wind (electrons, ions and atoms) reach the Earth one or two days after the event. Incidentally, the charged particles hitting the magnetosphere are the reason for beautiful auroras!

As you can imagine, solar flares have a definite impact on space weather locally, and thus on the Earth too. The particles from the solar wind can impact with the Earths magnetosphere and present some hazard to spacecraft and satellites and in some cases affect the terrestrial electric power grids. One of the most powerful solar flares observed was recorded in 1859 by Richard Carrington and, independently, Richard Hodgson and the auroras could be seen even in Cuba and Hawaii!

The Sun's magnetic activity has been observed to follow a periodic cycle of about 11 years and on a maximum there are more solar flares. The last maximum was in 2000 and we were thus expecting a maximum around 2011, but as with other weather (terrestrial or not) predictions, there is a margin of error. So, I am sure you can go around doing your end of year celebrations without worrying about solar flares and who knows you may even have a chance to see a charming aurora!

If you want to ask a question to Quantum Tunnel use the form here.

Related Articles

'Extreme solar storm' could have pulled the plug on Earth - The Guardian

## Science is a creative process

I wanted to get things in perspective: If law students had to spend five or six years in school, think up a novel law and get i t passed. then their training would resemble that of a biology Ph.D. If a med student had to invent and test a new treatment for patients - and prove it successful - before being awarded an M.D., ditto. If my students remember nothing else, I'd be happy if they leave with the idea that, just like art or music, science is a creative process.

## ICM2014 ― opening ceremony

I’d forgotten just how full the first day of an ICM is. First, you need to turn up early for the opening ceremony, so you end up sitting around for an hour and half or so before it even starts. Then there’s the ceremony itself, which lasts a couple of hours. Then in the afternoon you have talks about the four Fields Medallists and the Nevanlinna Prize winner, with virtually no breaks. Then after a massive ten minutes, the Nevanlinna Prize winner talks about his (in this case) own work, about which you have just heard, but in a bit more detail. That took us to 5:45pm. And just to round things off, Jim Simons is giving a public lecture at 8pm, which I suppose I could skip but I think I’m not going to. (The result is that most of this post will be written after it, but right at this very moment it is not yet 8pm.)

I didn’t manage to maintain my ignorance of the fourth Fields medallist, because I was sitting only a few rows behind the medallists, and when Martin Hairer turned up wearing a suit, there was no longer any room for doubt. However, there was a small element of surprise in the way that the medals were announced. Ingrid Daubechies (president of the IMU) told us that they had made short videos about each medallist, and also about the Nevanlinna Prize winner, who was Subhash Khot. So for each winner in turn, she told us that a video was about to start. An animation of a Fields medal then rotated on the large screens at the front of the hall, and when it settled down one could see the name of the next winner. The beginning of each video was drowned out by the resulting applause (and also a cheer for Bhargava and an even louder one for Mirzakhani), but they were pretty good. At the end of each video, the winner went up on stage, to more applause, and sat down. Then when the five videos were over, the medals were presented, to each winner in turn, by the president of Korea.

Here they are, getting their medals/prize. It wasn’t easy to get good photos with a cheap camera on maximum zoom, but they give some idea.

Avila

Bhargava

Hairer

Mirzakhani

Khot

After those prizes were announced, we had the announcements of the Gauss prize and the Chern medal. The former is for mathematical work that has had a strong impact outside mathematics, and the latter is for lifetime achievement. The Gauss medal went to Stanley Osher and the Chern medal to Phillip Griffiths.

If you haven’t already seen it, the IMU page about the winners has links to very good short (but not too short) summaries of their work. I’m quite glad about that because I think it means I can get away with writing less about them myself. I also recommend this Google Plus post by John Baez about the work of Mirzakhani.

I have one remark to make about the Fields medals, which is that I think that this time round there were an unusually large number of people who could easily have got medals, including other women. (This last point is important — one should think of Mirzakhani’s medal as the new normal rather than as some freak event.) I have two words to say about them: Mikhail Gromov. To spell it out, he is an extreme, but by no means unique, example of a mathematician who did not get a Fields medal but whose reputation would be pretty much unaltered if he had. In the end it’s the theorems that count, and there have been some wonderful theorems proved by people who just missed out this year.

Other aspects of the ceremony were much as one would expect, but there was rather less time devoted to long and repetitive speeches about the host country than I have been used to at other ICMs, which was welcome.

That is not to say that interesting facts about the host country were entirely ignored. The final speech of the ceremony was given by Martin Groetschel, who told us several interesting things, one of which was the number of mathematics papers published in international journals by Koreans in 1981. He asked us to guess, so I’m giving you the opportunity to guess before reading on.

Now Korea is 11th in the world for the number of mathematical publications. Of course, one can question what this really means, but it certainly means something when you hear that the answer to the question above is 3. So in just one generation a serious mathematical tradition has been created from almost nothing.

He also told us the names of the people on various committees. Here they are, except that I couldn’t quite copy all of them down fast enough.

The Fields Medal committee consisted of Daubechies, Ambrosio, Eisenbud, Fukaya, Ghys, Dick Gross, Kirwan, Kollar, Kontsevich, Struwe, Zeitouni and Günter Ziegler.

The program committee consisted of Carlos Kenig (chair), Bolthausen, Alice Chang, de Melo, Esnault, me, Kannan, Jong Hae Keum, Le Bris, Lubotsky, Nesetril and Okounkov.

The ICM executive committee (if that’s the right phrase) for the next four years will be Shigefumi Mori (president), Helge Holden (secretary), Alicia Dickenstein (VP), Vaughan Jones (VP), Dick Gross, Hyungju Park, Christiane Rousseau, Vasudevan Srinivas, John Toland and Wendelin Werner.

He also told us about various initiatives of the IMU, one of which sounded interesting (by which I don’t mean that the others didn’t). It’s called the adopt-a-graduate-student initiative. The idea is that the IMU will support researchers in developed countries who want to provide some kind of mentorship for graduate students in less developed countries working in a similar area who might otherwise not find it easy to receive appropriate guidance. Or something like that.

Ingrid Daubechies also told us about two other initiatives connected with the developing world. One was that the winner of the Chern Medal gets to nominate a good cause to receive a large amount of money. Stupidly I seem not to have written it down, but it may have been $250,000. Anyhow, that order of magnitude. Phillip Griffiths chose the African Mathematics Millennium Science Initiative, or AMMSI. The other was that the five winners of the Breakthrough Prizes in mathematics, Donaldson, Kontsevich, Lurie, Tao and Taylor, have each given$100,000 towards a $500,000 fund for helping graduate students from the developing world. I don’t know exactly what form the help will take, but the phrase “breakout graduate fellowships” was involved. When I get time, I’ll try to write something about the Laudationes, but right now I need to sleep. I have to confess that during Jim Simons’s talk, my jet lag caught up with me in a major way and I simply couldn’t keep awake. So I don’t really have much to say about it, except that there was an amusing Q&A session where several people asked long rambling “questions” that left Jim Simons himself amusingly nonplussed. His repeated requests for short pithy questions were ignored. Just before I finish, I’ve remembered an amusing thing that happened during the early part of the ceremony, when some traditional dancing was taking place (or at least I assume it was traditional). At one point some men in masks appeared, who looked like this. Masked dancers Just while we’re at it, here are some more dancers. Dancers of various kinds Anyhow, when the men in masks came on stage, there were screams of terror from Mirzakhani’s daughter, who looked about two and a half, and delightful, and she (the daughter) took a long time to be calmed down. I think my six-year-old son might have felt the same way — he had to leave a pantomime version of Hansel and Gretel, to which he had been taken as a birthday treat when he was five, almost the instant it started, and still has those tendencies. Read me... ## Stochastic Calculus and Differential Equations for Physics and Finance Review of Stochastic Calculus and Differential Equations for Physics and Finance, by Joseph L. McCauley Download a free copy of the review here. Read me... ## Prof Simon Donaldson of Imperial College, London, wins 1.8 million pound prize #Maths Donaldson one of five to win most lucrative mathematics prize ever established Simon Donaldson received the 'Breakthrough'$3m (£1.8m) prize and trophy for "new revolutionary invariants of four-dimensional manifolds".

The Breakthrough prize in mathematics was established by Mark Zuckerberg (founder of Facebook) and Yuri Milner (internet entrepreneur) to encourage more widespread interest in the areas of science and mathematics.

In a Guardian interview Donaldson said of his win: "I was quite taken aback. I haven't had any time to think what I'll do with the money. It's hard to say what impact the prizes will have because they are so new. But one hopes they'll increase the prominence of the subject in general."

## Nature Materials: Focus Editorial Mexico

Back in October 2010, Nature Materials published a Focus Editorial on Mexico in which I contributed with Joerg Heber. You can find information about it here:

Focus issue:October 2010 Volume 9, No 10
Nature Materials:
http://www.nature.com/nmat/focus/mexico/index.html#ed

Mexico is a country rich with natural resources and an educated workforce. Yet its scientific output remains below its potential. In a focus issue we highlight some of Mexico's structural problems.

## Magnetic Resonance Imaging (MRI)

A few days ago I received a request from a reader (Thanks Paulo Zan) for information about magnetic resonance. The request did not specify more than that so I took the liberty of deciding that perhaps the request was due to coming across the term before and as such it is quite possible that a lot of us would have heard of magnetic resonance in the context of MRI scans.

Well, an MRI scan stands for "Magnetic Resonance Imaging" Scan and it is a widely-used technique to obtain images of the brain. The full name of the imaging technique is actually nuclear magnetic resonance imaging but it seems that the first word in that mouthful is sometimes avoided as it may have negative connotations for some. Other names include MRT or magnetic resonance tomography. MRI scanners use strong magnetic fields and radio waves to form images of the body.

As I mentioned above, the full name should include the word nuclear because the physical phenomenon exploited by the scanner is actually the absorption and emission of electromagnetic radiation by nuclei in a strong magnetic field. The absorption and emission of energy related to the frequency of the radiation in question and depending on the properties of the atoms, certain frequencies cause larger oscillations.Those frequencies are called resonance frequencies. An important feature of the phenomenon is that the resonance frequency of a particular substance is directly proportional to the strength of the applied magnetic field. In an MRI scanner it is this property the one that enables the imaging: if a sample is subjected to a non-uniform magnetic field then the resonance frequencies of the nuclei that make up the sample depend on where in the field they are located. The resolution of the images obtained depend on the  magnitude of magnetic field gradient and this strong fields are required. In a lot of scanners the detectors pick up radio signals emitted by excited hydrogen atoms in the body (remember that water is 2 parts hydrogen and 1 part oxygen). Due to the use of large magnets in the machines, the patients are required not to carry out metallic objects while in the same room as the scanner.

## Imágenes con Resonancia Magnética (MRI)

Hace unos días recibí una petición de un lector (Gracias Paulo Zan) para obtener información acerca de la resonancia magnética. La solicitud no especificó más que eso por lo que me tomé la libertad de decidir que tal petición debió haber iniciado al ver estos términos antes y, como tal, es muy posible que muchos de nosotros hemos oído hablar de la resonancia magnética en el contexto de la escáners de resonancia magnética (MRI por sus siglas en Inglés).

Bueno, la resonancia magnética es sinónimo de escaneo por Resonancia Magnética (Magnetic Resonance Imaging Scan) y es una técnica ampliamente utilizada para obtener imágenes del cerebro. El nombre completo de la técnica es en realidad "imágenes de resonancia magnética nuclear", pero parece que la última palabra en ese bocado se evita a veces ya que puede tener connotaciones negativas para algunos. Otros nombres incluyen MRT o la tomografía por resonancia magnética. Escáneres de resonancia magnética utilizan fuertes campos magnéticos y ondas de radio para formar imágenes del cuerpo.

## Science is beautiful exhibition

When I first heard about the plans that the British Library had about an exhibitions called Science is Beautiful I got very excited. I did even make an entry in my diary about the date that it was planned to be opened. Closer to the time I even encourage Twitter followers and colleagues to go to the exhibition.

The exhibition promised to explore how "our understanding of ourselves and our planet has evolved alongside our ability to represent, graph and map the mass data of the time." So I finally made some time and made it to the British Library today... the exhibition was indeed there with some nice looking maps and graphics, but I could not help feeling utterly disappointed. I was very surprised they even call this an exhibition, the very few images, documents and interactive displays were very few and not very immersive. Probably my favourite part was looking at "The Pedigree of Man" and the "Nightingale's Rose" together with an interactive show. Nonetheless, I felt that the British Library could have done a much better job given the wealth of documents they surely have at hand. Besides, the technology used to support the exhibits was not that great... for example the touch screens were not very responsive and did not add much to the presentation.

Sadly I cannot really longer recommend visiting the stands, and I feel that you are better off looking a the images that the Guardian has put together in their DataBlog, and complement with the video that Nature has made available. You can also read the review that Rebekah Higgitt wrote for the Guardian.

## Use of statistics...

Some people use statistics like a drunk uses a lamp-post, for support rather than illumination.

## Anti-atom beam

It may sound like a line from Star Trek, but I can assure you that the creation of a beam made out of anti-hydrogen atoms is a real achievement carried out by scientists at CERN.

The work was reported in Nature Communications, and it could hopefully help answering the question about the patent lack of anti-matter we see on everyday life. In order to study anti-matter we would need a source of them, plus the anti-particles should live long enough to make useful measurements.

It is not that anti-matter is not currently used, PET scans routinely employ positrons to take snapshots of patients bodies. But the prospect of having proper anti-matter atoms became a reality only about three years ago.  The recent announcement from the ASACUSA collaboration at CERN  Now scientists from a different collaboration at CERN, report the creation of a beam of anti-hydrogen atoms that can be measured more precisely outside the magnetic trap where they were created. At least 80 of the anti-atoms were detected, 2.7 meters (9 feet) downstream of the production region.

## Essential MATLAB and Octave

As probably some of you know, I am currently writing a book about MATLAB and Octave focussed at new comers to both programming and the MATLAB/Octave environments. The book is tentatively entitled "Essential MATLAB and Octave" and I am getting closer and closer to getting the text finished. The next step is preparing exercises and finalising things. My publisher, CRC Press, has been great and I hope the book does well.

I'm aiming to finish things by May and in principle the book will be available from Novemeber or so. The whole process does take a while but I am really looking forward to seeing the finished thing out there.

So, what triggered this post? Well, I have seen the appearance of a site with the book announced. I am not sure if these are usual practices but in any case it is a good thing, don't you think?

## Harvesting magnetic fields...

A few days ago I got a message from my mate Jorge Soto... always great to hear from him, particularly with New Year wishes and even better with an interesting question:

The question is related to the conversion of magnetic energy into electrical one and whether the process can be achieved in places such as the Van Allen radiation belt.

So, lets us take this by parts: First the magnetic to electric energy conversion. Well, according to the first law of thermodynamics energy cannot be "created or destroyed", but we can indeed convert it from one from to another one. It turns out that we can use some kinetic energy to move, say, a magnet. In turn this kinetic energy can be converted to electrical energy thanks to the properties of electromagnetism, in particular to the so-called Faraday's law. Faraday discovered that, when moving a permanent magnet into and out of a coil of wire, an electrical current was induced in the wire while the magnet was in motion.

Now, to the Van Allen radiation belt: the belt is part of the Earth's magnetosphere. Ok, ok... The magnetosphere is the part of space near a celestial object in which charged particles are controlled by the magnetic field generated by the object itself. So the Van Allen belts extend from an altitude of about 1,000 to 60,000 kilometers above the surface in which region radiation levels vary. In order to convert magnetic energy to electrical, as mentioned above, we requiere the magnetic field to be in movement or vary. It is generally accepted that in that context, the Earth is effectively a permanent magnet and thus to generate electric power from that, you have to move electric conductors (wires) thought the  field in the right direction and with the right orientation of the conductor. Not an easy task...

However, one can perhaps take advantage of the variations of the magnetic field. In Nature 439, 799-801 (16 February 2006) it has been reported that

"... Earth's magnetic field is weak: it varies from about 25 microtesla (T) at the Equator to 75 T at the poles, with geomagnetic field lines inclined, in Europe and North America, at an angle of about 60° to the (horizontal) surface. The field is not constant: currents in the ionosphere and disturbances from Earth's interior produce slow daily variations in the field with amplitudes of some 25 nanotesla (nT), and superimposed on these are further oscillations with periods of a few seconds and amplitudes of about 1 nT."

Using the very crude approximation that there are variations of 1nT per second, and take a circular area of with radius of 1 metre we would end up with a voltage of $latex pi times 10^{-9}$ Volts or approximately 3.1415 nano volts. Or in other terms we would get about 3 one-billionth's of a volt per square meter of flux... probably not a lot of usable energy and thus maybe not that cost effective.

## Wishful thinking or The Misuse of Maths in Psychology

The misuse of maths in psychology

"Think positively!" - a seemingly innocuous remark you might hear every so often… you might have even read it in one of those self-help books, or even from renowned psychologists of “positivity” such as Barbara Fredrickson. In 2005, Fredrickson and her colleague Marcial Losada published a paper in “American Psychologist” in which they calculate a “positivity ratio” using Lorenz equations.

In the paper, the authors mention that positivity ratios above 2.9013 are related to “flourishing mental health”. It turns out the this paper has recently been refuted and even partially withdrawn thanks to the judicious eye of Nicholas Brown, a part time graduate student from the University of East London who was able to see through the great misuse of mathematics. Brown was supported by Alan Sokal, an outspoken critic of postmodernism and professor of physics at New York University; and Harris L Friedman a clinical psychologist from Saybrook University and the University of Florida. Their paper is entitled “The Complex Dynamics of Wishful Thinking: The Critical Positivity Ratio.”

The Observer newspaper mentions that Fredrickson and Losada were given the opportunity of responding to the refutal… Only Fredrickson took the opportunity up. According to the Observer

“She effectively accepted that Losada's maths was wrong and admitted that she never really understood it anyway. But she refused to accept that the rest of the research was flawed.”

I guess is still the positive thinking that may be helping her…

It is great to see that the scientific process does work, unfortunately I am sure that the “positive ratio” pushers will continue to exploit the situation.

## IoP Talk

IoP Talk announced:
Thoery, model and simulation: An involved association
Jan 29th 2014, 19.00-20.00

## Nature's Readers choice of 2013

Keeping up with the well-established tradition of year-end lists, here is one from Nature's blog:

7 August 2013

19 June 2013

15 April 2013

22 February 2013

15 May 2013

16 May 2013

4 October 2013

14 January 2013

29 August 2013

## 10. Why has the Yangtze River turned red?

11 September 2013

## Grace Hopper Doodle

Once again Google puts out a doodle worth mentioning. This time they celebrate the 107th birthday anniversary of computer scientist Grace Hopper.
In case you do not know who Hopper is, well, let me smile say that she is the amazon woman behind COBOL (Common Business Oriented Language), which is still very much used today.

Grace Hopper was born in  New York in 1906  and studied Mathematics and Physics (of course) at Vassar College where she graduated in 1928. She then obtained a master's degree at Yale in 1930 and a PhD in 1934.

Hopper joined the US Navy reserve during World War two and she was assigned to the Bureau of Ordinance Computation Project at Harvard University where she was only the third person to program the Harvard Mark I computer. She continued to work at Harvard until 1949 when she joined the Eckert-Mauchly Computer Corporation as a senior programmer.

