Physics Today’s online staff summarize the most important and interesting news about science from the world's top media outlets.
There are 81 posts for the selected month (August 2016).
Nature: Since the 1990s the Mathematics Genealogy Project (MGP) has been building family trees for professional mathematicians based on their doctoral advisers. An analysis performed by Floriana Gargiula of the University of Namur in Belgium and her colleagues has found that of the more than 200 000 mathematicians in the MGP database, 65% can be traced back to just 24 families. The analysis was done by combining the MGP data with information from Wikipedia and the Scopus bibliographic database. Overall, the analysis found 84 distinct families. The largest family, with 56 387 descendants, is headed by 15th-century physician Sigismondo Polcastro.
New Scientist: In the wake of last week's deadly magnitude 6.2 earthquake in central Italy, the country is preparing for final tests of a national earthquake forecasting and warning system. Italy's Civil Protection Department is developing a system that will collect seismic measurements from around the country and combine that data with mathematical models and historical records. Every three hours the system will spit out a report that predicts the number of earthquakes the country will experience in the next seven days. Warner Marzocchi of the Italian National Institute of Geophysics and Volcanology in Rome says that the system will likely be very good at predicting aftershocks, though it will not be able to predict magnitude. Predicting quakes like last week's will be difficult because of the absence of warning tremors.
New York Times: Fire whirls are tornado-like phenomena that often occur during large fires. They can be extremely damaging because the vortex causes the fire to burn much hotter. Inspired by a video of a fire whirl that ignited on a spill of bourbon in a pond at the Jim Beam distillery in Kentucky, Huahua Xiao, Michael Gollner, and Elaine Oran of the University of Maryland, College Park, have found that the whirls could possibly help in cleaning up oil spills. They poured n-heptane, an ingredient in some fuels, into a pan of water, ignited it, and then channeled air toward the fire to create a vortex. The resulting fire whirl soon changed from a yellow flame to a blue flame, indicating that burning was occurring at a significantly higher temperature and more efficiently, thereby producing less soot. A subsequent test using crude oil had similar results. The blue fire whirl is, as far as the researchers have found, a previously undocumented phenomenon. The Maryland team hopes to test the phenomenon at a larger scale to determine whether it could be useful for oil-spill cleanup.
BBC: When two turbines off the coast of Shetland, an archipelago off northern Scotland, were recently connected to the country's electrical grid, they became the first offshore tidal generators to provide commercial electricity. The two 100 kW generators were installed by Nova Innovation, an Edinburgh-based tidal energy company. Scotland has invested significantly in tidal energy generation because the country has some of the most powerful tides in Europe.
The Guardian: Greenland's ice sheet is one of the largest on Earth. Malcolm McMillan of the Center for Polar Ice Observing and Modeling in the UK and his colleagues recently used the satellite Cryosat-2 to map Greenland with a resolution of 5 km. The satellite uses radar altimetry to measure the height of the surface. By taking images over time, the researchers were able to measure changes in height; an increase in height corresponds to an increase in ice thickness. However, those measurements don't account for changes in density (the top layer could be ice or snow), surface roughness, water content, and other factors. McMillan's team examined the satellite imagery collected between 2011 and 2014 and accounted for all the variations. The scientists calculated that 270 billion tons of ice was lost per year, closely matching previous measurements from other groups using different measurement techniques. They also found that the western part of the sheet experienced more ice loss than the eastern side, and that a region less than 1% of the area of the sheet was responsible for 10% of the ice loss.
Korea Times: South Korea's National Fusion Research Institute announced on 24 August that it has developed a process capable of producing 50 kg of tritium breeder pebbles per year. Tritium, a radioactive isotope of hydrogen with one proton and two neutrons, is a common fuel for nuclear fusion reactors. Unlike hydrogen's other isotope, deuterium, tritium does not occur naturally in large quantities and so has to be artificially produced. Previous processes have not produced significant quantities of the isotope. According to the Institute for Energy and Environmental Research, between 1955 and 1996 the US produced an estimated 225 kg of tritium.
Washington Post: Dark matter accounts for much of the mass in the universe, but it is not evenly distributed. About 83% of the Milky Way's mass is due to dark matter; the percentage is considerably higher for some dwarf galaxies. Now Pieter van Dokkum of Yale University and his colleagues have found a galaxy, called Dragonfly 44, that has roughly the same mass as the Milky Way yet has only 1% as many stars. The researchers estimate that 99.99% of the galaxy's mass is from dark matter. Because Dragonfly 44 is about average when it comes to galactic size, scientists suspect that similarly dark matter–dominated galaxies are relatively common.
