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A new approach for optical meta-lenses

10 March 2016
The design and construction of large-scale structures is simplified by invoking symmetry.

Humans are contributing to global warming in more ways than previously thought

10 March 2016
Washington Post: Carbon dioxide emissions are not the only culprit contributing to climate change. According to a recent study published in Nature, methane and nitrous oxide emissions are also on the rise due to increased human activity, such as animal agriculture, rice cultivation, and waste disposal. What’s more, those gases are much more potent: “Methane global warming potential is 28 times larger than carbon dioxide, and nitrous oxide is 265 times greater than carbon dioxide,” says Hanqin Tian of Auburn University, one of the study’s coauthors. However, methane lives in the atmosphere for just 12 years and nitrous oxide for about 114 years, compared with CO2, which can hang around for thousands of years. One way to weaken global warming, at least in the short term, say the authors, would be to alter food production methods.

Video game designed to help develop circuits for quantum computers

10 March 2016
New Scientist: Inspired by the crowdsourced game Foldit, in which players work to create viable proteins, Simon Devitt of the RIKEN Center for Emergent Matter Science in Saitama, Japan, and his colleagues have developed a game to help find potential designs for quantum computers. In meQuanics, players are presented circuits as 3D puzzles and are given tools to shrink and reshape the circuits without breaking the functionality of the circuit. This process is based on a technique called topological error correction. The goal is to shrink complex circuits into the smallest shape that maintains the overall structure of the design. Currently, the process is too complex for computers to handle, so RIKEN's team decided to crowdsource the effort. The researchers have a prototype of the game available and have launched a Kickstarter to fund the development of a full version for smart phones.

NASA Mars mission gets postponed until 2018

10 March 2016
New York Times: Because of an irreparable leak in the vacuum enclosure of its InSight spacecraft, NASA has decided to postpone its next Mars mission for two years. The agency had announced in December that InSight would not be ready for its scheduled launch later this month. The two-year delay is necessary because Mars will not come in relatively close proximity to Earth again until 31 July 2018. In the meantime, NASA plans to redesign and build a new enclosure for the spacecraft, although the additional cost of that fix has yet to be determined. InSight—which stands for interior exploration using seismic investigations, geodesy, and heat transport—will use several geophysical instruments to study Mars's deep interior.

Magnetism controls neurons in brains of mice

9 March 2016
IEEE Spectrum: Recently neuroscientists have manipulated the brains of mice using laser light, a technique called optogenetics. However, lasers have limitations, and the technique sometimes requires invasive steps, such as the insertion of fiber-optic cables. Now Ali Guler of the University of Virginia and colleagues have developed a potentially less invasive technique using magnets. It consists of a specially designed gene, dubbed Magneto, that contains two proteins: TRPV4, which acts as an ion channel gatekeeper, and ferritin, which stores iron. Experimenting with mice, the researchers delivered the gene to the striatum, a part of the brain that processes rewards. When an external magnetic field is applied, the ion channels in the striatum open, mimicking the pleasurable effects of dopamine. The team tested the effectiveness of the technique by confining both Magneto-carrying mice and control mice to a small chamber, half of which was magnetized. The researchers found that the Magneto-carrying mice preferred the magnetized side. Magnets have no effect on normal neurons, Guler says. But if synthetic genes like Magneto could be developed and placed strategically in living organisms, the technique could allow scientists to map neural pathways, manipulate behaviors, and compare neurons in different parts of the brain.

Roderich Engelmann

9 March 2016

Simple technique creates superhydrophobic surface from Teflon

9 March 2016
Chemical & Engineering News: Superhydrophobic materials are of interest as a covering to repel water from all sorts of objects. However, those materials are hard to make and easy to damage. Now Chiara Neto of the University of Sydney, Australia, and her colleagues have developed a process for easily creating a superhydrophobic material. Neto's team deposited Teflon on two types of plastics that shrink when heated. When the Teflon-covered materials are heated, the Teflon is forced to contract, creating a superhydrophobic surface that mixes nanometer-scale wrinkles with micrometer-scale folds. Crucially, the surface is nearly as resistant to being scratched as an aluminum coating.