She helped to develop the UNIVAC I, which was the second commercial computer produced in the US. In the 1950s Hopper created the first ever compiler, known as the A compiler and the first version was called the A-O.

Hopper continued to serve in the navy until 1986 when she was the oldest commissioned officer on active duty in the United States Navy.

She died in Arlington, Virginia in 1992 at the age of 85.

## Google Doodle - Carlos Juan Finlay

Born on December 3rd 180 years ago, Carlos Juan Finlay is the man who came up with the theory that yellow fever was spread by mosquitoes. Glad to see that a Google Doodle can help with letting people know about this important Cuban scientist.

Finlay's research on cholera and yellow fever didn't initially get much support. He suggested that yellow fever was carried by mosquitos and he suggested that cholera was waterborne. His work was proven later by the Walter Reed Commission and in 1902 Finlay became the chief health officer in Cuba. This confirmation paved the way for the eradication of yellow fever, creating the chance to save thousands of lives.

## The Way of All Flesh

The Way of All Flesh by Adam Curtis: a one-hour BBC documentary on Henrietta Lacks and HeLa directed by Adam Curtis. It won the Best Science and Nature Documentary at the San Francisco International Film Festival. Immediately following the film's airing in 1997, an article on HeLa cells, Lacks, and her family was published by reporter Jacques Kelly in The Baltimore Sun.

## What Science's "Sting Operation" reveals - reblog

This is a re-blog of "What Science's "Sting Operation" Reveals" by Kausik Datta in Scilogs.

# What Science’s “Sting Operation” Reveals: Open Access Fiasco or Peer Review Hellhole?

4 October 2013 by Kausik Datta,

The science-associated blogosphere and Twitterverse were abuzz today with the news of a Gotcha! story published in today's Science, the premier science publication from the American Association for Advancement of Science. Reporter John Bohannon, working for Science, fabricated a completely fictitious research paper detailing the purported "anti-cancer properties of a substance extracted from a lichen", and submitted it under an assumed name to no less than 304 Open Access journals all over the world, over a course of 10 months. He notes:

... it should have been promptly rejected. Any reviewer with more than a high-school knowledge of chemistry and the ability to understand a basic data plot should have spotted the paper's short-comings immediately. Its experiments are so hopelessly flawed that the results are meaningless.

Nevertheless, 157 journals, out of the 255 that provided a decision to the author'snom de guerre, accepted the paper. As Bohannon indicates:

Acceptance was the norm, not the exception. The paper was accepted by journals hosted by industry titans Sage and Elsevier (Note: Bohannon also mentions Wolters Kluwer in the report). The paper was accepted by journals published by prestigious academic institutions such as Kobe University in Japan. It was accepted by scholarly society journals. It was even accepted by journals for which the paper's topic was utterly inappropriate, such as the Journal of Experimental & Clinical Assisted Reproduction.

This operation, termed a 'sting' in Bohannon's story, ostensibly tested the weaknesses, especially poor quality control exercised, of the Peer Review system of the Open Access publishing process. Bohannon chose only those journals which adhered to the standard Open Access model, the author pays if the paper is published. When a journal accepted either the original, or a revised (superficially, retaining all the fatal flaws) version, Bohannon sent an email requesting to withdraw the paper citing a 'serious flaw' in the experiment which 'invalidates the conclusion'. Bohannon notes that about 60% of the final decisions appeared to have been made with no apparent sign of any peer review; that the acceptance rate was 70% after review, only 12% of which identified any scientific flaws - and about half of them were nevertheless accepted by editorial discretion despite bad reviews.

As noted by some scientists and Open Access publishers like Hindawi whose journals rejected the submission, the poor quality control evinced by this sting is not directly attributable to the Open Access model. A scientific journal that doesn't perform peer review or does a shoddy job of it is critically detrimental to overall ethos of scientific publishing and actively undermines the process and credibility of scientific research and the communication of the observations thereof, regardless of whether the journal is Open Access or Pay-for-Play.

And that is one of the major criticisms of this report. Wrote Michael B Eisen, UC Berkeley Professor and co-founder of the Public Library of Science (PLoS; incidentally, the premier Open Access journal PLOS One was one of the few to flag the ethical flaws in, as well as reject, the submission) in his blog today:

... it’s nuts to construe this as a problem unique to open access publishing, if for no other reason than the study didn’t do the control of submitting the same paper to subscription-based publishers [...] We obviously don’t know what subscription journals would have done with this paper, but there is every reason to believe that a large number of them would also have accepted the paper [...] Like OA journals, a lot of subscription-based journals have businesses based on accepting lots of papers with little regard to their importance or even validity...

I agree. This report cannot highlight any kind of comparison between Open Access and subscription-based journals. The shock-and-horror comes only if one places a priori Open Access journals on a hallowed pedestal for no good reason. For me, one aspect of the revealed deplorable picture stood out in particular - the question: Are all Open Access Journals created equal? The answer to that would seem to be an obvious 'No', especially given the outcome of this sting. But then it would beg the follow-up question, if this had indeed been a serious and genuine paper, would the author (in this case, Bohannon) seek out obscure OA journals for publishing it?

As I commented on Prof. Eisen's blog, rather than criticizing the Open Access model, the most obvious solution to ameliorate this kind of situation seems to be to institute a measure of quality assessment for Open Access journals. I am not an expert in the publishing business, but surely some kind of reasonable and workable metric can be worked out in the same way Thomson Reuters did all those years ago for Pay-for-Play journals? Dr. Eva Amsen of the Faculty of 1000 (and an erstwhile blog colleague at Nature Blogs) pointed out in reply that a simple solution would be to quality control for peer review via an Open Peer Review process. She wrote:

... This same issue of Science features an interview with Vitek Tracz, about F1000Research’s open peer review system. We include all peer reviewer names and their comments with all papers, so you can see exactly who looked at a paper and what they said.

Prof. Eisen, a passionate proponent of the Open Access system and someone who has been trying for a long time to reform the scientific publishing industryfrom within, agrees that more than a "repudiation [of the Open Access model] for enabling fraud", what this report reveals is the disturbing lesson that the Peer Review system, as currently exists, is broken. He wrote:

... the lesson people should take home from this story not that open access is bad, but that peer review is a joke. If a nakedly bogus paper is able to get through journals that actually peer reviewed it, think about how many legitimate, but deeply flawed, papers must also get through. [...] there has been a lot of smoke lately about the “reproducibility” problem in biomedical science, in which people have found that a majority of published papers report facts that turn out not to be true. This all adds up to showing that peer review simply doesn’t work. [...] There are deep problems with science publishing. But the way to fix this is not to curtain open access publishing. It is to fix peer review.

I couldn't agree more. Even those who swear by peer review must acknowledge that the peer review system, as it exists now, is not a magic wand that can separate the grain from the chaff by a simple touch. I mean, look at the thriving Elsevier Journal Homeopathy, allegedly peer reviewed... Has that ever stemmed the bilge it churns out on a regular basis?

But the other question that really, really bothers me is more fundamental: As Bohannon notes, "about one-third of the journals targeted in this sting are based in India — overtly or as revealed by the location of editors and bank accounts — making it the world's largest base for open-access publishing; and among the India-based journals in my sample, 64 accepted the fatally flawed papers and only 15 rejected it."

Yikes! How and when did India become this haven for dubious, low quality Open-Access publishing? (For the context, see this interactive map of the sting.)

## Hawthorne Effect

I was listening last week to the "More or Less" podcast with Tim Harford, which by the way is one of my favourite Radio 4 programmes and I highly recommend it. In the programme they were discussing the proposal of Mr Nick Clegg, the UK's Deputy Prime Minister, to offer free school lunches to all pupils at infant schools. The proposal follows from a pilot study  that seemed to suggest that giving free meals to school children was good for their academic performance.

As usual, not all is what it seems and the programme goes on to discuss this. I'm afraid is the old adage of correlation and causation... In any case, the commentators in the programme made a reference to the Hawthorne effect, and although Tim Harford mentioned something about this I ended up with the curiosity to find out more about it. It turns out that the Hawthorne effect is at work when subjects modify and change their behaviour in response to the fact that they know they are being studied. You might think that this is similar to the quantum mechanical observer affecting the system they observe, except that in this case the system is patently aware of the influence of the observation. I would leave it at that...

The effect is named after Western Electric’s  Hawthorne Works in Cicero, Il somewhere close to Chicago. Between 1924 and 1932 Elton Mayo carried out some productivity trials that have become some of the most well-know in social science, as the study is often held as a demonstration that people respond to change when they know you they are being observed or studied. So, who knows, perhaps the pupils, parents and teachers did indeed change their behaviour while the study was taking place... Oh well...

## Electromagnetism redefined?

I have finally had some time to catch up with the brand new Observer Tech Monthly magazine, a very welcomed addition to the fine Guardian and Observer newspapers. So, there I was, reading about Paul Mason and his tech, and how the body clock works. So, after a turn of the page I find an article by Alok Jha explaining Maxwell's Equations and how they electrified the world. All great, except... except... well... except the equations they framed (as expected written with chalk on a blackboard) are incorrect. OK, at least one of them is incorrect , but that it enough to redefine the entire electromagnetic theory.

They have started by showing the equations for the case of a region with no charges ($latex \rho = 0$) and no currents ($latex J = 0$), such as in a vacuum. The correct set of Maxwell's equations reduce in that case to:

• $latex \nabla \cdot {\bf E}=0$
• $latex \nabla\cdot {\bf B}=0$
• $latex \nabla\times {\bf E}=-\frac{\partial {\bf B}}{\partial t}$
• $latex \nabla\times {\bf B}=\frac{1}{c^2}\frac{\partial {\bf E}}{\partial t}$

I have used the notation $latex {\bf B}$ for the magnetic field... In any case, note the last two equations I wrote above. Can you see the difference between them and the ones depicted in the newspaper article? I wonder what sort of electromagnetic phenomena could be observed by the redefined equations in the Observer... who knows perhaps that is the way electromagnetic fields behave in another Universe, but not on this one.

## Léon Foucault celebrated in a Google Doodle

If you encountered a pendulum going round in the Google page this morning it is because the Google Doodle is celebrating the birthday of Jean Bernard Léon Foucault, a French physicist and inventor of a pendulum that demonstrated the rotation of the earth.

Among other things he is credited with making an early measurement of the speed of light. Foucault was born in Paris in 1819, where he initially studied medicine but soon switched to physics (hurray!). He demonstrated his 67-metre, 28kg pendulum at the Panthéon in Paris in 1851. The plane of motion of the pendulum with respect to the earth, rotated slowly clockwise.

## Suggestions of iPad apps for university mathematics teaching

This is a re-blog of the original entry by Peter Rowlett in the Aperiodical blog.

## PDF/screen annotation

For PDF import, annotation and export, Stu Price recommended using Notability. Theron Hitchman also recommended Notability for marking PDFs, NoteShelf for taking notes and SketchBook Pro for drawing. Jesus Rogel-Salazar recommended DocAS, saying the free version is “pretty good”, and mentioned having tried Penultimate too. Christian Bokhove recommended iAnnotate PDF. Christian also mentioned MathPen, which is the PhD project of Mandy Lo, who he co-supervises.

## Recording

On recording, Stu Price mentioned ExplainEverything, also recommended by Christian Bokhove.

Kevin Clift said:

You might be able to use the video playback feature intended for replaying the creation of a work of graphic art in Brushes to replay your handwriting. It seems to have an extensive memory but since it isn’t intended for the purpose of playing back handwriting you would want to try it out. Since most of it is free that should be easy to do.
EDIT: It seems that Procreate has just added a similar feature.

Jesus Rogel-Salazar pointed out a blog post by Amit Agarwal: ‘How to Record Screencast Videos on your iPad or iPhone‘.

## LaTeX

Stu Price recommended TeX Writer for writing LaTeX on the go. Theron Hitchmanrecommended TexPad for the same thing, mentioning that a bluetooth keyboard is a good idea for this. Jesus Rogel-Salazar recommended cloud-based LaTeX client writeLaTeX.

## Calculators

For calculators, Christopher Rath recommended TI-Nspire as “mathematically extensive but quite expensive at ~£20″. Edward Shore pointed out that this is much cheaper than the physical calculators themselves. Stu Price mentioned the Desmos Graphing Calculator, but hasn’t tried it yet, and PocketCAS which is apparently “quite neat with 3D surfaces”.

## Presenting

Jesus Rogel-Salazar recommended 2Screens for presenting.

## Assessment

For assessment, Stu Price recommended Socrative for quizzing/polling and mentioned iDoceo as a ‘gradebook’.

## Other

Christian Bokhove recommended Nearpod, which according to its App Store entry, “enables teachers to use their iPads to manage content on students’ iPads”, and Evernote.

Theron Hitchman recommended ThinkBook as “a fancy todo list/planner”.

There was also a comment on the previous post recommending MathPad, apparently by the company that makes the app.

Joerg Fliege pointed out two articles: ‘Apps for academics: mobile web sites & apps‘ at MIT Libraries and ‘8 Apps That Make Academic Research Easier‘ at Mac Life.

## Relating Airy and Bessel functions

Reblogged from The Endeavour by J. D. Cook.

The Airy functions Ai(x) and Bi(x) are independent solutions to the differential equation

For negative x they act something like sin(x) and cos(x). For positive x they act something like exp(x) and exp(-x). This isn’t surprising if you look at the differential equation. If you replace xwith a negative constant, you sines and cosines, and if you replace it with a positive constant, you get positive and negative exponentials.

The Airy functions can be related to Bessel functions as follows:

and

Here J is a “Bessel function of the first kind” and I is a “modified Bessel function of the first kind.” Also

To verify the equations above, and to show how to compute these functions in Python, here’s some code.

The SciPy function airy computes both functions, and their first derivatives, at once. I assume that’s because it doesn’t take much longer to compute all four functions than to compute one. The code for Ai2 and Bi2 below uses np.where instead of if... else so that it can operate on NumPy vectors all at once. You can plot Ai and  Ai2 and see that the two curves lie on top of each other. The same holds for Bi and  Bi2 .

from scipy.special import airy, jv, iv
from numpy import sqrt, where

def Ai(x):
(ai, ai_prime, bi, bi_prime) = airy(x)
return ai

def Bi(x):
(ai, ai_prime, bi, bi_prime) = airy(x)
return bi

def Ai2(x):
third = 1.0/3.0
hatx = 2*third*(abs(x))**1.5
return where(x > 0,
third*sqrt( x)*(iv(-third, hatx) - iv(third, hatx)),
third*sqrt(-x)*(jv(-third, hatx) + jv(third, hatx)))

def Bi2(x):
third = 1.0/3.0
hatx = 2*third*(abs(x))**1.5
return where(x > 0,
sqrt( x/3.0)*(iv(-third, hatx) + iv(third, hatx)),
sqrt(-x/3.0)*(jv(-third, hatx) - jv(third, hatx)))

There is a problem with Ai2 and Bi2: they return nan at 0. A more careful implementation would avoid this problem, but that’s not necessary since these functions are only for illustration. In practice, you’d simply use airy and it does the right thing at 0.

## Eigenvectors and Eigenvalues

I was talking to some students the other day (actually... a couple of months ago... ahem...), they had some questions about some problems on linear algebra and after a short while it became clear that they had mastered some of the techniques to deal with matrices and transformations, but sadly they had no idea about some of important concepts. The discussion moved into what the importance was for Eigenvectors and thus Eigenvalues. They could not answer, other than... "the way to calculate the Eigenvalue is...". So I decided to do an entry here about why we are interested in these things (other than to pass the exam...).

Let me start by the origin and meaning of the word Eigen: it comes from German and it is a prefix that can be translated as "proper", "own", "particular". That perhaps hints at the mathematical meaning, which could be even translated as "characteristic", which was first used by David Hilbert (I believe...). Some times Eigenvectors are thus called "Proper Vectors" although that is not my personal preference.

If we consider a collection of numbers arranged in $latex n$ rows and $latex n$ columns, i.e. a square matrix that we will call $latex \bf{A}$. Let us also consider a column vector $latex \bf x$ with $latex n$ non-zero elements. We can therefore carry out the matrix multiplication $latex \bf{Ax}$. Now we raise the following question: Is there a number $latex \lambda$ such that the multiplication $latex \lambda \bf x$ gives us the same result as $latex \bf Ax$. In other words: $latex \bf{Ax} = \lambda \bf x$, if so, then we say that $latex \lambda$ is an Eigenvalue of $latex \bf A$ and $latex \bf x$ is the Eigenvector. Great! That part is fine and we can compute these quantities, but why are we interested in this? Well, it turns out that many applications in science and engineering rely on linear transformations, which in turn use Eigenvectors and Eigenvalues. A linear transformation is a function between two vector spaces that preserves the operations of addition and scalar multiplication. In simpler terms, a linear transformation takes, for example, straight lines into straight lines or to a single point, and they can be used to elucidate how to stretch or rotate an object, and that is indeed useful.

So, where do Eigenvectors and Eigenvalues come into place? Well, they make linear transformations easier to understand. Eigenvectors can be seen as the "directions" along which a linear transformation stretches (or compresses), or flips an object, whereas Eigenvalues are effectively the factors by which such changes occur. In that way, Eigenvalues characterise important properties of linear transformations, for example whether a system of linear equations has a unique solution, and as described above, it can also describe the physical properties of a mathematical model.

Do you want a concrete example in which this is used on daily life? Well, have a look at PageRank used by Google...

## I'm a doctor... just not a medical one...

I could not help smiling widely as I was leaving that shop earlier on today... Why? Well, I was there to buy some bits and pieces. I arrived listening to some music and once inside the shop I hang my headphones around my neck. When I approached the counter the following conversation happened:

- "Is that all, love? Have you got a loyalty card?" - She asked

- "That's all, thanks. No, I don't have a loyalty card" - I replied

- "Oh, are you a doctor?" - She said

- "Ehhh?!" - I muttered, wondering how she knew... then realising she had mistaken my headphones by a stethoscope.  - "Oh, well, no..." -  I continued - "... well yes, I'm a doctor, just not a medical one" - I eventually replied.

- "Mmm, so what sort of doctor are you then?" - she queried

- "I'm a physicist..." - I shyly responded.

- "Oh really" -  said the customer next to me - "have you watched 'The Big Bang Theory'? It's very funny".

- "Yes, I have..." - I said - "very funny, yes... sometimes too close to home" - I confided.

- "Really?" - exclaimed both of them at the same time, with the customer adding "oh how exciting!!".

- "Yes... oh well, thanks. Catch you later" - I said as I was leaving the place.

## Backwards and Forwards in Time

Time flies, time is money, time is a wise counsellor, time is relative, time is... very hard to define. Paraphrasing St Augustine I can say that  I know what time is if no one asks me, but if I try to explain it I simply do not know. It seems to be very natural to acknowledge the passing of time, however when we take a moment to think about its meaning, we quickly find ourselves with a few problems.
We start by arguing that time can be defined by the interval between two successive events and thus we need a ruler to measure that interval. This is indeed a quest that us humans have pursued since the dawn of civilisation; it is very easy to see how the definition of day comes about: it is the interval between two successive sunrises. Once we have this in place a lot follows effortlessly: on the one hand we can start taking smaller intervals and define hours, minutes, seconds, and on the other, it is now possible to refer to events taking place in the past, the present and even the future. The ordering of these three concepts is intuitive as time flows from the past to the future, and we even see it manifested in the objects around us. We can imagine that we go to a museum where a film installation is being shown. The film starts with a large red stain in an otherwise immaculately white carpet. The camera spans and we see some pieces of glass strangely being attracted to each other while the red stain starts to shrink. The next thing we see is a wine glass appear before our eyes and wine droplets jump into it as if by magic. It is immediately obvious that the film was played in reverse as there seems to be a natural “forward direction”. This directionality is often referred to as the arrow of time and whenever it is discussed the subject of causality arises, and even time travel.

