Physics Today Daily Edition
Ars Technica: The weathering of minerals on Earth’s surface helps regulate its climate over geological time scales. As the minerals break down, they react with carbon dioxide. In warmer regions, the minerals break down more quickly, resulting in more CO2 being sequestered, which has a cooling effect. In cooler regions, the minerals break down more slowly and less CO2 is sequestered, which has a warming effect. Other factors are known to contribute to such physical weathering, including the breaking up of rocks and soil by tree roots, lichens and fungi, and burrowing organisms. To try and determine to what degree biology influences the process, Ronald Dorn of Arizona State University conducted a 25-year-long study of the weathering of basalt sand samples placed in a variety of environments, from Arizona to Texas. He put the samples in holes augured into the ground, tree roots, ant nests, and other locations. When he compared the samples, the material in the ant nests showed the most weathering, with 50–175 times that of the baseline sand. How the ants cause such accelerated weathering is unknown, but understanding the chemistry involved might one day help humans in their efforts to reduce atmospheric carbon levels.
Guardian: China has suffered a number of food scandals in recent years—from toxic milk to glow-in-the-dark pork to recycled cooking oil. To determine whether food is safe to eat, a set of “smart” chopsticks has been developed. When linked with a smartphone app, they can indicate the levels of freshness, contamination, and nutrition of the food they touch. The product is the brainchild of Baidu, the Chinese version of the search-engine giant Google. Although the chopsticks were demonstrated at the company’s recent technology innovation conference in Beijing, they are not yet ready for mass production.
Nature: Because of the hint of an impending El Niño in January, researchers are watching the Pacific Ocean closely for any changes in temperature and atmospheric conditions. Extreme El Niño events, such as those that occurred in 1982–83 and 1997–98, can severely disrupt global weather patterns. The 1997 event, one of the strongest on record, “caused extreme rainfall along the western coasts of North and South America and drought in Australia and southeast Asia, resulting in thousands of deaths and tens of billions of dollars’ worth of damage,” writes Mark Zastrow for Nature. For that reason, scientists are using satellites, buoys, and autonomous underwater vehicles to gather as much information as possible on the impending event. Not only do they hope to be able to improve their forecasting of future El Niño events, but they also want to better understand El Niño’s history going back thousands of years.
Japan Times: Last weekend the Japanese Aerospace Exploration Agency (JAXA) revealed its Hayabusa 2 spacecraft. As the name suggests, it is a follow-up to JAXA's Hayabusa, which returned to Earth in 2010 after completing a seven-year mission to collect samples from the asteroid Itokawa. Hayabusa 2 will target asteroid 1999 JU3, which contains both carbon and water. JAXA hopes that the samples it collects will provide clues to the origin of life and the formation of the solar system. The agency plans to launch the spacecraft later this year.
Ars Technica: Phase-change materials take on different physical structures depending on the speed at which they are cooled. They are amorphous with a high electrical resistance when quickly cooled, and regular with low resistance when slowly cooled. The materials have been used to create computer memory bits, and last year they were combined with resistors to form logic gates. Now a group of researchers has created a single phase-change memory bit that can act as multiple logic gates. To do that, they provide a low level of heating to the hardware, which makes flipping the bit easier. Then they use pulses of low heat and high heat, representing 0 and 1 respectively, to affect how the bit functions. A single pulse causes the bit to behave as an OR gate, and combinations of pulses can cause it to behave as a NOR or NAND. The low-level heating increased the speed at which the bit switches states to nearly the same speed as modern processors. It is not yet clear whether having a single bit perform multiple gate functions will be useful, but the development is an important proof-of-concept step for phase-change materials in computing.
BBC: Many of the world’s languages are disappearing, particularly in regions with high economic growth, according to a recent paper published in the Proceedings of the Royal Society B. Environmental factors have long played a role in shaping language diversity. However, now it seems that because of accelerating economic development in certain parts of the world, minority languages are giving way and a single, national language is taking over. Tatsuya Amano of the University of Cambridge and colleagues say most at risk are minority languages in North America, Europe, and Australia. The tropics and the Himalayas, home to many small-population languages, may also face similar problems as rapid economic growth commences in those areas. The researchers hope to call attention to the phenomenon in order to better promote and direct efforts to prevent this cultural loss.
Los Angeles Times: The US Environmental Protection Agency is proposing to reduce the federal standard for ground-level ozone. The EPA is required by the Clean Air Act to review the standard every five years. California, which has 16 areas that don’t meet the current ozone limit, will be particularly hard pressed if it is lowered. "We're going to need to have zero or near-zero emissions across the entire economy,” said Sam Atwood, a spokesman for the South Coast Air Quality Management District. Although industry representatives and Republican members of Congress insist that lowering the environmental limit will damage the economy, Janice Nolen, assistant vice president of national policy at the American Lung Association, claims just the opposite: “Since the 1970s, we've reduced major air pollutants by 70% and the economy has more than doubled."
New Scientist: According to a recent paper published in Precambrian Research, both the average rate of continental collisions and the average speed with which the continents change latitude have doubled over the past 2 billion years. Kent Condie of the New Mexico Institute of Mining and Technology and colleagues based their findings on two sets of data: the timing and locations of mountain-range formation and average plate velocities based on magnetic data from volcanic rocks. The researchers think the acceleration may be due to the amount of water in Earth’s mantle, which has recently been found to be much vaster than previously thought. As a result, the mantle may becoming runnier, which could speed up the rock flow. However, the work is considered controversial because it contradicts a previous study that says plate motion has been slowing for the past 1.2 billion years due to the cooling of Earth’s core and mantle.
BBC: Type Ia supernovae have long been thought to be caused when a white dwarf gains enough mass to push it over the Chandrasekhar limit. White dwarfs are the remains of stars that have burned through most of their light elements and have a core of carbon and oxygen that is no longer undergoing fusion. If they steal enough material from a companion star, or merge with another white dwarf, the extra mass compresses the core and causes the heavier elements there to fuse. The sudden release of energy causes the star to explode into a supernova. Although the theory has been widely accepted for decades, a supernova detected on 21 January 2014 has provided the first confirmation that a white dwarf is the source of type Ia supernovae. When a white dwarf’s carbon and oxygen fuse, they create a radioactive isotope of nickel that decays into radioactive cobalt that then decays to stable iron. Observations of the supernova using the European Space Agency’s INTEGRAL spacecraft revealed the signature gamma-ray emissions associated with the cobalt isotope’s decay. The emissions also closely matched the model of a white dwarf explosion. However, there is still not enough information to determine whether it was a white dwarf drawing material from a companion or a collision of two white dwarfs that caused the supernova.
New Scientist: To probe space and time at the very smallest scales, researchers at Fermilab have built a holographic interferometer, or holometer. At the quantum level, matter and energy behave more like waves than particles. The researchers propose that a similar concept may apply to space and time. Their device consists of two 40-meter-long tubes fitted with mirrors through which they shine powerful lasers. If both sets of mirrors are seen to change position as much as a billionth of a billionth of a meter, it could indicate the existence of fluctuations in the fabric of space. If such a spacetime jitter exists, it would present another explanation of why the universe is accelerating besides the current one involving dark energy.