Computer wins game of Go against human champion

9 March 2016
New Scientist: On 9 March an artificial intelligence machine called AlphaGo defeated the world’s best Go player, Lee Sedol, in the first of a five-game series in Seoul, South Korea. In October 2015 AlphaGo, developed by Google, had its first win against a professional player when it beat European champ Han Fui. AlphaGo’s computer algorithm uses deep neural networks to mimic expert players, along with reinforcement learning to improve its play. The victory is considered by many to be a history-making moment because Go is thought to be among the most challenging games for artificial intelligence, more so even than chess.

Five years after Fukushima disaster, contamination is still elevated in fish

9 March 2016
Ars Technica: This month marks the fifth anniversary of the earthquake and tsunami that severely damaged the Fukushima Daiichi nuclear power plant. Because of the radiation leaks, Japan began monitoring radioisotope contamination in nearby agricultural and oceanic regions. The two main isotopes released by the plant are cesium-134 and cesium-137, which have half-lives of roughly 2 years and 30 years, respectively. To determine the extent of the contamination and its rate of decrease, a team of researchers evaluated data collected by Japan's Ministry of Health, Labor, and Welfare about the radioisotope levels in foods between 1 April 2011 and 31 March 2015. The data were somewhat incomplete because of the difficulty of detecting low but still significant levels of contamination, so the researchers applied a statistical model to fill in the gaps. The team found that the vast majority of contamination was present because of the Fukushima disaster. The areas with higher radioisotope levels correspond to the regions in which the plume from the disaster deposited extra radioisotopes. The study also agreed with previous research indicating that bottom-feeding fish have higher cesium levels than other fish.

Statistical association issues statement to clarify use of <em>p</em>-values

8 March 2016
Nature: The scientific community is rethinking the p-value, which traditionally has been considered the gold standard of statistical validity. A new statement from the American Statistical Association (ASA) claims that the continued reliance on and misuse of p-values is “contributing to the number of research findings that cannot be reproduced.” Although researchers tend to interpret p-values of 0.05 or less as indicative of a statistically significant correlation between variables, that is not always true. Scientists also tend to wrongly equate p-values with the importance of a finding. The ASA statement spells out six principles intended to improve the interpreting and communicating of statistical methods in research.

Increased earthquake activity could force Oklahoma to reduce underground gas-and-oil waste disposal

8 March 2016
New York Times: In the wake of three January earthquakes that were among Oklahoma’s largest ever, the state’s Corporation Commission is asking the gas and oil industry to cut back on the underground disposal of liquid waste. That disposal is associated with the huge spike in earthquake activity that has occurred since 2010. Until the three recent quakes, which struck an affluent suburb of Oklahoma City, state politicians had been reluctant to take action against one of the state’s largest industries. The commission has now requested that well operators in two regions of the state—a Connecticut-size area of central Oklahoma and a similar-size area of northwest Oklahoma—cut their waste disposal by 40%. The state is also working to improve its earthquake monitoring network.

Mercury’s dark appearance may be due to ancient graphite crust

8 March 2016
New Scientist: The surface of Mercury is markedly darker than predicted based on measurements of its composition. From data gathered by NASA’s MESSENGER spacecraft, Patrick Peplowski of the Johns Hopkins University and his colleagues say the darkening agent is likely carbon in the form of graphite. Scientists have proposed that carbon was deposited on the planet’s surface by comets, but Peplowski and his team say instead that the carbon may have been present since Mercury’s earliest days, when the planet was covered in a magma ocean. Although most of the minerals found on Mercury would have sunk, graphite would have floated. As the surface cooled, the researchers say, a graphite crust could have formed and then gotten buried by volcanic activity. Subsequent comet impacts would then expose the buried graphite.

Tree rings and Spanish shipwrecks shed light on tropical storm activity

8 March 2016
Washington Post: To study the frequency of hurricanes in the Caribbean Sea before US record keeping began in 1851, researchers looked at some 657 Spanish shipwrecks that occurred between 1495 and 1825. Because hurricane winds and storm surges not only sink ships but also stunt tree growth, the researchers compared their findings with tree-ring data. The scientists found that fewer ships than expected sank during the period 1645–1715, which indicates a relative lack of tropical storms. The lull in hurricane activity coincides with a period of planetary-wide cooling known as the Little Ice Age and a period of low sunspot activity called the Maunder Minimum. "We know that there’s a very strong link between sea surface temperatures and tropical cyclone activity,” says Valerie Trouet of the University of Arizona, one of the researchers involved in the study. Better understanding of the complex interactions between global temperatures and storm activity will become increasingly important for assessing the potential impacts of future climate change.