When I mention causality I am referring to the relationship between causes and effects; in the case of the film I used as an example, the cause of the spill is shown to us as artist hits the wine glass. When the film is shown in reverse, we tangibly notice that there is something missing: the glass cannot "unbreak" out of its own accord. What does physics have to say about this? If we were to analyse the film using the laws of motion described by Newton, we would find that there is no difference between the forward and backward directions. In other words, time reversal is not prohibited anywhere in Newtonian mechanics. This means that, given a present state under specific conditions, we are therefore able to predict the future, but also retrodict the past, as there is no distinction between the two. This sounds surprising as this sort of thing does not happen in our daily lives.

Scientists have come up with their own versions of the wine glass film described above. In one case, they have taken two particles of light, known as photons, with certain energies and mashed them together; after the collision they observed a pion and a deuteron as a result of the collision. Do not be too concerned about what these two new particles are, this will not affect the discussion. When the film is reversed, it shows a pion and a deuteron colliding and producing as a result two photons. This new experiment has been realised and lo and behold the physicists observed the generation of the two photons as predicted, giving them a confirmation that the laws that govern these phenomena do not change when time is reversed. As you may have noticed, we have blatantly ignored the present, and this is because we think of it as a transitory state between the past and the future. In other words, the past is gone while the future has not arrived, and the ephemeral present expires as soon as we try thinking of it.

From this point of view, the result of these experiments seems to indicate that the arrow of time is embedded in our perception. It has been argued that the arrow of time is a psychological effect, and that this feeling that time flows mercilessly from the past to the future is all subjective. Let us take these arguments a step further, if indeed there is no difference between past and future, then there is nothing stopping us from travelling to the future (as we imminently do) or to the past (as we clearly are not). Believe it or not, but physics has something to tell us about this. I mentioned above that time reversal is allowed by Newtonian mechanics, so why can we not put together again the wine glass by time reversing the process, rather than supergluing the broken pieces? The answer is not in the realm of mechanics, but in that of thermodynamics, in other words the study of how energy converts between heat and other forms of energy. In that manner, physicists also talk about a thermodynamic arrow of time, in the sense that a given physical system invariably becomes ever more disordered, and since disorder is therefore important we quantify it with a quantity called entropy. This rule that tells us that entropy increases with time is known as the second law of thermodynamics. Following this line of thought, we are not allowed to fix our broken wine glass by running time backwards because it would imply going from a more disordered state to a more ordered one without using any extra energy, and so travelling to the past is not an easy task to achieve.
What about travelling to the future, or in the direction pointed by entropy? Well, in that case there is certainly nothing that stops us in our tracks. In fact, as I pointed out earlier on, we are already travelling to the future, and we do that at a pace of sixty minutes an hour. However, if we wanted to travel to the future at a different rate, Einstein's theory of relativity gives us a recipe to achieve this. In the so-called special theory of relativity the world has four dimensions: the usual three space dimensions that we know and love, i.e.. length, width and height; and one dimension that is related to time. In other words, when you walk from one place to another in the gallery where the wine glass video is being shown, you automatically change your position on the time coordinate, even if you don't notice. Einstein tells us that if we were to travel at the speed of light, time expands from the perspective of a stationary observer, whereas space contracts from the point of view of the moving person. This brings into question the notion of simultaneity, as two events that seem to happen at the same time for the stationary person, could in principle happen at different times from the point of view of the moving person. It is fascinating to compare Einstein’s efforts to unravel the secrets of simultaneity in time, with Picasso’s cubism to depict simultaneity in space. The effect of time dilation has been experimentally confirmed with very precise caesium clocks. Unfortunately, it is completely outside of human experience, because we have not yet devised a way of travelling at speeds where relativistic effects become noticeable. Even if we were to spend our entire lives in a plane that moves at supersonic speed, we would barely win a second over our contemporaries on the ground.

So, time travel as presented to us in sci-fi films is not yet possible but that has not stopped us from imagining its consequences. As for the definition of time, I am sure that there are many other things that can be said on the subject. Unfortunately, time is a merciless master, and that is all the time and space I have for now.

Dr Jesús Rogel-Salazar
(originally appeared in Artesian : Issue Three : Time : 2011)

## "Death Ray" in Las Vegas - or the Hottest Spot in Las Vegas Strip

I first heard this in a talk by Miguel Alonso in the School on Modern Optics at INAOE earlier on in May. I still think it is hilarious... seriously hilarious...

It turns out that in an effort to keep their recent building cool, the Vdara hotel in Las Vegas has come up with the idea of "energy-efficient" windows. 'How do they work?' do I hear you scream? Well, they are mirrored windows. The idea being that the desert Sun light is reflected out keeping the heat down inside the building... That would all be fine except that they have made the building curved and as such the entire 57-foot curved mirror is working as lens concentrating the light... The solar reflection is so strong that it has been dubbed the "Death Ray" hotel as it has already caused severe burns...

After posting this, I got to hear about a parody trailer for "Fryline"...

## Twin Primes and the Ternary Goldbach Conjecture

Just like buses... exactly just like buses... you wait for one and two come all at once. That is exactly what I thought when I heard about the two results in number theory that came up almost at the same time. One by Yitang Zhang, of the University of New Hampshire in relationship to twin primes, and the other one by Harald Andrés Helfgott of École Normale Supérieure - Paris about the ternary Goldbach conjecture. So what are these things?

## Twin Primes

Well Yitang Zhang's paper in Annals of Mathematics, entitled "Bounded gaps between primes" deals the question as to how close  two prime numbers are. The Twin Prime Conjecture states that there are an infinite number of primes $latex p$ and $latex q$ that are as close as possible: $latex p-q=2$. (ahem... I know, some of you are already raising your hands saying that 2 and 3 are closer, but that can only happen once...). Some attribute the conjecture to the Greek mathematician Euclid of Alexandria, which would make it one of the oldest open problems in mathematics. And Zhang has tackled the problem head on by showing that there are an infinite number of primes $latex p$ and $latex q$ such that $latex p-q=2N$, where $latex N$ is a bounded constant. The new result therefore shows that there are infinitely many pairs of primes that are less than 70 million units apart without relying on unproven conjectures. It may seem that 70 million is way to large a number, not compared to infinity! This means that the gaps between consecutive numbers don’t keep growing forever.

## The Ternary Goldbach Conjecture

Keeping with prime numbers, they are indeed of much interest as they can be seen as the "atoms of arithmetic" as other number can be expressed as factorisation of prime numbers. In that sense, prime numbers are intimately related to multiplication, but there are additive properties that they do have. The Goldbach conjecture proposes that every even number is the sum of two primes and Harald Andrés Helfgott settled the matter of a weaker version of the conjecture. You can have a look at his paper entitled "Major arcs for Goldbach's problem" here. The statement that Helfgott  provided a proof for us that every odd integer $latex n>5$ is the sum of three primes. Although Helfgott’s paper has not yet been formally published or peer-reviewed, it has been endorsed by Terrence Tao, who was close to resolving the problem last year.

## Yuletide Disquisitions?? Come on!

I twitted earlier this week an Open Letter to the Royal Institution by Ian Gent in response to the bizarre and quite frankly ludicrous decision by the RI to trademark the term "Christmas Lectures". I agree with the points made by Ian as well as others (see here and here). I find it quite offensive to the scientific and science communication communities to make it illegal to use the term Christmas Lecture if you happen to organise an event where a lecture will be given during the Christmas period... I suppose people will have to start organising Yuletide Disquisitions...

## Quantum Leap... Are you sure you mean that?

I have been meaning to write this post for a while, but for one reason or another (or rather many reasons...) I had not been able to. Right, so what has triggered this post? Well, I was having a look at a the BFI website as they usually have some very good films and event to attend and I happened to come across some news about Film Nation's new programme on film education. You can have a look at the website here. Did you click on the link? Have you seen the title of the news item? If not, please take a look at the screenshot I include in this post.

That is right! They describe the new programme as a "quantum leap for film education". I believe they want to imply that the programme is a great advancement, but I am not sure that describing it as a "quantum leap" conveys what they want. It is rather sad to see this sort of misuses and that is why I am writing this post.

So, a quantum is indeed a unit: it is the smallest amount of energy that a system can gain or lose, and this actually contradicts the message they want to communicate. The term "quantum" started being used in the early 1900s by Max Plank as part of a theory to explain the physics of the sub-atomic world. As such, light was thought as a tiny packet of energy (as well as a wave...) that could be emitted or absorbed by an electron in an atom for instance. As such a quantum leap is the smallest possible change in the energy level of that electron, and one that can take place at random.

So, who knows, perhaps the BFI (as well as others out there) do mean indeed to use "quantum leap" to describe these achievement... Or what do you think? Let me know and if you have any similar terms that get misused get in touch.

## Listen as Albert Einstein Reads ‘The Common Language of Science’ 1941 | Open Culture

Have you ever wondered how Albert Einstein sounded? Well here you have an opportunity to find out. In the link above there is a recording of Einstein reading an essay (in English) called "The Common Language of Science".

Enjoy!

## Copernicus celebrated - 540th Birthday Anniversary

I was planning to post this yesterday, but for one thing or another I forgot… Anyway, yesterday Nicolaus Copernicus would have been celebrating his 540th birthday. Copernicus is well known for Heliocentrism, i.e. the idea that the Earth orbits the Sun. At the time he proposed his idea without the aid of any equipment and he was (of course) branded as a heretic along the way. It was not until Galileo used his new telescope that the idea was proved right… The acceptance of which would take longer, and in the meantime Galileo would as well be called a heretic too…

I was therefore quite pleased to see the doodle that Google used yesterday to commemorate Copernicus. The doodle shows the planets of the Solar system orbiting their parent star. Happy birthday Copernicus.

## Elliptical Answers to Why Winter Mornings Are So Long - Rebloged from NYTimes.com

Reblogged from Elliptical Answers to Why Winter Mornings Are So Long - NYTimes.com by John O'Neil.

As the parent of teenage boys who have to be dragged out of bed on school days, I had been looking forward to earlier sunrises once the winter solstice was past. But early January mornings seemed darker than ever while at the same time, the sky was clearly lighter around 5 p.m.

###### Tony Cenicola/The New York Times

FIGURE 8 An analemma shows the Sun’s varying positions over a year.

It turned out that what I suspected was actually true — by Jan. 2, there were 12 more minutes of sunlight in the afternoons, but 3 fewer minutes in the morning. It also turned out that the reasons for it were complicated, as I discovered in a series of phone and e-mail conversations with Jay M. Pasachoff, a professor of astronomy at Williams College, and a former student of his, Joseph Gangestad, who received his Ph.D. in orbital mechanics from Purdue.

They pointed me to the Equation of Time, a grandly named formula relating to the fact that not all days are 24 hours, if you track noon by the position of the Sun instead of on a clock.

We’ve all seen a readout of the Equation of Time, Dr. Pasachoff said. It’s that uneven figure 8 that can be found on globes in a deserted part of the Pacific, a shape known as an analemma.

If Earth’s axis were perpendicular to its orbit instead of tilted, and if its orbit were a circle instead of an ellipse, the Sun would appear in the same spot in the sky each day and clocks and sundials would always match. Instead, they can be as much as 16 minutes apart, and that’s where things get complicated.

As Earth moves toward winter solstice, you have “different things going on at the same time,” Dr. Pasachoff said.

Earth’s tilt means that every day during the fall, the angle at which we view the Sun changes. It appears farther south and travels a shorter arc across the sky, affecting sunrise and sunset equally, and making the day shorter.

The changes in the solar time follow a different cycle. In the early 1600s, Kepler discovered that planets move faster at the part of their orbit that is closest to the sun, the perihelion. For Earth, perihelion comes a little after the winter solstice, so from November on, Earth is accelerating.

That increased speed means we reach the Sun’s maximum a little earlier each day, which pushes solar noon backward against clock time. That shift is amplified because the Sun is traveling a little south each day, while clocks only count its east to west traverse.

Add it all together and you get sunrise and sunset times that are not symmetrical. In the weeks before the winter solstice, sunrise is being pushed later by both the changing angle of the Sun and the slowing of solar time. But sunset is being pushed in both directions — earlier by the Sun’s angle and later by the change in solar time.

The result is more darkness in the morning and less in the afternoon. That’s why the earliest sunset of 2012, at 4:29 p.m., in New York fell as soon as Nov. 30, according to theNational Oceanic and Atmospheric Administration’s solar calculator, while mornings continued to stay dark later. After the solstice, Earth continued its acceleration until reaching perihelion on Jan. 2. So the sunrise continued to slide, reaching its latest point, 7:20 a.m., on Dec. 28. There it stood until Jan. 11, when we finally got another minute of morning light. By Feb. 7, sunrise will be all the way back to 7 a.m.

“It’s hard to wrap the mind around this problem, which is really a figment of our timekeeping system,” Dr. Gangestad said. That is, we would never notice it if we all just used sundials.

## The Swanson Effect

Solar energy currently provides only a quarter of a percent of the planet’s electricity supply, but the industry is growing at staggering speed. Underlying this growth is a phenomenon that solar’s supporters call Swanson’s law, in imitation of Moore’s law of transistor cost. Moore’s law suggests that the size of transistors (and also their cost) halves every 18 months or so. Swanson’s law, named after Richard Swanson, the founder of SunPower, a big American solar-cell manufacturer, suggests that the cost of the photovoltaic cells needed to generate solar power falls by 20% with each doubling of global manufacturing capacity. The upshot is that the modules used to make solar-power plants now cost less than a dollar per watt of capacity. This means that in sunny regions such as California, photovoltaic power could already compete without subsidy with the more expensive parts of the traditional power market. Moreover, technological developments that have been proved in the laboratory but have not yet moved into the factory mean Swanson’s law still has many years to run.

## Mirror mirror, right and left, up and down

You are getting ready for the New Year's party and cannot help to use a mirror to check that all is spot on. The tie is straight, the hair is tamed, the shoes are polished but wait... right is wrong, or rather right is left and left is right... but up is still up and down is down. Why, you ask, do mirrors reverse right and left but not up and down? Well, the answer is that they do not do either of them. They reverse front to back...

The image that you see in front of you has not been swapped, but inverted along the axis of the mirror. So the answer to this question can be understood with looking at how light gets reflected. If we consider a light source, its rays will bounce off various parts of your body, they will reflect off the mirror and will be caught by your eyes; plus we know consider that for all intents and purposes light travels in a straight line. And so, a mirror (not a fun fair mirror by the way) will simply reflect what is in front of it: the light bouncing of your right hand  will hit the mirror straight on and then will bounce into your eye. What you will perceive is that you see your right hand in the place of the left one. And notice that it is a matter of perception... Now, try the following: position yourself looking North and place the mirror in front of you. Now point at something East with your right hand, you will see that the hand in the mirror will also point East; the same happens if you point West with your left hand. So the directions are fine: East is East and West is West. But look at your nose, it points North, right? What about the nose in the image? Well, it points South! The image is reverted front to back.

Richard Feynman provides this explanation to the BBC TV Series "Fun to Imagine" in 1983.

Now, you have something to think about next time you are getting ready in front of the mirror.

I know that strictly speaking there should not be an entry for December 25th in the Sci-advent, but to tell you the truth I could not help myself and decided to do one more. This time it is about parthenogenesis: Parthenos  (παρθένος), meaning virgin in Greek and Genesis (γένεσις), meaning birth. The name Parthenos appears for instance in Greek mythology in the story of the daughter of Apollo and Chrysothemis , who died a maiden and was placed among the stars as the constellation of Virgo (fittingly enough...).

Almost all animal species reproduce sexually, by mixing the genes of two different individuals from meiosis. About 1% of animal species reproduce by parthenogenesis, while an even smaller fraction switch between sexual and asexual reproduction (known as cyclical parthenogenesis). One method of parthenogenesis involves sex cell division and recombination, while another just produces an egg with a full complement of DNA. Parthenogenesis is known to happen in some species of fish, amphibians and reptiles... but not in humans...

## Chromosomes - Sci-advent - Day 23

All known living organisms have their genetic information encoded in a molecule called deoxyribonucleic acid or DNA. Genetic information is encoded as a sequence of four nucleotides: guanine (G), adenine (A), thymine (T), and cytosine (C) recorded using the letters G, A, T, and C.  DNA molecules are double-stranded helices that strands run in opposite directions to each other

If we were to extended DNA molecules, they would be very long, however DNA is instead coiled and packaged in structures called chromosomes, which in turn are contained in the nucleus of the cell. Different species have different numbers of chromosomes (humans have 46 chromosomes, or 23 sets of chromosome pairs; peas have 14 chromosomes or 7 pairs; and tomatoes 24 chromosomes or 12 pairs). In sexual reproduction, one chromosome in each pair is contributed by each parent.
Each chromosome has a narrowing point called centromere, which divides the chromosome into two sections, or “arms.” The short arm of the chromosome is labeled the “p arm.” The long arm of the chromosome is labeled the “q arm.” The location of the centromere on each chromosome gives the chromosome its characteristic shape, and can be used to help describe the location of specific genes.

## Element 22: Titanium - Sci-advent - Day 22

Element 22 was named after the Titans - sons of the Earth - in Greek mythology. Titanium was discovered by William Gregor in 1791 in Cornwall, England and it is the ninth most abundant element in the Earth's crust. It is found in minerals such as rutile, ilmenite and sphene. Pure titanium was first produced in 1910 by Matthew A. Hunter.

Titanium is a strong light metal: to get in idea, it is as strong as steel, but 45% lighter. It is resistant to corrosion and does not react with the human body; it is paramagnetic and has a low electrical and thermal conductivity. Due to its characteristics it is used in a number of components that are exposed to sea water. In alloys it is used in airplanes and rockets, and in implants such as artificial hips, pins and other biological implants. Titanium oxide (TiO2) is used as a pigment to create white paint and accounts for the largest use of the element. Titanium tetrachloride (TiCl4), another titanium compound, has been used to make smoke screens. Pure titanium oxide is relatively clear and is used to create titania, an artificial gemstone. Powdered titanium is used in pyrotechnics as a source of bright-burning particles.

## Photoelectric Effect - Sci-advent - Day 21

We have seen how light could be described in terms of a wave, as demonstrated by the double-slit experiment. Nonetheless, that is not the whole story. For instance, in 1888, Wilhelm Hallwachs describes an experiment using a circular zinc plate mounted on an insulating stand and attached by a wire to a gold leaf electroscope, which was then charged negatively. The electroscope lost its charge very slowly. However, if the zinc plate was exposed to ultraviolet light, charge leaked away quickly. The leakage did not occur if the plate was positively charged.

By 1899, J. J.Thomson established that the ultraviolet light caused electrons to be emitted, the same particles found in cathode rays: atoms in the cathode contained electrons, which were shaken and caused to vibrate by the oscillating electric field of the incident radiation. In 1902, Philipp Lenard described how the energy of the emitted photoelectrons varied with the intensity of the light: doubling the light intensity doubled the number of electrons emitted, but did not affect the energies of the emitted electrons. The more powerful oscillating field ejected more electrons, but the maximum individual energy of the ejected electrons was the same as for the weaker field.