BBC: Earthquakes aren't the only phenomena to send seismic waves through Earth's interior. When a large storm forms water, the energy from colliding ocean waves can create weak seismic activity—dubbed a microseism—that travels through the crust. The pressure-wave microseisms from storms have been tracked regularly, but the transverse S waves, which move much more slowly, have never been tied directly to a storm until now. Kiwamu Nishida from the University of Tokyo and Ryota Takagi of Tohoku University used a dense network of seismic detectors off the Japanese coast to measure S waves and pin their source to a storm off the coast of Greenland. Researchers should be able to learn about Earth's interior structure by comparing the propagation of S and P waves from the same storm.
Ars Technica: In April, Russian billionaire and physicist Yuri Milner announced that he was providing $100 million for the research and development of an interstellar probe, a project he dubbed Breakthrough Starshot. The goal of the project is to accelerate tiny spacecraft up to 20% the speed of light so they could reach the closest star system, which includes Proxima Centauri and its newly discovered planet, in just 20 years. Now a team of researchers has calculated just how risky a trip at that speed would be. The scientists found that although heavier atoms in interstellar gas, such as oxygen, magnesium, and iron, could damage the vehicle, they would probably erode the ship's surface by only about 0.1 mm. However, interstellar dust would have a much more significant impact, eroding 1.5 mm of the spacecraft's surface and also causing localized melting as deep as 10 mm. The researchers say that much of the damage could be minimized or avoided by adjusting the spacecraft's design.
The Kepler space telescope has uncovered a bounty of planets orbiting other stars, but many of those worlds are too distant for in-depth study. Now astronomers have discovered an exoplanet far closer to home—4.22 light-years, to be exact—and it's potentially habitable to boot. Proxima b, reported 24 August in Nature, sits in the liquid-water-friendly habitable zone of the red dwarf Proxima Centauri, the smallest of the three-star Alpha Centauri system and the star nearest to the Sun. From telescope data collected between 2000 and 2008, researchers picked out hints of a signal indicating that the star was wobbling with a velocity of about 1.38 m/s, potentially due to the gravitational tug of an orbiting planet. A dedicated observing run earlier this year by the European Southern Observatory's 3.6 m telescope at La Silla Observatory, Chile, confirmed the planet's presence. The radial velocity measurements reveal that the planet circles the star every 11.2 days, an orbit that puts the planet within Proxima Centauri's habitable zone, and has a mass at least 1.1 times that of Earth's. Although those parameters seem to suggest that Proxima b is both rocky and suitable for life, it's important to note that the planet's diameter, density, and precise mass are unknown. And astronomers are unsure whether life could thrive on red dwarf planets, since they are probably tidally locked and frequently doused in UV and x-ray radiation from stellar flares.
Still, the fact that Earth's nearest stellar neighbor hosts a potentially habitable planet is a discovery worth celebrating. It's a moment astronomers had hoped for ever since the 2012 claim of a planet circling another star in the Alpha Centauri system was thrown in doubt after follow-up observations and analyses. The discovery should also provide a boost for the ambitious interstellar mission Breakthrough Starshot, which aims to launch high-speed miniature probes to the Alpha Centauri system. Although there are many obstacles to overcome for launching such a mission, Proxima b certainly represents an enticing target.
Credit: Digitized Sky Survey 2; Davide De Martin/Mahdi Zamani
Here are the best places to learn more about the discovery:
The Washington Post has a nice roundup that emphasizes the limitations in our knowledge of whether Proxima b qualifies as "Earth-like."
At Scientific American, Lee Billings, author of a book on exoplanets, details the discovery and adds helpful context.
A New York Times visualization illustrates the location and orbit of Proxima b along with the radial velocity signal that led to the planet's discovery.
Astronomer Abel Méndez at the University of Puerto Rico at Arecibo's Planetary Habitability Laboratory writes that by one measure Proxima b is the most similar exoplanet to Earth that we know, but that doesn't mean it's the most suitable for life.
Science News: Proposed 10 years ago, quantum data locking is a method for encrypting information by encoding the entire message, not just the encryption key, in a quantum system. Now Daniel Lum of the University of Rochester in New York and his colleagues have demonstrated the technique for the first time. They defined the state of a photon as their message and then encrypted it by using an equation to scramble the photon's wave function. That ensured the photon would arrive at the intended location on the detector only if the receiver knew the same equation. Although the demonstration is an important step toward secure quantum communication, the technique may not be practical when applied to real-world messages.