<em>Nature Physics</em> editorial charges physicists with failure to explain the LIGO advance properly

7 March 2016
The editors adduce only a satire magazine headline as evidence that the public has been deprived of good gravitational-wave understanding.

Scientists criticize legislation that defines wood-burning power plants as carbon neutral

7 March 2016

Science: On 24 February, 65 scientists sent US Senate leaders a letter concerning a provision in an energy bill currently under consideration. The provision requires the federal government to treat the use of forest biomass for power production as carbon neutral, as long as the trees from the forests are replaced and the forests continue to grow trees. Philip Duffy, president of the Woods Hole Research Center in Massachusetts, and the other letter cosigners say the calculation does not take into account the effects that tree removal, processing, consumption, and replanting have on the carbon balance. 

Liquid metal droplets allow for room-temperature soldering

7 March 2016

Nature: Conventional soldering requires heat, but as electronic devices get smaller and more sensitive, that heat can damage the materials used. Now Martin Thuo of Iowa State University in Ames and his colleagues have taken advantage of a phenomenon known as undercooling or supercooling to create tiny droplets of a metal that is normally solid at room temperature. The droplets are encased in a solid shell. To use them as solder, the researchers simply put the droplets into place and then crush them. As the metal is released, it quickly cools and solidifies. By varying details of the production, Thuo's team was able to create particles that range in diameter from 4 nm to 5 µm and can be stored for months without breaking down. The next step is finding a metal that has a higher melting point, because many electronics generate heat that can melt the solder.

Waves may ripple across methane seas of Saturn’s moon Titan

7 March 2016
Ars Technica: Titan, Saturn’s largest moon, is the only other object besides Earth known to have stable bodies of liquid on its surface. Despite atmospheric temperatures averaging −180 °C, Titan is dotted with lakes filled with liquid methane and ethane. Using images captured by NASA’s Cassini spacecraft, scientists say they have been watching a transient island-like feature, which periodically brightens and dims, in the second largest of Titan’s lakes, Ligeia Mare. Probably caused by surface waves, the phenomenon is not an isolated one; other transient "islands" have been seen in another of Titan’s seas, Kraken Mare. Because of the apparent dynamic activity and the fact that Titan is full of organic molecules, Charles Elachi of NASA’s Jet Propulsion Laboratory says the moon could host “weird life” unlike anything we have seen.

Enigmatic cosmic source pumps out multiple radio bursts

7 March 2016
Previously observed examples of the pulses seemed to originate from cataclysmic, one-off events.

Water lily beetles fly while tethered to water’s surface

7 March 2016
New York Times: At least one pond-skimming insect has mastered the art of flight at the interface where air meets water. Rather than skate across the surface like a water strider or swim like a whirligig beetle, the water lily beetle attaches itself to the water's surface with its tarsal claws and flaps its wings to generate power and propel itself. The beetle uses that method of interfacial locomotion to zip between lily pads, its main food source. Manu Prakash of Stanford University and his colleagues used high-speed video and mathematical analysis to study the beetle’s movements and the physical forces involved. They found that despite its remarkable locomotive system, the beetle has no ability to brake—it simply skims the water until it crashes into the next lily pad.

Scalable five-qubit quantum computer performs Shor's algorithm

4 March 2016

IEEE Spectrum: In 1994, Peter Shor of MIT developed an algorithm for using a quantum computer to factor large numbers, a necessary step for decrypting data. Seven years later, Isaac Chuang of MIT and his colleagues created the first quantum system that could run Shor's algorithm, although their system could factor only the number 15. Now Chuang's team has developed a five-qubit system that can factor 15 and be scaled up to factor larger numbers. The researchers used a quantum computer prototype called an ion trap, in which a string of ions held in place by an electric field and manipulated by laser pulses serves as the qubits. As long as the trap can hold the ions in place, the number of qubits can be increased.