In 1905 Einstein gave proposed a way to explain these observations: He assumed that the incoming radiation should be thought of as quanta of frequency hf, with f  the frequency. In photoemission, one such quantum is absorbed by one electron. If the electron is some distance into the material of the cathode, some energy will be lost as it moves towards the surface. There will always be some electrostatic cost as the electron leaves the surface, this is usually called the work function, W. The most energetic electrons emitted will be those very close to the surface, and they will leave the cathode with kinetic energy. This explanation was successful and validates the interpretation of the behaviour of light as particles. In 1921, Einstein was awarded the Nobel Prize in Physics  "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect".

One very prominent application of the photoelectric effect is solar energy produced by photovoltaic cells. These are made of semi-conducting material which produce electricity when exposed to sunlight.

## Sistema Numeral y Calendario Maya

Los Mayas son una de las más grandes civilizaciones humanas. No sólo tienen una excelente agricultura, cerámica y la escritura jeroglífica, pero también tienen obras arquitectónicas impresionantes y arte simbólico, así como matemáticas, astronomía y calendarios. Dicen por ahí que los Mayas predijeron "fin del mundo", pero para mí se trata más bien del fin y el comienzo de un ciclo en el  calendario Maya; no muy distinto de nuestro arbitrario 31 de Diciembre...

Para entender el ciclo del calendario Maya, es necesario saber un poco acerca de su sistema numérico, que es un sistema vigesimal, es decir, sobre la base del número 20. El sistema utiliza tres símbolos numéricos básicos, una concha para el cero, un punto para el 1 y una línea para el  5. También hay que resaltar es que los Mayas fueron una de las primeras civilizaciones en el mundo en desarrollar el concepto del cero. El sistema es pseudo-posicional; en un verdadero sistema vigesimal posicional, el número que aparece primero indica el número de unidades hasta 19, el siguiente número denota el número de 20s hasta 19, el siguiente el número de 400s hasta 19, etc. En el sistema de numeración Maya inicia de esa manera con las unidades hasta 19, seguido de 20s hasta 19, pero cambia en el tercer lugar, el cual denota el número de 360s hasta 19. Después de esto el sistema revierte a múltiplos de 20 por lo que el cuarto lugar es el número de 18 × 202, la siguiente el número de 18 × 203 y así sucesivamente. Por ejemplo [8, 14, 3; 1; 12] representa

12 + 1 × 20 + 3 × 18 × 20 + 14 × 18 × 202 + 8 × 18 × 203 = 1253912.

Otro ejemplo [9; 8; 9; 13; 0] representa

0 + 13 × 20 + 9 × 18 × 20 + 8 × 18 × 202 + 9 × 18 × 203 =1357100.

Ahora bien, veamos el calendario: el calendario  y el sistema numérico están estrechamente relacionados. Los Mayas tenían dos calendarios: Tzolkin de 260 días, con 13 meses de 20 días cada uno, y el Haab de 365 días, con 18 meses de 20 días cada uno y un mes más corto de 5 días (llamado Wayeb). El Tzolkin era un calendario ritual, mientras que el Haab era civil; el Wayeb era considerado de "mala suerte". Con estos dos calendarios, es posible calcular cuando inician un nuevo ciclo: el mínimo común múltiplo de 260 y 365 es 18,980 días, equivalente a 52 años civiles o  73 años rituales. La astronomía también jugó un papel importante, por ejemplo, los astrónomos Mayas calcularon el período sinódico de Venus (después del cual el planeta regresa a la misma posición) siendo éste de 584 días. En dos ciclos de 52 años, Venus habría dado 65 vueltas y volvería a la misma posición.

Aparte de esos calendarios, los Mayas tenían otra forma de medir el tiempo utilizando una base de escala absoluta de una "fecha y hora de creación" la cual a menudo se toma como el 12 de agosto 3113 AC (pero por supuesto que es una cuestión de debate). Esta fecha puede ser tomada como el cero de la llamada "Cuenta Larga". La Cuenta Larga se basa en un conteo de 360 ​​días representados en el sistema de numeración Maya. Vamos a echar un vistazo a un ejemplo: [9, 8, 9, 13, 0] es la fecha de finalización en un edificio en Palenque en Tabasco, México. Esto se traduce en

0 + 13 × 20 + 9 × 18 × 20 + 8 × 18 × 202 + 9 × 18 × 203

que es 1357100 días a partir de la fecha de creación del 12 de agosto 3113 por lo que el edificio fue terminado en el año 603 DC.

La Cuenta Larga se divide de la siguiente manera:

• 1K'in = 1 día
• 1 Winal = 20 K'in
• 1 Tun = 18 Winal = 360 K'in
• 1 K'atun = 20 Tun = 7200 K'in
• 1 Baktun = 20 Kátun = 144,000 K'in

El 21 de diciembre del 2012, el Baktun 14 comienza, teniendo como representación [13,0,0,0,0] y, por supuesto, se termina el Baktun 12 ... ¡pero ciertamente no se acaba el mundo!

## Mayan Numeral System and Calendar - Sci-advent - Day 20

The Mayas are one of greatest human civilisations. Not only did they have excellent agriculture, pottery and hieroglyph writing, but also have some of the most impressive architecture and symbolic art as well as mathematics, astronomy and calendar-making. It is said that they had predicted the "end of the world", but I would like to think of it as the end and beginning of a calendar cycle. Not so different from the arbitrary December 31st in our calendars...

In order to understand the Mayan calendar cycle, we need to know a bit about their number system, which is a vigesimal system, i.e. base on the number 20. They used three basic number symbols, a shell for zero, a dot for 1 and a line for 5.  Also of note is that they were one of the earliest civilizations anywhere in the world to have the concept of zero. The system is pseudo-positional; in a true positional vigesimal system, the number that appears first would denote the number of units up to 19, the next would denote the number of 20s up to 19, the next the number of 400's up to 19, etc. In the Mayan system the numbering starts in that way with the units up to 19 and the 20s up to 19, but it changes in the third place and this denotes the number of 360's up to 19. After this the system reverts to multiples of 20 so the fourth place is the number of 18 × 202, the next the number of 18 × 203 and so on. For example [ 8;14;3;1;12 ] represents

12 + 1 × 20 + 3 × 18 × 20 + 14 × 18 × 202 + 8 × 18 × 203 = 1253912.

As a second example [ 9;8;9;13;0 ] represents

0 + 13 × 20 + 9 × 18 × 20 + 8 × 18 × 202 + 9 × 18 × 203 =1357100.

Now, to the calendar: the calendar was truly behind the number system and vice versa. They had two calendars: Tzolkin with 260 days, with 13 months of 20 days each, and the Haab with 365 days, with 18 months  of 20 days each and a shorter month of 5 days (called Wayeb). The Tzolkin was a ritual calendar, while the Haab was a civil one and the Wayeb was considered "unlucky". With these two calendars, it is possible to see when they would return to the same cycle:  the least common multiple of 260 and 365 is 18980 days; equivalent to 52 civil years or 73 ritual years. Astronomy also played an important role for instance, Mayan astronomers calculated Venus' synodic period (after which it has returned to the same position) to be 584 days. In two 52 year cycles, Venus would have made 65 revolutions and be back to the same position.

A part from those calendars, the Mayas had another way of measuring time using an absolute scale base on a "creation date and time" often taken to be 12 August 3113 BC (but of course that is a matter of debate). This date can be taken as t the zero of the so-called "Long Count". The Long Count is based on a count of 360 days represented in the Mayan number system. Let us have a look at an example: [9; 8; 9; 13; 0] is the completion date on a building in Palenque in Tabasco, Mexico. It translates to

0 + 13 × 20 + 9 × 18 × 20 + 8 × 18 × 202 + 9 × 18 × 203

which is 1357100 days from the creation date of 12 August 3113 BC so the building was completed in 603 AD.

The Long Count was divided as follows:

• 1K'in = 1 Day
• 1 Winal = 20 K'in
• 1 Tun = 18 Winal = 360 K'in
• 1 K'atun = 20 Tun = 7200 K'in
• 1 Baktun = 20 K'atun = 144,000 K'in

On December 21, 2012, the 14th Baktun starts with the representation [13.0.0.0.0] and of course the 13th Baktun finishes... but certainly not the world!

## Double Slit Experiment - Sci-advent - Day 19

The double-slit experiment is one of the most famous experiments in physics and one with great implications in our understanding of Nature. Although the experiment was realised originally with light, it can be done with any other type of wave.

Thomas Young conducted the experiment in the early 1800s. The aim was to allow light to pass through a pair of slits in an opaque screen. Each slit, diffracts the light and thus each acts as an individual light source. When a single slit was open, the light hit a screen with a maximum intensity in the centre and fading away from it. But when there are two slits then the light produces an interference pattern in the screen - a result that would not be expected if light consisted strictly of particles. Although the experiment favours the wave-like description of light, that is not the whole story. This interpretation is at odds with phenomena where light can behave as it is composed of discrete particles, such as the photoelectric effect. Light exhibits properties of both waves and particles, giving rise to the concept of wave-particle duality used in quantum mechanics.

## Total Internal Reflection - Sci-advent - Day 18

We are well acquainted with some optical phenomena such as reflection an refraction; simply take a look at an object half-submerged in a glass of water. But light has other (many other) trick under its sleeve. One very useful trick is total internal reflection. As the name suggests, this phenomenon happens when a ray of light incides in a medium boundary at a very particular angle (known as the critical angle) with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary the light cannot pass through and instead it is all reflected, as if it had hit a perfect mirror.
Total internal reflection is widely used I the operation of optical fibres and devices such as endoscopes and in telecommunications, rain sensors in cars and some multi-touch displays.

## Saturn's Hexagonal Storm - Sci-advent - Day 17

Saturn is well-know by its rings and it cannot be denied that they are a feature that makes of this planet an intriguing world. However, in the 1980s NASA’s Voyager 1 and 2 observed a bizarre, but symmetrically interesting feature in the north pole of Saturn: a hexagonal shaped storm. More recently, NASA's Cassini has been able to image Saturn hexagon in greater detail. The hexagon is 25,000 km (15,000 miles) across. In fact, you could nearly fit four Earth-sized planets there.

The hexagon appears to have remained fixed with Saturn's rotation rate and axis since first glimpsed by Voyager. The actual reason for the pattern in the storm is still a matter of speculation. Kevin Baines, atmospheric expert and member of Cassini's visual and infrared mapping spectrometer team at NASA's Jet Propulsion Laboratory is quoted saying: "Once we understand its dynamical nature, this long-lived, deep-seated polar hexagon may give us a clue to the true rotation rate of the deep atmosphere and perhaps the interior.

## The most secret of messages... cracked!!

In a past post I mentioned the serendipitous discovery of an encrypted message attached to the leg of a pigeon. The message, from WWII, had eluded the experts at GCHQ and the contents of the message were therefore not known. Well, it seems that a Canadian citizen has managed to do the impossible and cracked the code. His name is Gord Young, and he has been quoted saying that it took him 17 minutes to decipher the code. How did he do it? Well, it seems that he was able to do it with the help of a code book inherited.

So what is the content of the most secret of messages? Mr Young says the note uses a simple World War I code to detail German troop positions in Normandy. Here are the alleged contents of the message:

•  AOAKN - Artillery Observer At "K" Sector, Normandy
•  HVPKD - Have Panzers Know Directions
• FNFJW - Final Note [confirming] Found Jerry's Whereabouts
• DJHFP - Determined Jerry's Headquarters Front Posts
• CMPNW - Counter Measures [against] Panzers Not Working
• PABLIZ - Panzer Attack - Blitz
• KLDTS - Know [where] Local Dispatch Station
• 27 / 1526 / 6 - June 27th, 1526 hours

Is this what the message say? Well, GCHQ is surely interested in talking to Mr Young about his work... What do you think?

## Transistor - Sci-advent - Day 16

If is said that if a cell is the building block of life, then a transistor is the building block of the digital era. Without them a lot of the gadgets, gizmos and technology we use today will simply not be there.

Transistors amplify current, for example they can be used to amplify the small output current from a logic integrated circuit to operate a high current device. A transistor can be thought of as a kind of switch used in a variety of circuits; and this is a function that is very important in computers for instance. The fact that the switch can change between on and off makes it possible to implement binary calculations. In today's complex computers there are several thousands, even millions of transistors.

## Laser - Sci-advent - Day 15

Lasers have become so common that the number of applications they have do not surprise us. Nonetheless, their characteristics still captivate all of us. Laser is an acronym of Light Amplification by the Stimulated Emission of Radiation and it is indeed a very descriptive name.

A laser consists of three main elements: a gain medium, an energy source and a device to provide feedback to the system. The amplification of the electromagnetic radiation is done by gain medium. This is possible by pumping energy to the system and thus generating stimulated emission. It is very common for typical lasers to use feedback from an optical cavity, such as a pair of mirrors at each end of the gain medium.

Laser light is characterised by properties such as monochromaticity, coherence and power.

## Positron Emission Tomography - Sci-advent - Day 14

One may think that anti-matter features only in theoretical physics textbooks or in sci-fi devices, nonetheless it is very much in current use. Positrons are the anti-particle of electrons and their existence was proposed theoretically by Paul Dirac in 1928 and they were observed experimentally a year later. Nowadays positrons have a number of applications, including medical imaging.

Positron Emission Tomography (PET) is a three-dimensional imaging technique that works by detecting pairs of gamma rays emitted indirectly by a positron-emitting radionuclide introduced into the body. The radioactive tracer is usually injected into the subject, once inside the body it undergoes positron emission decay and it emits a positron. The positron travels in tissue for a short distance, losing kinetic energy until it is able to interact with an electron. The positron-electron interaction annihilates the pair generating gamma rays which are detected by the scanner.  Finally the images are built with the aid of computers.

## Peltier Effect - Sci-advent - Day 13

The Peltier effect is named after Jean Charles Athanase Peltier who discovered it by accident while investigating electricity. In the eventful experiment, Peltier joined a copper and a bismuth wires together and connected them to each other, then to a battery. When he switched the battery on, one of the junctions of the two wires got hot, while the other junction got cold.

The Peltier effect is the heat exchange that results when electricity is passed across a junction of two conductors, and is a close relative of the Seebeck effect (effectively the same phenomenon in reverse, used in thermocouples used to measure temperature), and the Thomson effect (generation of electricity along a conductor with a temperature gradient). Sparing ourselves the maths, conduction electrons have different energies in different materials, and so when they are forced to move from one conductor to another, they either gain or lose energy. This difference is either released as heat, or absorbed from the surroundings.

When two conductors are arranged in a circuit, they form a heat pump, able to move heat from one junction to the other. Unfortunately, though, it’s not always this simple, as the Peltier effect is always up against the Joule effect – the ‘frictional’ heating that results from electrons bouncing off the atoms. In most systems, this swamps the Peltier effect, and means that all that you get is a bit more heating at one junction, and a bit less heating at the other. Nonetheless, the Peltier effect has a lot of technological potential. It is very reliable, and since it has no moving parts, it rarely needs maintenance while being mobile.

## Magnetism - Sci-advent - Day 12

Materials that respond to the application of a magnetic field are described as magnetic materials. Magnetism can be attractive (paramagnetism) or repulsive (diamagnetism). Some materials are permanent magnets, this mess that their magnetic fields are persistent and they are caused by ferromagnetism.

Magnetic phenomena are closely related to electricity: a magnetic field can be created by moving electric charges. Electromagnetic radiation, such as light, is a form of energy emitted and absorbed by charged particles. It can exhibit a wave-like behaviour as it propagated through space.

It is possible to map the magnetic field of an object by measuring the strength and direction of the field at various locations. By following the arrows drawn you end up with field lines for the field. A map of this sort can be visualised, for instance, by doing a very simple experiment involving a magnet bar and some iron filings (see image above).

## Periodic Table (by abundance) - Sci-advent - Day 11

A 1970 periodic table by Prof. Wm. F. Sheehan of the University of Santa Clara that claims to show the elements according to relative abundance at the Earth's surface.

Dmitri Mendeleev published a first version of the periodic table in 1869. The table was developed to illustrate periodic trends in the properties of the then-known elements, which are presented in order of increasing atomic number. This allowed Mendeleev to predict some properties of elements that were unknown at the time.

Mendeleev's periodic table has since been expanded and refined with the discovery or synthesis of further new elements.

## Zombie Spiders - Sci-advent - Day 10

Spiders and their webs are an excellent example of a predator, but can you enslave a spider? Well it seems that a species of wasp has mastered the art. The unsuspected spider is instructed by the parasite to leave its web behind and start building a new one with a very different architecture that will serve as a nest to nurse the larva of the wasp. The new web has a thick cover and a lower platform where a cocoon hangs. The cover protects the cocoon from rain for instance. Once the wasp hatches it then has the zombie spider as a first meal...

Ada Lovelace. Painting by Margaret Sarah Carpenter (1793–1872)

Ada Augusta Byron, Countess of Lovelace, was the daughter of the poet George Gordon, Lord Byron. She studied mathematics at the University of London with Charles Babbage, whose analytical engines were the precursors of the modern computer. Today 10th of December, it would have been her 197th birthday. That is why Google created a doodle for her (see image below).

Ada Lovelace is today known as a mathematician and computer pioneer; she created the concept of an operating system. Supplementing her translation of an Italian article on Babbage's analytical engine with an encoded algorithm she published the first computer program, albeit for a machine that would not be built until more than 150 years later as a historical project.

The Ada computer language was named after her.

## Sir Patrick Moore - Sci-advent - Day 8

British astronomer and broadcaster Sir Patrick Moore, died aged 89

Sir Patrick Moore was an inspiration to generations of astronomers and scientists in general. He presented the BBC programme The Sky At Night for over 50 years, making him the longest-running host of the same television show ever. The first programme was on April 24th, 1957. Sir Patrick's last appearance was last Monday, December 3rd, 2012.
He wrote dozens of books on astronomy and his research was used by the US and the Russians in their space programmes.

## Total Solar Eclipse - Sci-advent - Day 7

Total solar eclipse over the Marshall Islands in 2009. Picture by Vojtech Rusin.

A solar eclipse happens when, as seen from the Earth, the Moon passes in front of the Sun and thus blocking it either fully or partially. This can happen only at new moon, when the Sun and the Moon are in conjunction as seen from Earth.

Grrrreat!

## Mathematical Theorems - Sci-advent - Day 6

Mathematical theorem network built from Walter Rudin's Principles of Mathematical Analysis.

Scientific knowledge is built by building up on hypotheses and theories, repeatedly check them against observations of the natural world and continue to refine those explanations based on new ideas and observations. In the case of mathematics, that knowledge is organised in an incredibly structured manner. Starting up with properties of natural numbers, called axioms, and slowly working our way up, reaching the real numbers, calculus, and... well beyond. To prove new theorems, mathematicians make use of old theorems, creating a network of interconnected results—a mathematical house of cards.

Andy Reagan has recently published a blog post entitled "What's the most important theorem?" where following Walter Rudin’s Principles of Mathematical Analysis, he displays them as nodes in a network.

The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator. It was built by the European Organization for Nuclear Research (CERN). It has become a prominent facility due to the work that is being carried there to prove or disprove the existence of the Higgs boson and of the large family of new particles predicted by supersymmetric theories.

The LHC was built in collaboration with over 10,000 scientists and engineers from over 100 countries, as well as hundreds of universities and laboratories. It lies in a tunnel 27 kilometres in circumference, as deep as 175 metres (574 ft) beneath the Franco-Swiss border near Geneva, Switzerland.

## The Cave of Crystals – Sci-Advent – Day 4

A thousand feet (304 meter) underground, the Cave of Crystals (pictures) is just one of a series of glittering caverns beneath the Desert in the Mexican state of Chihuahua near Naica (map). Much of the complex would naturally be filled with scorching water, were it not for industrial pumps that facilitate the mining of silver, zinc, lead, and other minerals in the caves.

The temperature in the cave is about 50C, and it's the virtually 100% humidity. When the cave was first discovered it was just an accident. Miners working in the Naica silver mine broke through the walls of the cavern and were astounded to discover these enormous crystals - the biggest anywhere on Earth.

## The Babbage Difference Engine - Sci-Advent - Day 3

In 1849, British inventor Charles Babbage completed designs for a difference engine, a very early mechanical computer. Due to cost and complexity the machine was never built in his lifetime and for 150 years nobody knew if the machine would have worked. In 2002, a Babbage Difference Engine based on the original plans was completed—and it actually works. The hand-cranked device has 8,000 parts, weighs 5 tons, and is 11 feet long. Two such machines now exist, one at the Science Museum in London and another at the Computer History Museum in Mountain View, California. To get a sense of the incredible intricacy of the Babbage Difference Engine, take a look at these interactive high resolution images of the Computer History Museum machine. The images, created by xRez Studio, are each composites of up to 1,350 individual photos. The studio also shot this short video of the machine in operation.

## Skylon - Sci-advent - Day 2

The image shows the flow of hot air passing through the piping in a cooler for a new engine that is able to lower the temperature of the air lower than -140C in just 1/100th of a second.

The cooler is part of a new type of spaceplane engine demonstrated bye Reaction Engines Ltd (REL), Oxfordshire. The company ran a series of tests on key elements of its Sabre propulsion system under the independent eye of the European Space Agency (Esa).

REL's idea is for an 84m-long vehicle called Skylon that would do the job of a big rocket but operate like an airliner, taking off and landing at a conventional runway. The vehicle would burn a mixture of hydrogen and oxygen but in the low atmosphere the oxygen would be taken from the air, in the same way that a jet engine breathes air.

Taking its oxygen from the air in the initial flight phase would mean Skylon could fly lighter from the outset with a higher thrust-to-weight ratio, enabling it to make a single leap to orbit, rather than using and dumping propellant stages on the ascent - as is the case with current expendable rockets. A key element is the engine's ability to manage the hot air entering its intakes at a high speed. These gases have to be cooled prior to being compressed and burnt with the onboard hydrogen.

REL's solution is a module containing arrays of extremely fine piping that can extract the heat and plunge the inrushing air to about -140C in just 1/100th of a second. Ordinarily, the moisture in the air would be expected to freeze out rapidly, covering the piping in a blanket of frost and dislocating their operation.

It is the innovative helium cooling loop with its pre-cooler heat-exchanger that REL has been validating on an experimental rig.

## Rocknest - Sci-advent - Day 1

In the tradition of Advent Calendars, I will be posting some science related entries from today up until Dec 24th... So, here's the first entry:

Panoramic View From 'Rocknest' Position of Curiosity Mars Rover
This panorama is a mosaic of images taken by the Mast Camera (Mastcam) on the NASA Mars rover Curiosity while the rover was working at a site called "Rocknest" in October and November 2012.

The center of the scene, looking eastward from Rocknest, includes the Point Lake area. After the component images for this scene were taken, Curiosity drove 83 feet (25.3 meters) on Nov. 18 from Rocknest to Point Lake. From Point Lake, the Mastcam is taking images for another detailed panoramic view of the area further east to help researchers identify candidate targets for the rover's first drilling into a rock.

The image has been white-balanced to show what the rocks and soils in it would look like if they were on Earth. The raw-color version, shows what the scene looks like on Mars to the camera.

Image Credit: NASAx/JPL-Caltech/Malin Space Science Systems

## Working with logarithms base 10, 2 and e...

A couple of weeks ago I was talking about logarithms and their use. They may seem to be a bit esoteric and they can cause a bit of head-scratching: a logarithm (base $latex a$) of a number $latex b$ is denoted by $latex log_a b$ and can be better understood in terms of an exponential function since the result is the power to which the base has to be raised to produce the number, i.e. $latex log_a b=x \leftrightarrow a^x=b$.

Nonetheless, using the base $latex e$ for logarithms is far more natural and as a form of abbreviation, it is denoted by $latex ln$. In spite of this, a lot of us still learn about this function with the base 10 (or simply $latex log$). Furthermore, the importance of the binary system makes it very useful to know about $latex log_2$. With that in mind, I ended up mentioning an approximation in which all three logarithms appear:

$latex log_2 (x)\simeq ln (x) + log (x)$

This can be very handy as you can approximate the value of the logarithm base 2 with a pedestrian calculator... of course you can still do this using the functions that some calculators offer you, but that is not the point of this post...

Anyway, note that it is an approximation and as such we could ask what is the relative error obtained when using it. Well, let us have a look: if the above expression holds, we can divide both sides by $latex log_2 (x)$ to obtain:

$latex 1\simeq \frac{ln (x) + log (x)}{log_2 (x)}$.

So the relative error can be expressed as:

$latex \epsilon_r = 1 - \frac{ln (x) + log (x)}{log_2 (x)}$.

That is all fine and good, but what is the value of that error? Well, let us use some of the properties of logarithms. We know that $latex log_a b=x \leftrightarrow a^x=b$. Also, it is true that $latex a^x=e^{x ln(a)}$, and thus we can say that $latex e^{x ln(a)}=b$.  From this it follows that $latex ln(b) = x ln(a)$. Nonetheless, we know that $latex x=log_a b$. Rearranging the terms we end up with the fact that:

$latex log_a b = \frac{ln b}{ln a}$.

Using that expression we can re-write the relative error as follows:

$latex epsilon_r = 1 - \frac{ln (x) + \frac{ln(x)}{ln(10)}}{\frac{ln (x)}{ln (2)}}=1-(ln 2)left(1+\frac{1}{ln 10} right)\simeq 0.00582282...$

Not too big an error! Let us have a look, $latex log_2 (10)=ln 10 +1\simeq 3.30259...$, whereas the actual value is closer to $latex log_2 (10)=3.32193...$

Interesting, don't you think...

## The most secret of messages...

David Martin, a retired British civil servant was cleaning the chimney of his house in Bletchingley (Surrey), 35 miles south of London, when he found the remains of a pigeon. But this was not any pigeon: it was a carrier pigeon, and its leg still had attached to it a red metallic container with an encrypted message inside. Experts from the UK Government Communications Headquarters (GCHQ) have recently given up and recognised that it is almost impossible to find out the content of that message.

They know it is a message of World War II, that the addressee was X02, code name of the Bomber Command and believe that the pigeon could have started its flight around the time of the Normandy landings. They also know that it was heading to Bletchley Park, the communications centre during the war, some 100 km north of London.

They also know other things. They know that the sender's signature, Searjeant W Stot, suggests that it was a message from the RAF. The spelling of the word "Serjeant" is crucial as the RAF used letter "j" instead of "g".

However, they have failed to know the meaning of the message. They have no idea of the way to decipher the meaning of the 24 blocks of five letters each, and which to the eyes of the layman and the expert alike are nothing more than an alphabet soup of seemingly meaningless strings of letters: Take a lok at the first line of the message: AOAKN HVPKD FNFJW YIDDC.

These types of code were used in operations such that the messages could only be read by the people who sent them and the rightful recipients.

GCHQ have said that there are two possibilities. If the code was based on a codebook designed specifically for a single operation or mission, "it is unlikely" that someday it can be deciphered. If it was used only once and the encryption is truly random, and the key was just kept by the person who sent the message and the person who would receive it, then it quite likely that the message is indecipherable.

The code is impenetrable to the current government experts and it has been suggested that the only way to gain some insight is a collaboration with experts active at the time the message was sent, i.e. the people who were at Bletchley Park during the war and are now around 90 years old.

The British Army trained 250,000 carrier pigeons to be used in their secret communications during the war. They were particularly useful during the Normandy landings because Churchill had imposed a blockade of radio communications to increase safety and avoid providing clues to the Germans. The pigeons could fly at speeds greater than 125 kilometres per hour and cover distances of over 1,500 kilometres.

Percy, as this particular pigeon has been named, was probably disoriented and lost due to bad weather or simply exhausted after crossing the English channel. Carrier pigeon enthusiasts have proposed that the government posthumously grant Percy the Dickin Medal, the highest award given to animals for their courage.

Can you help crack the code?

The pigeon message is as follows:

AOAKN HVPKD FNFJW YIDDC
RQXSR DJHFP GOVFN MIAPX
PABUZ WYYNP CMPNW HJRZH
NLXKG MEMKK ONOIB AKEEQ
WAOTA RBQRH DJOFM TPZEH
LKXGH RGGHT JRZCQ FNKTQ
KLDTS FQIRW AOAKN 27 1525/6

## iBooks Author supports LaTeX now

When Apple launched iBooks Author back in January 2012 I was quite curious to see the things that you were able to do with it. It all looked very nice and relatively easy to use. You can create documents using some templates provided and you then are able to export them as PDF or even publish them as iBooks.

Unfortunately, at the time, Apple failed to put any easy support to include equations or mathematical symbols. That alone put me off using the application altogether (see post). However, in the recent update (released on October 23rd) Apple has finally included an equation editor that uses LaTeX or  MathML. I have just tried it and it seems to do a good work. Definitely not as powerful as the actual LaTeX engine (it does not let you number the equations automatically for instance), but it is an improvement.

Here are some screenshots of the little first trial I did. As you can see the update clearly states that the new editor accepts native LaTeX or MathML:

Now, to insert a new equation:

This opens up the equation editor:

In the new window you can start typing your LaTeX commands. Notice that you don't need to start an equation environment as you would do in LaTeX, you simply type the commands that will create the maths:

Once you have done that, simply tell iBooks Author to insert the equation, and voilà:

Have you used iBooks Author? What do you think of it? What is your opinion about the support for LaTeX?

I think I may give it a go, but will probably continue using LaTeX itself. If you want to learn learn about using it have a look at these past posts:

## Muchas gracias por sus enseñanzas Dr Leopoldo García-Colín Scherer. Todo un honor haber sido su estudiante.

Muchas gracias por sus enseñanzas Dr Leopoldo García-Colín Scherer. Todo un honor haber sido su estudiante.

## Un universo sin centro...

Finalmente un poco de tiempo para escribir algo para el blog, y en esta ocasión una gran oportunidad para contestar una pregunta que a inicio de la semana Jorge Soto, si de Moenia, me envió. En verdad un acontecimiento que en sí mismo merece una entrada en el blog, pero mejor aún cuando me da la oportunidad de escribir acerca de algo interesante. ¡Gracias Jorge!
La pregunta decía algo así como "después del Big Bang, ¿en qué lugares es más posible que haya vida, cerca o lejos del centro?".
Al recibir la pregunta, le comenté a Jorge que la respuesta rápida sería que en principio es igualmente probable, pero que lo más interesante (para mí, al menos) en la pregunta es el hecho de que el universo no tiene centro...

De acuerdo con las las teorías estándar de la cosmología, el universo comenzó con un "Big Bang" cerca de 14 mil millones de años y se ha ido expandiendo desde entonces. Sin embargo, no existe un centro para la expansión, ya que es la misma en todas partes. El inicio se da en una singularidad, pero es importante remarcar que una singularidad no es una cosa tangible, no es un punto. Uno no puede señalar y decir "Mira, qué cosa, una singularidad". El Big Bang no es algo que ocurrió en un lugar determinado y como tal no no debe ser visto como una explosión ordinaria. El universo no se expande hacia fuera desde un centro hacia el espacio, sino que todo el universo está en expansión, por lo cual podemos decir que está haciendo lo mismo en todos lados. O tal vez, visto de otra manera, el centro está en todos lados.
En 1929 Edwin Hubble anunció que de acuerdo a sus mediciones de la velocidad de las galaxias a distintas distancias de nosotros, entre más lajanas se encuentran dichas galaxias, más rápido se alejan. Esto podría sugerir que nos encontramos en el centro del universo en expansión, pero de hecho, si el universo se expande uniformemente de acuerdo con la ley de Hubble, entonces aparecerá hacerlo desde cualquier punto de vista.
Si una noche de observación vemos una galaxia, llamémosla A, que se aleja de nosotros a 10,000 km/s, un alien de dicha galaxia verá a la Vía Láctea alejarse a la misma velocidad de 10,000 km/s en la dirección opuesta. Otra galaxia B, dos veces más lejos en la misma dirección que A, será vista por nosotros con un alejamiento a 20,000 km/s. El alien de la galaxia A marcará un alejamiento a 10,000 km/s para la galaxia B. En otras palabras, desde el punto de vista del alien en B, todo se expande fuera desde donde el/ella/eso se encuentra, de igual manera que sucede para nosotros aquí en la Tierra.
Una analogía que ha sido usada por científicos prominentes como Arthur Eddington o Fred Hoyle es la de un balón en expansión. En su libro de 1960 "La naturaleza del universo", Hoyle escribe: "Mis amigos que no son matemáticos a menudo me dicen que les resulta difícil imaginar a esta expansión. Sin acudir a una gran cantidad de matemáticas, lo mejor que puedo hacer es utilizar la analogía de un globo con un gran número de puntos marcados en su superficie. Si el globo se infla, las distancias entre los puntos aumentan en la misma forma que las distancias entre las galaxias".
Esta es una buena analogía, pero debe ser entendida apropiadamente. de lo contrario puede causar más confusión. Como el mismo Hoyle dijo: "Hay varios aspectos importantes en los que es definitivamente engañosa". Es importante tener en cuenta el espacio tridimensional que observamos en el universo, comparado con la superficie bidimensional del globo. La superficie es homogénea, sin ningún punto pueda ser elegido como el centro. El centro del globo en sí no está en la superficie, y por tanto no debe ser considerado como el centro del universo. Si resulta de  ayuda, podemos pensar en la dirección radial en el globo como el tiempo. Sin embargo es mejor no considerar en absoluto los puntos fuera de la superficie del globo como parte del universo. Por lo tanto el espacio puede ser curvo sin haber otras dimensiones fuera de éste. Al considerar esta analogía hay varias cosas que recordar:
1.  La superficie bidimensional del globo es análogo a las 3 dimensiones del espacio.
2. El espacio tridimensional en la que está incrustado el globo no es análogo a ningún espacio físico con dimensiones superiores.
3. El centro del balón no corresponde con nada físico.
4. El universo puede ser finito en tamaño y puede estar en crecimiento como la superficie de un balón en expansión, pero también podría ser infinito.
5. Las galaxias se alejan como puntos en globo en expansión, pero las propias galaxias no se expanden debido a que están unidas por la gravedad.

Si pensáramos en el Big Bang como una explosión como cualquier otra, con un punto central, dicho centro sería el punto más caliente, con una esfera de material expandiéndose fuera del centro. Sin embargo, hasta donde entendemos, el Big Bang no fue una explosión como tal; fue más bien una explosión del espacio mismo, mas no en el espacio. Si el Big Bang fuese una explosión ordinaria en un espacio existente, sería posible observar el borde de la expansión con espacio vacío más allá. En cambio, cuando observamos vemos hacia el Big Bang mismo y detectamos un débil resplandor de fondo de los gases calientes primordiales del universo temprano. Esta "radiación del fondo cósmico de microondas" es uniforme en todas direcciones. Esto nos indica que no es materia la que se expande hacia el exterior desde un punto, sino que es el propio espacio el que se expande de manera uniforme. Y eso es profundo en sí mismo.
Es importante destacar que otras observaciones apoyan la idea de que no hay centro del universo, al menos en la medida en que las observaciones pueden alcanzar. El hecho de que el universo se expande uniformemente no descartaría la posibilidad de que haya un lugar más denso y caliente que pueda llamarse "el centro", sin embargo estudios cuidadosos de la distribución y el movimiento de las galaxias confirman que es homogéneo a las grandes escalas que podamos observar, y no hay indicios de un punto especial que podamos llamar centro.
La idea de que el universo debe ser uniforme (homogéneo e isotrópico) a escalas muy grandes se conoce como el "principio cosmológico", nombre propuesto por Arthur Milne en 1933. A pesar del descubrimiento de una rica estructura en la distribución de las galaxias, la mayoría de los cosmólogos todavía apoyan el principio cosmológico, ya sea por razones filosóficas o porque es una hipótesis bastante útil que ninguna observación ha contradicho. Sin embargo, nuestra visión del universo está limitada por la velocidad de la luz y el tiempo finito desde el Big Bang. La parte que podemos observar es muy grande, pero es probablemente muy pequeña en comparación con todo el universo. No tenemos forma de saber cuál es la forma del universo más allá del horizonte visible, y no hay manera de saber si el principio cosmológico tiene alguna validez a escalas de distancia mayores.
Una vez entendido eso, es fácil ver por que la probabilidad de la existencia de vida es igual en cualquier parte del universo.

## The Shuttle Enterprise

While visiting the city that never sleeps I finally had the chance to visit the Intrepid Sea, Air and Space Museum in New York. The main attraction for me was the prospect of seeing and being close to the Enterprise shuttle, and having a look at the Concorde.

The museum is quite big and there are plenty of things to see. The shuttle pavilion is at the very end of the aircraft carrier Enterprise and the whole visit was very exciting. The shuttle is housed in a temporary venue and I look forward to seeing the actual permanent building when it is finished. I was surprised to know the story behind the name of this shuttle itself. It seemed to be a bit of a coincidence to share its name with the famous Star Trek spaceship.

The original name was supposed to be Constitution, in honour of the USA's bicentennial. But more than 400,000 trekkies had something else in mind. The petitioned US President Gerald Ford to change the name to Enterprise after the starship captained by James T Kirk. The pavilion shows a picture taken on September 17th 1976 on the day of the shuttle Enterprise roll-out ceremony with some of the Star Trek cast members along with its creator Gene Roddenberry.

## Martian Unconformity

A few posts ago I wrote about the Great Uncomformity, and I was quite interested when I got to hear about Curiosity, the rover, photographing unconformities on Mars. As I explained in the aforementioned post, and unconformity is effectively a discontinuity in the layers of sedimentary rock or strata.

The Mars rover took a picture with its 100mm telephoto and it turned out that the subject of this landscape was a geological unconformity. The picture shows sediments that seem to have been deposited at a different angle from those below them. This we have seen before on Earth deposits where the phenomenon is due to wither volcanic or tectonic activity. Images taken from orbit suggested that the lower part consisted of sediments rich in so-called hydrated minerals, i.e. formed in the presence of water (yes, that is right, water!), but the layers above lacked the minerals. At this stage we will have to wait for further investigations to take place in order to get further evidence that the two layers were laid in different environments.

## Planetary system with two suns

If you have seen Star Wars Episode IV, you probably remember that famous scene when Luke considers his options after Uncle Owen and Aunt Beru are found dead. Atmospheric music by John Williams plays in the background and at the distance we see two suns over the horizon of the planet Tatooine.

But that is certainly not the only appearance of a double-star system with planets in science fiction. What about Gallifrey, the home planet of the Time Lord, Dr Who; or Magrathea, the luxury-planet factory in Hitchhikers' Guide to the Galaxy? Indeed interesting, but not as interesting as the prospect of a real pair of stars with their own planetary system, right? Well, recently scientists have reported the discovery of two planets orbiting a binary system as spotted by the Kepler space telescope.

So, how do we call this system? Well, it has the inspired name of Kepler-47, and it is located in the constellation of Cygnus some 5,000 light-years away. One of the plants is said to be slightly larger than Uranus and has the name of Kepler-47c, while the other one is about a third of the size of our own Earth and its name is Kepler-47b. As for the stars, one is very Sun-like and the other about a third of its partner.

Kepler-47b, the inner planet, is particularly interesting as it is in the habitable zone (or Goldilocks zone) of the system, in other words, it is located in the region where it is neither too cold nor too hot for liquid water to exist on the surface of the planet and thus the possibility of life in the planet is higher. Whether that is Time Lords, planet-making factory workers or rebels, it certainly is not known...

## Neil Armstrong

Neil Armstrong will always be remembered as the first man to walk on the moon. He has died on Saturday 25th of August, weeks after heart surgery and days after his 82nd birthday.

Neil A. Armstrong, was born in Wapakoneta, Ohio, on August 5, 1930. He served as a naval aviator between 1949 and 1952. In 1955 he joined the National Advisory Committee for Aeronautics (NACA) a predecessor of the National Aeronautics and Space Administration agency (NASA).

Armstrong gained his status as an astronaut in 1962. He then was assigned as command pilot for the Gemini 8 mission. Gemini 8 was launched on March 16, 1966, and Armstrong performed the first successful docking of two vehicles in space.

As spacecraft commander for Apollo 11, the first manned lunar landing mission, Armstrong became the first man to land on the moon and the first to step on its surface.

He was Professor of Aerospace Engineering at the University of Cincinnati between 1971-1979. During the years 1982-1992, Armstrong was chairman of Computing Technologies for Aviation, Inc., Charlottesville, Va.

In an address to America’s National Press Club in 2000, Armstrong offered the following self-portrait: “I am, and ever will be, a white-socks, pocket-protector, nerdy engineer, born under the second law of thermodynamics, steeped in steam tables, in love with free-body diagrams, transformed by Laplace and propelled by compressible flow.”

## Y ¿Qué es el Bosón de Higgs?

Uno de los sueños más ambiciosos de los físicos es la descripción de todas las fuerzas físicas como un único conjunto de relaciones matemáticas, lo que se conoce comúnmente como unificación. Todos los fenómenos observados están descrito por 5 fuerzas: la gravedad, el magnetismo, la electricidad, la fuerza nuclear débil y la fuerza nuclear fuerte.

La unificación ha ocurrido en algunos casos, por ejemplo, en la década de 1860 James Clerk Maxwell demostró que el magnetismo y la electricidad son descritos por un único conjunto de ecuaciones. De ahí que se hable de cuatro fuerzas al haber logrado la unificación de la electricidad y el magnetismo en algo que se llama electromagnetismo (muy imaginativos...). Algo similar ocurrió en los años 70s cuando Abdus Salam, Sheldon Glashow y Steven Weinberg unificaron de la fuerza nuclear débil y el electromagnetismo.

Uno puede preguntarse cómo se transmiten las fuerzas y la respuesta actual de la física dice que no se transmiten directamente entre los objetos, más bien las fuerzas son descritas por intermediarios que los físicos llaman campos. Seguramente han oído hablar de el campo eléctrico y el campo magnético, ¿verdad?

En otras palabras, todas las fuerzas de la naturaleza están mediadas por campos que resultan del intercambio de partículas que el Modelo Estándar llama bosones "gauge". Por ejemplo, en el caso de la fuerza electromagnética, la interacción de partículas cargadas eléctricamente sucede gracias al fotón que es la partícula de intercambio de la fuerza electromagnética. Del mismo modo, la fuerza nuclear débil - una interacción repulsiva de corto alcance responsable por algunas formas de radiactividad - se rige por los bosones W y Z.

El corto alcance de la fuerza nuclear débil, y por tanto su debilidad, se produce porque los bosones W y Z son partículas muy masivas, a diferencia de los fotones sin masa. En 1983, los científicos en el CERN descubrieron los bosones W y Z y por lo tanto la llamada teoría electro-débil ha sido verificada convincentemente. Sin embargo, el origen de sus masas sigue siendo un misterio. La mejor explicación en este momento es el mecanismo de Higgs.

La teoría muestra una simetría entre el fotón, W y Z, sin embargo, esta simetría se rompe espontáneamente y se cree que esta separación es la responsable de la masa de los bosones W y Z. Se cree que hay un campo, llamado campo de Higgs, que es responsable de la génesis de la masa. Este campo lleva el nombre del físico escocés Peter Higgs. Ahora, hemos mencionado que cada campo tiene una partícula asociada, en el caso del campo de Higgs tenemos el bosón de Higgs. El bosón de Higgs es la única partícula, en el Modelo Estándar, que no se ha observado (o tal vez si, como se verá más adelante). Su existencia podría explicar cómo la mayoría de las partículas elementales conocidas adquieren masa, y podría explicar la diferencia entre el fotón sin masa y la bosones masivos W y Z. Con ayuda del Gran Colisionador de Hadrones se espera obtener evidencia experimental de la existencia (o no) de esta partícula.

El 4 de Julio pasado el CERN convocó a una conferencia de prensa para un anuncio importante. Resulta que se ha informado acerca del posible descubrimiento de una nueva partícula "consistente" con el bosón de Higgs. Ha sido una búsqueda de 45 años para tener una explicación de cómo la materia adquiere masa. Y la búsqueda aún no ha terminado con este anuncio: se necesita más trabajo para tener la certeza de que verdaderamente éste es el bosón de Higgs.

Peter Higgs, estuvo presente en la audiencia en el teatro de conferencias del CERN, en Ginebra, quien se apresuró a felicitar al equipo por sus logros. El bosón, como hemos mencionado, lleva su nombre y esto fue realmente un acontecimiento trascendental para él.

El equipo del CMS , en el Gran Colisionador de Hadrones (LHC por sus siglas en inglés) , informó que han visto una señal en los datos que correspondería a una partícula con un peso de 125.3 GeV, que es aproximadamente 133 veces más pesada que el protón. Si realmente se confirma, será uno de los mayores descubrimientos científicos en mi vida, pero aún más emocionante es el hecho de que esto no cierra el capítulo, puede incluso abrir otras vías de investigación y entendimiento. Y como tal, los físicos del CERN dicen que actualmente los datos que tienen son compatibles con el de bosón de Higgs del Modelo Estándar...

Related Articles

## The Higgs Boson Explained...with a Cartoon

Here you go! Enjoy!

http://vimeo.com/41038445

http://youtu.be/0hn0jYjijNs

## CERN announces a Higgs-like boson particle

CERN has called for a press conference today (July 4th) for an important announcement. It turns out that they are reporting the claim of the discovery of a new particle "consistent" with the Higgs boson. It has been a search of 45 years for an explanation of how matter acquires mass. And the search is not yet over with this announcement: more work is needed to be certain that this is indeed the Higgs boson.

Peter Higgs was present in the audience in the conference theatre at CERN, Geneva. He was prompt to congratulate the team for their achievement. The famous boson is named after him and this was really a momentous event for him.

The CMS team, at the Large Hadron Collider (LHC), report that they have seen a signature in the data for a particle weighing 125.3 GeV, which is about 133 times heavier than the proton. If actually confirmed, this will be one of the biggest scientific discoveries in my lifetime, but even more exciting is the fact that this does not close the chapter, it may even open other avenues of research and understanding. And as such, the physicists at CERN say that, currently, the data they have is compatible with the Standard Model Higgs boson...

Parece ser que pocos estudiantes de doctorado exploran nuevas tecnologías en sus investigaciones o entienden la variedad de información disponible para ellos, de acuerdo a un reporte encargado por la British Library y JISC (un cuerpo para la tecnología en la educación superior en el Reino Unido). El reporte puede ser visto aqui (en inglés).

"Los investigadores del mañana" publicado el 28 de junio, encuestó a más de 17,000 estudiantes de doctorado (en el Reino Unido) en un período de tres años, siguientdo 60 a profundidad y en particular a los nacidos entre 1982 y 1994, la llamada Generación Y.

El reporte afirma que a pesar de ser conocedores de la tecnología, la Generación Y de estudiantes de doctorado saben muy poco sobre la variedad y la autenticidad de la información de investigación disponible en nuevos formatos, como bases de datos en línea, revistas electrónicas y depósitos, y pocos saben cómo acceder a esta información.

También tienen poca comprensión acerca del tema de acceso abierto y los derechos de autor. Muchos creen que los supervisores no aprobarían el citar documentos acceso abierto o libre y sólo el 26 por ciento saben que los donantes y fundaciones están empezando a esperar el acceso abierto a la investigación que apoyan.

Julie Carpenter, una de las co-autoras del reporte y directora de la consultora Education for Change afirma que los resultados sugieren un descuido hacia los estudiantes de doctorado, los cuales han experimentado una sensación de aislamiento.

Apoyo institucional - en términos de oferta de bibliotecas, información sobre el entorno de la investigación y de formación - no está funcionando y tiene que haber un "cambio de paradigma" en la forma en que el sector da ayuda y se compromete con los estudiantes de doctorado, dijo.

"Hay una desconexión entre las organizaciones estratégicas como JISC, [que] se han empeñado en decir que se deben utilizar estas herramientas maravillosas, promover el intercambio y mover a la investigación a la era electrónica dentro de las propias instituciones", agregó Carpenter.

La aversión al riesgo

Esto se refleja en otro de los hallazgos del estudio: que aunque los estudiantes de la Generación Y utilizan algunas herramientas en línea tales como marcadores (bookmarks) y RSS, muy pocos emplean tecnologías de colaboración como los wikis, los blogs y Twitter en sus investigaciones, a pesar de utilizar estas herramientas en su vida personal.

Debbie McVitty, representante de investigación y políticas para postgraduados en la National Union of Students (Reino Unido) y miembro del grupo asesor de estudios, atribuye en parte la aversión al riesgo a la presión sobre los estudiantes de doctorado para completar sus estudios en lugar de crear una buena investigación.

"La gente que va a adoptar [tecnologías] tempranamente son probablemente las personas, tales como profesores, que están más establecidas en su posición y pueden permitirse el lujo de ser más experimentales", dijo.

"El acceso a un trabajo académico puede ser un tanto difícil - y por tanto no se quiere correr ningún riesgo."

Junto a personal de biblioteca y administradores de universidades, los supervisores tienen que desempeñar un mejor papel en informar a los estudiantes, con apoyo de la medida de sus campos de estudio, e dijo McVitty.

El informe también encontró una "dependencia sorprendente" por los estudiantes de doctorado en las conclusiones de otras personas en lugar de las fuentes originales.

Según la encuesta, en cuatro de cada cinco casos, los estudiantes de doctorado busca los libros y documentos publicados durante su búsqueda de información para apoyar su investigación, en lugar de material "primario" como muestras, archivos y bases de datos.

Los estudiantes también deben recopilar datos y hacer investigación original además de explorar esas fuentes secundarias, comentó Carpenter, pero este hallazgo puede identificar una tendencia que, si se verifica, tendría "consecuencias muy graves".

## Happy birthday Turing

Today, a 100 years ago Alan Turing was born. As a form of celebration Google has put a functioning Turing machine as their latest doodle. A Turing machine is a device that uses a tape with symbols that are manipulated according to certain rules and as you can imagine it was proposed by Turing in 1936.

## Pleasant surprise...

Pleasant surprise to see the poster of the talk at Escuela Superior de Física y Matemáticas (ESFM), IPN Mexico.

## Repulsive Polarons

Yes, indeed this post is about repulsive polarons, but that does not mean that they are repulsive because they cause revulsion or anything of the sort. We are talking about quasiparticles which are predicted to occur when 'impurity' fermionic particles interact repulsively with a fermionic environment. And it turns out that these quasiparticles have now been detected.

Ok, "what is a quasiparticle?" I hear you say. Well, a quasiparticleis a perturbation or disturbance in a medium, whose behaviour is that of a particle and thus for all intent and purposes can be regarded as one. Their study is important in relationship to solid-state physics, condenses matter and nuclear physics as they help us in determining the properties of matter.

Rudolf Grimm (Innsbruck) and a team of physicists have experimentally realised the observation of a repulsive polaron in an ultracold quantum gas. The results have been publised in Nature.

Varios phenomena from condensed matter physics can be experimentally simulated using ultracold quantum gases. In these system, the control that can be achieved over the many-body interactions is grater and this is always helpful.

In order to observe repulsive polarons the physicists used an ultracold quantum gas of lithium and potassium atoms and they control the atomic interactions using electromagnetic fields and RF pulses. The potassium atoms are dirven into a state where they repulse the surrounding lithium atoms. This interaction can be seen as a particle with modified properties - a quasiparticel. Once the researchers analyse the energy spectrum of the system, they were able to demonstrate repulsive polarons.

The observation of these polarons is important as it demonstrates that they can indeed be observed. In condensed matter quasiparticles decay very quickly and this poses the problemof studying them. In this experiments, the researchers say, the polarons showed an almost ten times increased lifetime compared to earlier experiments in similar systems. This opens up the possibility of having a platform for a more detailed analysis of many-body systems that rely on repulsive interactions.

## The Great Unconformity

You might think that this is related to someone sitting in the most uncomfortable position ever, or about a very awkward moment and you would be completely wrong. You would have to pay attention to the fact that there is an "n" and not an "m" in there...

The first time I heard about the Great Unconformity was a few days back in the Nature podcast. An unconformity in this context refers to the contact surface between younger and older rocks in the geological record where a discontinuity is present. So, the Great Unconformity refers to the large gaps left in the planet's rock record (ahem... nothing to do with music...) where young sedimentary rocks sit on top of much older metamorphic rock. For example, in the Grand Canyon, a layer of sandstone dating back to 500 million years ago sits on top of a 1.7-billion-year-old metamorphic rock layer. There are similar unconformities around the world.

Why is this so interesting you ask? Well, among other things, these gaps  leave a limited record precisely when life was advancing very quickly. 500 million years ago or so, new forms of multicellular life forms appeared, something that is come to be known as the Cambrian explosion. In the article referred to during the Nature podcast, researchers from the University of Wisconsin and Pomona College link changes in ancient ocean chemistry to this remarkable transformation of life. One important change is that of biomineralisation, by which organisms started using minerals, such as calcium carbonate, to build structures such as shells and skeletons. The formation of the Great Unconformity "may have been an environmental trigger for the evolution and mineralisation and the 'Cambrian explosion'", the researchers say.

Now that you have created your videos with either your PC or your Mac, you are ready to share them with the world. I find Vimeo very easy to use and quite flexible in terms of content, size of files and things of that sort. In this video I show you try quickly how to create an account and how to upload your masterpiece.

As usual, let me know what you think.

http://vimeo.com/36840631

## Videocasting with a PC

Talking to some people about screen capturing and video tutorials, I came across the fact that, although there is some interest in the activity, there is the idea that you need sophisticated tools to create even the simplest video presentation.

In this video I show how some simple videos can be produced by capturing screenshots using a PC with windows installed. The tools that I use are CamStudio and Freemake Video Converter, which are readily available in the web.

As usual, any comments are more than welcome. Enjoy!

http://vimeo.com/36821557

## Happy 155th Birthday Heinrich Hertz

Surely you are familiar with measures of frequency such as the hertz, which tells us about the number of cycles of a wave in a second. This SI unit is named after the German physicist Heinrich Hertz and it so happens that today, 22nd of Feburary it would have been his birthday.

Although Hertz is probably better know for the name of the SI unit, one of his most important contributions to physics is related to the electromagnetic theory of light as proposed by Maxwell. Hertz was the first one to prove the existence of electromagnetic waves and in turn he used them to send and receive radio waves.

Even Google has decided to remember this great physicist by creating a doodle to celebrate his 155th birthday,

Happy 155th Hertz!

## Structured Documents in LaTeX

Continuing with the brief introduction to LaTeX that I posted recently, in this video I discuss the use of LaTeX to produce a document that has a structure similar to that of a book for example. The idea is to build a master file that controls the flow of the document and separates each "Chapter" in separate files. This provides the author with a lot of flexibility in terms of organising content and makes large documents far more manageable than when using a single LaTeX file.

Enjoy and any feedback, comments or suggestions are more than welcome.

http://vimeo.com/36550754

## Using LaTeX to write mathematics

I have been meaning to do something like this for a long time and finally got the courage to do it. A lot of times I get completely horrified by the way in which some documents that contain mathematical notations are mangled (quite literally) by using MS Word. It helps sometimes that some people have access to MathType but still...

So, in this video I intend to provide some help to those that are interested in using LaTeX to include mathematics and  produce their documents. LaTeX is freely available for various platforms. You can obtain MikTeX for  Windows here, and MacTeX for Mac here. There are a great variety of editors to choose from; in this video I recommend TeXmaker, which I believe provides quite a lot of help to those of us that still are attached to the pointing and clicking of MS Word.

Let me know what you think! Any feedback is always welcome.

http://vimeo.com/36401920

## Proper mathematicians do it also when in the loo... Blackboard in the Newton Institute

The Newton Institute for Mathematical Sciences in Cambridge is distinguished for many things, among them the number of blackboards around the building... even in the toilets... Great!

## Royal Society of Chemistry Library

Very nice working/reading space in the Royal Society of Chemistry and in the heart of central London!

## Interview with Samuel Richards - Quantum Tunnel Podcast

The Quantum Tunnel Podcast brings you an interesting chat with Samuel Richards, an undergraduate student at the University of Hertfordshire who has recently had the opportunity to collaborate with researchers in the University of Sydney and the Australian Astronomical Observatory working on SAMI.

News

Travelling faster than light

One of the cornerstones of modern physics is the idea that nothing can travel faster than the speed of light. Nonetheless, researchers at the Gran Sasso facility in Italy have recently reported on the recording of particles travelling at speeds forbidden by the theory of relativity.

Researchers on the Oscillation Project with Emulsion-Tracking Apparatus or OPERA recorded the arrival times of neutrinos sent from CERN. The trip would take a beam of light 2.4 milliseconds to complete, but after three years of experi-ments, the scientists report on the arrival of 15,000 neutrinos sixty billionths of a second earlier. The result is so unexpected that the OPERA researchers say that they hope the physics community would scrutinise their experiment and help un-cover any flaws. The results have been reported in the ArXiV.

Good-bye Tevatron

At the end of September the Tevatron facility near Chicago fires its last particles af-ter US federal funding ran out. During its more than 25 years, the Tevatron has without a doubt left a rich legacy, for instance one of natures heaviest elementary particles, the top quark, was found here.

The Tevatron was run by the Fermi National Accelerator Laboratory or Fermilab, where since 1985 scientist have been accelerating protons and antiprotons around its 6km ring in order to unlock the secrets of the Universe. The closure of the facility is indeed a solemn occasion, at a time when budgets for science are increasingly being squeezed.

Amazon dam halted again
A Brazilian judge has suspended work on the Belo Monte hydroelectric plant in the Amazon Jungle. In previous podcasts we have reported in the on and off plans for the plant.

In a ruling posted last week, the judge, Carlos Eduardo Martins, said he halted con-struction of the dam because it would harm fishing by indigenous communities in Para State. Back in February the construction was halted by another judge, but the ruling was overturned. The Brazilian government strongly backs the project and it has reported that they will appeal the new ruling.

## Entrevista con Pável Ramírez - Quantum Tunnel Podcast en Español

Puedes descargar este podcast en iTunes o Feedburner.

En esta ocasión el Quantum Tunnel Podcast les ofrece una plática que hemos tenido con Pável Ramírez quien se encuentra realizando estudios doctorales en el Imperial College en Londres en el área de óptica.  Su línea de investigación durante el doctorado está relacionada con el aumento de la profundidad de campo.

Durante la entrevista Pável recomienda ver la película El Violín, dirigida por Francisco Vargas.

Noticias

Viajando más rápido que la luz
Uno de los pilares de la física moderna es la idea de que nada puede viajar más rápido que la velocidad de la luz. Sin embargo, investigadores en las instalaciones del Gran Sasso en Italia, han reportado recientemente el hallazgo de partículas que viajan a velocidades prohibidas por la teoría de la relatividad.

Los investigadores del Oscillation Project with Emulsion-Tracking Apparatus u OPERA por sus siglas en inglés registraron los tiempos de llegada de neutrinos enviados desde CERN. El viaje le tomaría a un rayo de luz 2.4 milisegundos, pero después de tres años de experimentos, los científicos informan de la llegada de 15.000 neutrinos unos sesenta billonésimas de antes. El resultado es tan inesperado que los investigadores de OPERA dicen que esperan que la comunidad de la física pueda escrutinar sus experimentos y ayudar a descubrir donde está la falla. Los resultados han sido reportados en el arXiv.

Despedida al Tevatron

A finales de septiembre la instalación Tevatron cerca de Chicago, disparó sus últimas partículas después de que se terminara el presupuesto aportado por el gobierno federal de los Estados Unidos. Durante sus más de 25 años, el Tevatron dejasin lugar a dudas, un rico patrimonio, por ejemplo, una de las partículas más pesadas de la naturaleza, el top quark,  fue hallado aquí

El Tevatron fue dirigido por el Fermi National Accelerator Laboratory o Fermilab, donde desde 1985 los científicos han estado acelerando protones y antiprotones alrededor de un anillo de seis kilómetros con el fin de descubrir los secretos del Universo. El cierre de la instalación es sin duda una ocasión solemne, en un momento en que los presupuestos para la ciencia son cada vez más reducidos.

Presa en el Amazonas se detiene de nuevo

Un juez brasileño ha suspendido las obras de la central hidroeléctrica de Belo Monte en el Amazonas. En podcasts anteriores hemos informado acerca de los cambios de planes que la planta ha sufrido.

En un fallo publicado la semana pasada, el juez, Carlos Eduardo Martins, dijo que detuvo la construcción de la presa, ya que perjudicaría la pesca de las comunidades indígenas del estado de Pará. En febrero la construcción fue interrumpida por otro juez, pero la sentencia fue revocada. El gobierno de Brasil apoya firmemente el proyecto y se ha reportado que apelarán el nuevo fallo.

## Online/Offline Communities - Science on Line London 2011

This year I had the great opportunity of participating in the discussions of one of the breakout session in the SOLO11 Conference. The topic of the session was the importance of offline communities in online networking. The session was organised by Eva Amsen and co-hosted by Paula Salgado and myself.

It seemed to us quite interesting the fact that people were coming together to an event about science online. Why not organise it solely as an online event? Is it because communities work better when there is support offline?

Eva started off the discussion with some examples of offline communities moving online. She talked about the Node,  a community that started as a suggestion from an existing network of developmental biologists. Other examples included the ArXiv, and Facebook. Here some of the things that Michael Nielsen mention in his opening presentation resonated with what was being discussed: these communities started as small groups, and that is why they worked.

Paula talked to us about her experience in the online and offline communities, including I'm A Scientist, Get Me Out Of Here. Incidentally, you can listen to the interview she gave me for the Quantum Tunnel Podcast about her involvement with this programme. She also mentioned Science is Vital.

As for me, I had the pleasure to talk about my involvement with the organisation of  UKSciTweetups. UK Science Tweetup or UKSciTweetup is a quasi-regular meeting of scientists and sci-curious tweeps, usually on a weekday evening at a pub. Attendees are usually people that use twitter and who are interested in scientific topics. The tweetups are organised and followed-up using a hashtag: #ukscitweetup; anyone interested in the tweetups just need bookmark and/or subscribe to a twitter search for the hash tag. Everyone is  welcome, you don't have to be a scientist, but you must be interested in science.

There has been some debate as to why UK is used in the hashtag since most of the events happen in London, where the events first started. The standard answer is that anyone in the UK can start their on chapter and I believe there have been some successful events in Bristol and Manchester but having more would be great.

In my opinion, there seems to be a general misconception that online communities are what it says in the can - simply and exclusively online. This is and should not be true. The thing to remember is that they are first and foremost communities: collections of people who share a common interest, aim or goal. The fact that they start coming together online does not preclude them from meeting offline, and by doing so they enrich their experience and can be beneficial as the ties between members can become more meaningful and has an impact in the way people use the community.

Meeting offline goes beyond the mere face-to-face interaction with other members as usually people tend to bring people who either are not in the online community (in this case twitter) or are users, but do not interact with other members.

In my experience, it has been very enriching to take part in organising some tweetups but I must admit that keeping momentum can be a hard thing to do. Having the meetings at a pub makes it easier for people to come and go (there was one organised to coincide with the late opening of the Science Museum, but it was a disaster trying to meet with people).

More recently I have not had as much time but that is not to say that other advocates are not active. It is important to mention that the aim of the events is simply to socialise with other people interested in science, so other than the hashtag there is no formal organisation and events tend to happen quite organically.

Having online communities is nothing new, they seem to appear and disappear like fairy lights (MySpace anyone? Google+?). The inherent connectivity provided by the web offers a very convenient way for people to meet others with common interests, or to seek out people to help them with problems or issues they face. However, there are many limitations to this end in terms of building a strong community. Meeting offline con address some of this issues. Online interactions are relatively easy to establish, but they tend to be transient - members don’t log back in or move to the latest networking tool. In that sense it becomes easier when the virtual space provided becomes a bit more tangible.

Going offline:

So why go offline? Being behind the computer screen provides with a certain sense of safety but there are benefits in going offline. First and foremost meeting people we chat with online makes them real. The anonymity of the internet provides a the ease of starting a relationship but there is nothing like a handshake to consolidates it. Spending some time actually chatting in a conversation down the pub for example, rather than reading each individual utterance in your twitter timeline, allows for what I would call true bonding. Participants leave feeling that they have truly connected with peers - for instance by learning finer details about them than an online discussion permits.

Having eye contact when someone and being able to read their body-language makes a huge difference - and can increase or decrease the interaction with that person. Given that members presumably have interacted online in the past makes it much easier than meeting complete strangers and things flow much quicker.

If I were asked about my top tips to build an online-offline community I would have to include:

1. Define a purpose or a cause the group cares about: In the case of UKSciTweetup is science, in a very general definition of the word. The group includes a bunch of physicists, astronomers, mathematicians, biologists, chemists, and most importantly their friends (as we like to put it).
2. Build conversation: in the case of UKScitTweetup engaging with the community happens naturally (via twitter) and using the same logic of being free to follow/unfollow people. UKSciTweetup is open to anyone that engages in the conversation and turn up at the pub. This opens up the doors to the members to feel that they have an opportunity to be involved in the overall running of the events and this therefore translates into a more cohesive community.
3. Building momentum: Momentum is a huge factor and keeping it going can be a hard thing to do. Once you get some steam, things flow much better and people get more involved. Nonetheless, this is easier said than done. Creating events and meetups for the online community is a great way to keep things going.
4. Give people the opportunity to volunteer: If people feel like they can contribute and are keen to participate, the benefit is for the community. Things can be as simple as making recommendations, organise parts of meetups or simply disseminate information. (Anyone interested in organising the next event BTW?).

It is obvious that we are now in an era of online culture. However, that does not mean that we cannot build or leverage an offline community to help the online one or vice versa. It might sound a bit confusing, but there are common features in both and these should be exploited to benefit the community.

## Lion and Air Display don't like each other

I am generally quite happy with using a Mac and things seem to be going quite well with my machine. Nonetheless, I could not resist upgrading my operating system from Leopard to Lion... after all, Apple markets is as "the most advanced desktop operating system". The update itself happened without a glitch, but the machine seemed to have become more sluggish. I assumed it was the number of applications that I had installed and the fact that some of them, such as Maple 9.5 and the version of PhotoShop that I had relied on the usage of Rosetta to work. I got rid of the newly obsolete software, but this did not sort the issues.

One of the more annoying issues, even more than the lack of malleability in Launchpad, was the very insufferable fact that the screensaver acquired a mind of its own: it would just spring into action on its own even when I was typing or using the mouse... After searching for a solution, the only thing that worked was to turn the screensaver off... Now, this is not ideal. But now I think I have found the answer: the problem was the limitation that Air Display has when installed in Lion.

Avatron, the makers of Air Display (a screen extension software) know about this and although they mentioned that only certain models are affected, I found that as soon as I got rid of Air Display not only my machine did not run into troubles with the screensaver but also woke up from the horrendous sluggishness it had been suffering.

How to uninstall Air Display:

• Go to Applications -> Utilities
• Run the "Uninstall Air Display"
• The machine will automatically re-start
• Et voilà

## So, what is the Higgs boson?

One of the most ambitious dreams of physicists is the description of all physical forces as a single set of mathematical relations; this is commonly referred to as unification. All observed phenomena are said to be described by 5 forces: gravity, magnetism, electricity, weak force and strong force.

Unification has happened in some cases, for example in the 1860's James Clerk Maxwell showed that magnetism and electricity are described by a single set of equations. This is why some people talk about four forces after having unified electricity and magnetism into something called electromagnetism. Something similar happened in the 70's when Abdus Salam, Sheldon Glashow and Steven Weinberg unified the weak nuclear force and electromagnetism .

One can ask how forces are transmitted and the current answer from physics would say that they are not transmitted directly between objects, instead the description indicates that forces are described by intermediaries called fields. In other words, all forces in nature are mediated by fields which result from the exchange of particles that the Standard Model called gauge bosons. For instance, in the case of  the electromagnetic force, the interaction of electrically charged particles happens thanks to the photon which is the exchange particle for this force. Similarly, for the weak force - a repulsive short-range interaction responsible for some forms of radioactivity is governed by the W and Z bosons.

The short-range of the weak force, and its weakness comes about because the W and Z bosons are very massive particles, unlike the massless photon. In 1983, scientists in CERN discovered the W and Z bosons and thus the so-called electro-weak theory has convincingly been verified. However, the origin of their masses is still a mystery. The best explanation at the moment is the Higgs mechanism.

The theory shows a symmetry between the photon, W and Z; nonetheless, this symmetry is spontaneously broken and it is thought that this breaking is responsible for the mass of the W and Z bosons. It is thought that there is a field, called the Higgs field, which is responsible for the genesis of mass. This field is named after the Scottish physicist Peter Higgs. Now, we mentioned above that every field has an associated particle, in the case of the Higgs field we have the Higgs boson. The Higgs boson is the only particle, from the Standard Model, that has not been observed. Its existence would explain how most of the known elementary particles become massive, and would explain the difference between the massless photon and the massive W and Z bosons. The Large Hadron Collider is expected to provide experimental evidence of the existence (or not) of this particle.

## I'm not a scientist, but I had a go... Student during work experience

During the last few days Daniel Zheng was visiting me and had a chance at working on some problems using graph theory and networks. Here is what he has to say about this week…

I’m now coming to the end of my placement, having finished writing the (surprisingly complicated) Octave/Gnuplot script to plot a graph of collaboration networks for Medicine during the year 2007. I’ve definitely learned a few things, such as not to be afraid of command-line software, basic operations in Octave and MATLAB® and that it is much more satisfying creating a graphic diagram completely from scratch, especially when it involves hours of typing repeated commands. Computers are very interesting when you can interact with their underlying, fundamental workings, and I can now see how lucky we are today to have beautifully polished operating systems that don’t spit out pages of error messages when you forget that the file name begins with a capital.

I’ve actually really enjoyed the last few days, and I think it’s given me a taste of what university maths & physics might be like; hopefully that’s what I’ll be doing for four years so its nice to be sure I’ll like it! Learning these sorts of computer skills is also likely to strengthen my application for those exact courses, and I do feel like I’ve stretched the boundaries of my own knowledge (if not, as correctly predicted, that of the wider scientific community). Most of all, though, I’m incredibly grateful to Dr Rogel-Salazar for giving up his time and his office space to teach me all of this, for troubleshooting my computer when things went wrong, and (of course) for getting me free food at the faculty barbeque. It’s been a very intriguing and different experience to what I’m used to at school, and hopefully he’ll continue to provide this great opportunity for others like me; anyone who can, should definitely give it a go.

Anyway that’s enough from me, so I’ll be off now…

## I'm not a scientist, but let me have a go... Student during work experience

This week, yet another enthusiastic student is doing a bit of work experience with me. This time it is about graph theory, network analysis and their applications. You never know, he might even help me overcome the deafening silence of the Quantum Tunnel Podcast!

My name is Daniel Zheng and I am a sixth form student at Camden School for Girls. I am about to begin studying for my A2s, and by the end of next year I should have full A-levels in Maths, Further Maths, Physics and Chemistry, and an AS in English Literature. I am hoping to study Maths and Physics at university, and would like to have a career in some sort of science-based industry or field. As well as a keen interest in science and maths, in my spare time I play the French Horn, go rock climbing, play squash and as much more as I can fit in!

Having read many books and articles about scientific progress and advancement, I have always wondered what it’s actually like to work in an active research centre. This work experience is a very good opportunity for me to do that (even if my tasks aren’t likely to change the course of science as we know it…) and get a feeling of how universities operate. I already feel like I’ve learnt a few things about the diverse and interlinked nature of supposedly ‘separate’ fields, and hopefully there will be much more to find out…

## Now reviewing: Heisenberg's Quantum Mechanics

Now reviewing: Heisenberg's Quantum Mechanics

## Leonhard Euler - Quantum Tunnel Podcast

Leonhard Euler (1707-1783) was Switzerland’s foremost scientist and one of the three greatest mathematicians of modern times (the other two being Gauss and

Euler was a native of Basel and a student of Johann Bernoulli at the University, but he soon outstripped his teacher. His working life was spent as a member of the Academies of Science at Berlin and St. Petersburg. He was a man of broad culture, well versed in the classical languages and literatures (he knew the Aeneid by heart), many modern languages, physiology, medicine, botany, geography, and the entire body of physical science as it was known in his time.  His personal life was as placid and uneventful as is possible for a man with 13 children.

Though he was not himself a teacher, Euler has had a deeper influence on the teaching of mathematics than any other man. This came about chiefly through his three great treatises: Introductio in Analysin Infinitorum (1748); Institutiones Calculi Differentialis (1755); and Institutiones Calculi Integralis (1768-1794). There is considerable truth in the old saying that all elementary and advanced calculus textbooks since 1748 are essentially copies of Euler or copies of copies of Euler.

He extended and perfected plane and solid analytic geometry, introduced the analytic approach to trigonometry, and was responsible for the modern treatment of the functions $latex log x$ and $latex e^x$. He created a consistent theory of logarithms of negative and imaginary numbers, and discovered that $latex log x$ has an infinite number of values. It was through his work that the symbols $latex e$, $latex pi$, and $latex i$ became common currency for all mathematicians, and it was he who linked them together in the astonishing relation $latex e^{pi i} + 1 = 0$. This is a special case of his famous formula $latex exp(itheta) = cos theta + i sin theta$, which connects the exponential and trigonometric functions. Among his other contributions to standard mathematical notations were $latex sin x, cos x$, the use of $latex f(x)$ for an unspecified function, and the use of $latex Sigma$ for summation. He was the first and greatest master of infinite series, infinite products and continued fractions, and his works are crammed with striking discoveries in these fields.

He contributed many important ideas to differential equations: the various methods of reduction of order, the notion of an integrating factor (often called an Euler multiplier), substantial parts of the theory of second order linear equations, power series solutions – all these are due to Euler. In addition he gave the first systematic discussion of the calculus of variations (founded on his basic differential equation for a minimizing curve), discovered the Eulerian integrals defining the gamma and beta functions, and introduced the Euler constant:

$latex gamma = lim_{nrightarrow infty}(1+frac{1}{2} +frac{1}{3}+...frac{1}{n}) = 0.5772...$

which is the most important special number in mathematics after $latex pi$ and $latex e$. He also worked with Fourier series, encountered the Bessel functions in his study of the vibrations of a stretched circular membrane, and applied Laplace transforms to solve differential equations - all before Fourier, Bessel, and Laplace were born. The origins of topology - one of the dominant forces in modern mathematics - lie in his solution of the Königsberg bridge problem and his formula $latex V - E + F = 2$ connecting the numbers of vertices, edges, and faces of a simple polyhedron.

In number theory, he gave the first published proofs of both Fermat's theorem and Fermat's two squares theorem. He later generalized the first of these classic results by introducing the Euler $latex phi$ function; his proof of the second cost him 7 years of intermittent effort. In addition, he proved that every positive integer is a sum of four squares, investigated the law of quadratic reciprocity, and initiated the theory of partitions, which deals with such problems as that of determining the number of ways in which a given positive integer can be expressed as a sum of positive integers. Some of his most interesting work was connected with the sequence of prime numbers, with those integers $latex p>1$ those only positive divisors are 1 and $latex p$. His used the divergence of harmonic series $latex 1+frac{1}{2}+frac{1}{3}+...$ to prove Euclid’s theorem that there are infinitely many primes.

The distinction between pure and applied mathematics did not exist in Euler’s day, and for him the physical universe was a convenient object that offered scope for methods of analysis. The foundations of classical mechanics had been laid down by Newton, but Euler was the principal architect. In his treatise of 1736 he was the first to explicitly introduce the concept of a mass-point or particle, and he was also the first to study the acceleration of a particle moving along any curve and to use the notion of a vector in connection with velocity and acceleration. His continued successes in mathematical physics were so numerous, and his influence was so pervasive, that most of his discoveries are not credited to him at all and are taken for granted by physicists as part of the natural order of things.

However, we do have Euler's equation ns of motion for the rotation 'of a rigid body, Euler's hydrodynamical equation for the flow of an ideal incompressible fluid, Euler's law for the bending of elastic beams, and Euler's critical load in the theory of the buckling of columns. On several occasions the thread of his scientific thought led him to ideas his contemporaries were not ready to assimilate. For example, he foresaw the phenomenon of radiation pressure, which is crucial for the modern theory of the stability of stars, more than a century before Maxwell rediscovered it in his own work in electromagnetism.

Euler was the Shakespeare of mathematics - universal, richly detailed, and inexhaustible.

News

Bilingualism key to language survival
There are about 6000 different languages in the world, but just a handful, including English, dominate. Some mathematical models have shown how dominating languages can lead to the decline and extinction of less popular languages. However. Physicists in Span are challenging this idea. According to Jorge Mira Pérez and his colleagues at the University of Santiago de Compostela earlier models have not taken into account bilingualism which allows both languages to co-exist and evolve.
The researchers compared the results of their model to historical data for the preponderance of Spanish and Galician from the 19th century to 1975 and found that the fit is quite good. They find that both languages can survive so long each is initially spoken by enough people and both are sufficiently similar. The paper was published in the New Journal of Physics.

Periodic Table of Shapes
We are very familiar with the periodic table of elements, whose invention is attributed to Dimitri Mendeleev in 1869 and it has become ubiquitous in many a classroom. The table is a visual representation of the periodic law which states that certain properties of the elements repeat periodically when arranged by atomic number. Researchers at Imperial College London are interested in creating a periodic table of shapes which would become a very useful resource for mathematicians and theoretical physicists looking for shapes in three, four and five dimensions that cannot be broken into simpler shapes. These basic blocks are known as “Fano variaties” and for them to represent practical solutions to physical problems, researchers need to look at slices of the Fano varieties known as Calabi-Yau 3-folds which give possible shapes of the curled extra dimensions required by string theory.

Enlarging Schrödinger’s cat
Quantum mechanics tell us that a quantum object can exist in two or more states simultaneously, this is called a quantum superposition and usually it can be seen in very tiny objects. Nonetheless researchers in Austria have recently demonstrated quantum superposition in molecules composed of up to 430 atoms each.
Erwin Schrödinger proposed a thought experiment to illustrate the apparent paradoxes of quantum theory in which a cat would ne poisoned or not depending on the state of a quantum object. Since the object could be in a superposition of states, the cat would thus be dead and alive at the same time. This highlights the difference between the classical and the quantum worlds and poses the question as to how big would the objects have to be in order to perceive their quantumness.
Markus Arndt and colleagues have shown the observation of quantum effects in large molecules tailor-made for the purpose – up to 6 nanometres across and with up to 430 atoms, several times larger than molecules used in similar experiments in the past.

Female hormone holds key to male contraceptive
Contraceptive pills have been in the market for 50 years not, but are only available for women. Scientists had known that high doses of certain hormones stopped ovulation, but extracting the quantities needed for scale production was too difficult. It was not until invention of progestine by Mexican chemist Luis Miramontes and co-workers that lead to the creation of oral contraceptives.

Recently, two studies published in Nature (1, 2)  point to a breakthrough to design a new class of contraceptive pills. Researchers have shown how sperm sense progesterone, a female sex hormone, which serves as a guide to the egg. Progesterone activates a molecular channel called CatSper, which floods sperm cells with calcium. Problems with progesterone sensing could explain cases of infertility. The results could pave the route to coming up with a male contraceptive pill in the future.

## Ig Nobel Awards Tour

Last Thursday, 17th March, I celebrated St Patrick's day by attending an event at Imperial College London: the Ig Nobel Awards tour.

The show was presented by Marc Abrahams, organiser of the Ig Nobel prizes, editor of the Annals of Improbable Research. It featured some Ig Nobel Prize winners and other 'improbable' researchers.

Matija Strlic, from UCL, talked about “the Smell of Old Books“.

Elena Bodnar, 2009 Ig Nobel Prize winner in public health, presented her emergency brassiere, which can be quickly converted into a pair of protective face masks, one for the brassiere wearer and one to be given to some needy bystander. She demonstrated this invention and the idea was a also to introduce a device worn by males. However the "prototype" disappeared and a bit of improvisation had to be done...

Dan Bebber, one of the winners of the 2010 Ig Nobel Prize for Transportation, talked about using slime mould to model an effective railway network. In the experiment, cities were represented by porridge oats that were linked to one another as the slime mould grew.

John Hoyland, editor of the “Feedback” column in New Scientist Magazine talked about some interesting oddities.

An enjoyable evening full of geekiness!

## Sir Isaac Newton (Parte II) - Quantum Tunnel en Español

Puedes descargar este podcast en iTunesFeedburner.

En el episodio anterior mencionábamos que en 1669 Newton experimentó lo que podríamos llamar un año de genialidad durante el cual realizó algunos de los más notables descubrimientos en la historia de la ciencia, sin embargo no siempre estaba interesado en hacer dichos descubrimientos públicos.

Los Principia Mathematicae siempre ha sido un libro difícil de leer, puesto que esta escrito en un estilo frío y remoto, tal vez bastante apropiado para la grandeza de los temas que aborda. Además la densa cantidad de matemáticas empleada consiste casi únicamente en geometría clásica, la cual era muy poco cultivada en ese entonces, y lo es mucho menso hoy en día.

Después de la gran actividad llevada acabo en la creación de los Principia, Newton una vez más dejó de lado la ciencia. En 1696 dejó Cambridge y se trasladó a Londres para convertirse en Jefe de la Casa de Moneda. Durante el resto de su vida entró poco en la vida en sociedad pero tuvo oportunidad de disfrutar de su posición única en la cima de su fama científica. Estos cambios en sus intereses y en su ambiente no hicieron que disminuyeran sus poderes intelectuales. Por ejemplo, una tarde, al final de un arduo día de trabajo acuñando monedas escuchó acerca de el problema de la braquistrocrona propuesto por Johann Bernoulli quien lo describió como un problema para los más agudos intelectos matemáticos del mundo entero, y así Newton lo resolvió esa misma tarde antes de ir a dormir.

De gran interés para la ciencia es también su publicación de Opticks en 1704. En este libro asimiló y extendió su trabajo acerca de la luz y el color. Como apéndice agregó sus famosas Queries o Cuestiones, que son especulaciones en áreas de la ciencia que se encuentran mucho más allá del entendimiento científico en aquel entonces. Muchas de estas cuestiones tienen que ver con la preocupación constante que Newton tenía para con la química (o alquimia como se le llamaba en su tiempo). Así pues formuló varias conclusiones tentativas pero largamente consideradas, siempre fundamentadas en experimentos, acerca de la probable naturaleza de la materia. Y aunque el probar sus ideas tuvo que esperar la llegada del refinado trabajo experimental de finales del siglo XIX y principios del XX, sus ideas generales han sido corroboradas al menos en cuanto a nociones generales se refiere.

Newton ha sido siempre considerado y descrito como el estereotipo del racionalista, como la personificación de la Edad de la Razón. Tal vez sería más preciso pensar acerca de él en términos medievales - como un místico intuitivo, consagrado y solitario, para quien la ciencia y las matemáticas eran herramientas para descubrir los misterios del Universo.

Noticias

Una clave del cáncer de mama es hallada

Expertos en cáncer han identificado un gen que causa una forma particularmente agresiva de cancer de mama. El nombre que se ha dado a este oncogen is ZNF703 y se encuentra sobreactivado en uno de cada doce canceres de mama. Científicos trabajando para Cancer Research UK llevaron a cabo la investigación y mencionan que el gen era uno de los candidatos clave para el desarrollo de nuevas medicinas contra el cáncer de mama. El estudio fue publicado en la revista EMBO Molecular Medicine.

Físicos ponen en reversa al laser

Creo que la gran mayoría de nosotros está familiarizado con la luz laser y por tanto parecería un tanto extraño el pensar en un laser que absorbe un rayo brillante en vez de emitirlo. Sin embargo, científicos de la Universidad de Yale han recientemente reportado en la revista Science el desarrollo de un aparato que convierte haces laser en calor.
Cao y sus colegas utilizaron una oblea de silicón y un laser infrarojo sintonizable para sus experimentos. Lo que hacen es dividir el haz laser en dos e iluminan con él ambos lados de la oblea de silicón. La parte anterior y posterior de la oblea funcionan como espejos, mientras que el silicón en medio juega las veces del medio dentro de una cavidad laser. Al cambiar la frecuencia del laser, así como otras propiedades, los fotones son atrapados entre las superficies de la oblea. Mientras los fotones rebotan entre las superficies, el silicón los absorbe hasta que todos desaparecen y son convertidos en calor.

Oliendo vibraciones cuánticas

Una de las teorías más arraigadas acerca de la percepción de olores es que las formas de las diferentes moléculas proveen las pistas que nuestros cerebros registran como olores. Sin embargo, se ha reportado recientemente que algunas moscas de la fruta pueden distinguir entre dos moléculas con formas idénticas, lo cual nos da la primera evidencia experimental que soporta la teoría de que el sentido del olfato opera detectando vibraciones moleculares.

Efthimios Skoulakis del Alexander Fleming Biomedical Sciences Research Center en Vari, Grecia, llevó a cabo los experimentos con moscas de la fruta. El equipo inicialmente puso a las moscas en un laberinto y las dejaron escoger entre dos ramas, una contenía un químico con fragancia tal como acetophenon, un ingrediente común en perfumes, y la otra una versión deuterada. Si las moscas estuvieran detectando olores basándose en forma únicamente, entonces no podrían diferenciar entre ambas ramas. Los científicos encontraron que las moscas preferían el acetophenon ordinario.

Projecto de prese brasileña es bloqueado

En el episodio anterior reportamos la aprobación para la construcción de una controversial presa en el Amazonas, la planta hidroeléctrica de Belo Horizonte, la cual es la tercera planta de su tipo en el mundo. Los planes han sido suspendidos por un juez brasileño debido a asuntos ambientales.

El juez Ronaldo Desterro detuvo los planes de construcción puesto que no cumplian con los requerimientos ambientales debidos, asimismo, el banco nacional de desarrollo tiene prohibido financiar el proyecto. La licencia de construcción fue otorgada en Enero.

Conferencia de Comunicación de la Ciencia en Londres

La British Science Association anunció recientemente su congreso anual de dos días acerca de la comunicación de la ciencia. El evento tiene como objetivo el abordar algunos de los temas principales que enfrentan los comunicadores de la ciencia en el Reino Unido. El evento se llevará acabo los días 25 y 26 de Mayo en King's Place, King's Cross, en Londres. El tema principal de la conferencia será "dialogo en línea" y se exploraran usos innovativos de los medios en línea para establecer dialogo entre el público y la ciencia. El registro para la conferencia abrió el 14 de Febrero y cerrará el 13 de Mayo. Para mayor información dirijanse a la página de internet de la asociación.

## The Large Hadron Collider - Quantum Tunnel Podcast

The Large Hadron Collider is located 300 feet underneath the French-Swiss border outside Geneva and is the world's biggest and most expensive particle accelerator. It is designed to accelerate  protons to energies of 7 trillion electron volts and then smash them together to recreate the conditions that last prevailed when the universe was less than a trillionth of a second old.

The collider started smashing particles on March 30th, 2010, after 16 years and \$10 billion. The new hadron collider will take physics into a realm of energy and time where the current reigning theories simply do not apply, corresponding to an era when cosmologists think that the universe was still differentiating itself, evolving from a primordial blandness and endless potential into the forces and particles that constitute modern reality.

One prime target is a particle called the Higgs boson that is thought to endow other particles with mass, according to the reigning theory of particle physics, known as the Standard Model.

The LHC is part of CERN, which born amid vineyards and farmland in the countryside outside Geneva in 1954 out of the rubble of postwar Europe. It had a twofold mission of rebuilding European science and of having European countries work together. Today, it has 20 countries as members. It was here that the World Wide Web was born in the early 1990s. The lab came into its own scientifically in the early 80s, when Carlo Rubbia and Simon van der Meer won the Nobel Prize by colliding protons and antiprotons there to produce the particles known as the W and Z bosons, which are responsible for the so-called weak nuclear force that causes some radioactive decays.

Bosons are quanta that, according to the rules of quantum mechanics transmit forces as they are tossed back and forth in a sort of game of catch between matter particles. The W's and Z's are closely related to photons, which transmit electromagnetic forces, or light.

The innings of the collider are some 1,232 electromagnets, weighing in at 35 tons apiece, strung together like an endless train stretching around the gentle curve of the CERN tunnel. In order to bend 7-trillion-electron-volt protons around in such a tight circle these magnets have to produce magnetic fields of 8.36 Tesla, more than 100,000 times the Earth's field, requiring in turn a current of 13,000 amperes through the magnet's coils. To make this possible the entire ring is bathed in 128 tons of liquid helium to keep it cooled to 1.9 degrees Kelvin, at which temperature the niobium-titanium cables are superconducting and pass the current without resistance.

Running through the core of this train, surrounded by magnets and cold, are two vacuum pipes, one for protons going clockwise, the other counterclockwise. Traveling in tight bunches along the twin beams, the protons will cross each other at four points around the ring, 30 million times a second. During each of these violent crossings, physicists expect that about 20 protons, or the parts thereof - quarks or gluons - will actually collide and spit fire.

Two of the detectors are specialized. One, called Alice, is designed to study a sort of primordial fluid, called a quark-gluon plasma, that is created when the collider smashes together lead nuclei. The other, LHCb, will hunt for subtle differences in matter and antimatter that could help explain how the universe, which was presumably born with equal amounts of both, came to be dominated by matter.

The other two, known as Atlas and the Compact Muon Solenoid, or C.M.S. for short, are the designated rival workhorses of the collider, designed expressly to capture and measure every last spray of particle and spark of energy from the proton collisions.

NEWS

Key breast cancer driver found

Cancer experts have identified a gene which can cause a particularly aggressive form of breast cancer to develop. The name given to this new oncogene is ZNF703 and it is overactive in one of 12 breast cancers. Scientists working for Cancer Research UK carried out the research and they mention that the gene was “prime candidate” for the development of new breast cancer drugs. The study was published in the EMBO Molecular Medicine Journal.

Physicists reverse the laser

We are very familiar with laser light, and as such it would seem very odd to thing about a laser that sucks in a bright beam rather than emitting it. However, scientists from Yale have recently reported in Science the development of a device that converts laser beams into heat.

Cao and co-workers uses a 110-micrometre silicon wafer and a tunable infraread laser in their experiments. They split the laser beam into two and shine it into both sides of the silicon wafer. The front and back of the silicon slice act as mirrors and the silicon in between would be similar to the medium inside a laser cavity. By tuning the frequency of the incoming laser beam as well as other properties, the photons are trapped between the surfaces of the silicon. As the photons bounce back and forth, the silicon absorbs them until all photons are sucked up by the device and converted into heat.

Smelling quantum vibrations

It has been widely believed that the different shapes of molecules provide the clues that our brain registers as smells. However, it has recently been reported that some fruit flies can distinguish between two molecules with identical shapes, providing the first experimental evidence to support a controversial theory that the sense of smell can operate by detecting molecular vibrations.

Efthimios Skoulakis of the Alexander Fleming Biomedical Sciences Research Center in Vari, Greece, carried out the experiments on fruit flies. The team initially placed fruit flies in a simple maze that let them choose between two arms, one containing a fragrant chemical such as acetophenone, a common perfume ingredient, the other containing a deuterated version. If the flies were sensing odours using shape alone, they should not be able to tell the difference between the two. In fact, the researchers found that flies preferred ordinary acetophenone.

Brazilian dam project blocked

In the previous episode we reported on the approval of the construction of a controversial dam in the Amazon, the Belo Horizonte hydroelectric plant, the third largest plant of it's kind in the world. The plans have now been suspended by a Brazilian judge over environmental concerns.

Judge Ronaldo Desterro halted the plans for the construction because environmental requirements have not been met, also, the national development bank has been prohibited from financing the project.

Science Communication Conference in London

The British Science Association has recently announced its annual two-day Science Communication Conference. The event aims to address some of the key issues facing science communicators in the UK. In order to do that, the conference brings together people involved in public engagement with a range of backgrounds including scientists, charities, universities, press offices and policymakers.
The event will take place on the 25th and 26th of May at King's Place in King's Cross in London.  Registration opened on February 14 and will close on May 13th. For more information please visit their website.

## Technology of the past

It is amazing how much we take for granted when it comes to technology. I am still surprised that some youngsters do not know for example how to list the files in a folder using a command line, and cannot do much without a graphical interface.

This video is a great example of what how children try to make sense out of technology of the (not so remote) past. Enjoy!

## This has made my boxing day - Darwin Ichthys, with feet and all...

This has made my boxing day - Darwin Ichthys, with feet and all...

## Winter Solstice Lunar Eclipse

William Castleman shot an amazing time lapse video of last night’s Winter Solstice Lunar Eclipse on the darkest day in 372 years. It was shot from Gainesville, Florida from 1:10 AM EST (6:10 GMT) to 5:03 AM EST (10:03 GMT).

## The illustrated guide to a Ph.D.

Imagine a circle that contains all of human knowledge:

By the time you finish elementary school, you know a little:

By the time you finish high school, you know a bit more:

With a bachelor's degree, you gain a specialty:

A master's degree deepens that specialty:

Reading research papers takes you to the edge of human knowledge:

Once you're at the boundary, you focus:

You push at the boundary for a few years:

Until one day, the boundary gives way:

And, that dent you've made is called a Ph.D.:

Of course, the world looks different to you now:

So, don't forget the bigger picture:

Keep pushing.

Reproduced under the Creative Commons License from Matt Might http://matt.might.net/articles/phd-school-in-pictures/

## The known Universe

If you ever doubt the beauty of the little corner of the Universe in which we live, you just have to take a look at this film. It was developed by the American Museum of Natural History.

It shows us the known Universe as mapped through astronomical observations. Enjoy!

## 350th Anniversary of the Royal Society – Quantum Tunnel Podcast

The UK’s national academy of science, the Royal Society, is celebrating its 350th anniversary. The society held its first meeting on November 28, 1660 after a lecture by Sir Christopher Wren.

The Society was to meet weekly to witness experiments and discus scientific topics. The society became the "club" of Britain's best brains: in 350 years, there have been just 8,000 members, ranging from Newton, Charles Darwin and Michael Faraday to the DNA pioneers Francis Crick and James Watson, Stephen Hawking and Tim Berners-Lee.
From the beginning, Fellows of the Society had to be elected, although the criteria for election were vague and the vast majority of the Fellowship were not professional scientists. In 1731 a new rule established that each candidate for election had to be proposed in writing and this written certificate signed by those who supported his candidature. This new professional approach meant that the Society was no longer just a learned society but also de facto an academy of scientists.

The society pioneered scientific publishing. Its Philosophical Transactions is the world's oldest continuous scientific publication.

In this, its 350th anniversary, the Royal Society has organised a number of events throughout the year. A very interesting event was the exhibition “350 Years of Science” which presents us with a journey through the Royal Society’s building on Carlton House Terrace and shows us the fascinating history of the Society.

The Royal Society is a great institution and one which has a very important role in today’s World: It supports modern science, financing approximately 700 research fellowships both early and late career scientists, along with innovation, mobility and research capacity grants.

I am pretty sure that in the next 350 years much more history and many more stories will involve the Royal Society. Happy birthday!

News

Science and the Coalition Government in the UK
UK Scientists have on-going concerns for the future of UK science over the Coalition Government’s ‘one size fits all’ plans to cap immigration.
With the new visa system overseas researchers are more likely to find it difficult to get access to the UK due to academic salaries and qualifications being expected to earn fewer visa points than those awarded to other workers. The new plans put a cap of 1,000 visas to the ‘exceptional talent’ tier one visas, which replaces the highly skilled category, while graduate scientists can also apply for 20,700 tier two visas if they already have a job offer.

Rhea’s atmosphere

A team of scientists for the Southwest Research Institute in San Antonio, US, have discovered an atmosphere of oxygen and carbon dioxide on Rhea, the second largest moon orbiting Saturn. The results have been published in the online version of the Science magazine.

Photon Bose-Einstein Condensate

Physicists from the University of Bonn in Germany have developed a Bose-Einstein condensate consisting of photons. Until recently, experts had thought this impossible. The scientists report their results in the journal Nature.
This photonic Bose-Einstein condensate is a completely new source of light that has characteristics resembling lasers. But compared to lasers, they have a decisive advantage, it could be possible to produce lasers with a very short wavelength.