Physics Today Daily Edition

Subscribe to Physics Today Daily Edition feed
Please follow the links to view the content.
Updated: 4 hours 23 min ago

Climate change is affecting the speed of sound in the Arctic Ocean

9 August 2016
Nautilus: The speed of sound varies in water: The colder the temperature, the slower sound travels. The phenomenon is important for underwater communications, such as the sonar used by the US Navy. Since about 1975 ocean water flowing below the icy surface of the Beaufort Sea in the Arctic Ocean has been warming due to climate change. The result is a channel of warmer water called the Beaufort Lens, which stretches from Alaska to the Northwest Territories. Its multilayer structure allows sound to travel through it much farther and faster than expected. To get a better idea of the sound channel's acoustic properties, a team of scientists with the navy and MIT traveled there in March and dropped a 385 kg, 3.5 m drone through the ice. Another foray with a more precise and complex measurement system is already being planned for 2018.

Stratigraphic data pinpoint prehistoric Chinese flood

8 August 2016
BBC: According to legend, some four millennia ago China’s Emperor Yu tamed the so-called Great Flood on the Yellow River. After more than a decade of work to build canals and drain the water out to sea, Yu founded the Xia dynasty, which according to Chinese history was the first one. Until now the exact dates of the flood and the start of the Xia dynasty were unknown. By studying sediments washed about 25 km downriver to an abandoned prehistoric site called Lajia, Wu Qinglong of Nanjing Normal University and colleagues have managed to trace the legendary sequence of events. Lajia’s cave dwellings and cultural artifacts had been buried the year before the flood by a major earthquake, which the researchers say could have also caused a landslide farther upstream that dammed up the Yellow River. The bursting of that dam some six to nine months later created the cataclysmic flooding event. Because of Lajia, known as the Pompeii of China, the researchers have been able to determine that the flood occurred around 1922 BC, and hence that the Xia dynasty was founded around 1900 BC, which is 200–300 years later than had been previously thought.

Iranian nuclear scientist executed

8 August 2016
Guardian: Nuclear scientist Shahram Amiri was hanged in his home country of Iran last week. The Iranian judiciary had accused him of giving away state secrets. His activities in recent years had been "shrouded in mystery," writes Saeed Kamali Dehghan for the Guardian, starting with Amiri's disappearance in 2009 in Saudi Arabia while on a pilgrimage to Mecca. It was thought by some that he had defected to the US as part of an intelligence coup. Whether he returned willingly to Tehran in 2010 or whether he did so because his family had been threatened has not been determined. “Amiri was a victim of the nuclear standoff and its viciousness,” according to Ali Vaez, senior Iran analyst at the International Crisis Group.

Venus may have been habitable more than 1 billion years ago

8 August 2016

New Scientist: Venus is extremely hot, lacks liquid water, and has a toxic atmosphere. Yet a new simulation suggests that as recently as 1 billion to 2 billion years ago, the planet might have been habitable. David Grinspoon of the Planetary Science Institute in Tucson, Arizona, and his colleagues used a variation of a simulation of Earth's climate to create several possible models of the evolution of Venus's climate. The results suggest that an early Venus would have been quite similar to Earth at around the same time that life first evolved on our planet. However, a period of extreme volcanism 715 million years ago turned Venus into the searing planet it is today.

Sunflowers' sun tracking tied to circadian rhythms and varying growth rates

8 August 2016
NPR: Sunflowers are known for their ability to turn to follow the sun throughout the day. Now Stacey Harmer of the University of California, Davis, and her colleagues have determined the mechanism that allows the plants to do so. The researchers found that the circadian rhythm of plants is closely tied to the 24-hour day. The flowers start each morning facing east. During the day the stem grows primarily on the east side, twisting the flower's head toward the west. During the night, growth occurs on the other side, turning the flower back toward the east. Harmer's group found that plants that were restricted from moving grew significantly less than unbound plants. Plants exposed only to artificial light demonstrated the same 24-hour rotational pattern independent of whether the artificial light was on a 24- or 30-hour cycle.

South Pole experiment finds no sterile neutrinos

8 August 2016
However, the elusive neutrino flavor cannot be ruled out and remains an important theoretical building block.

Prospective particle disappears in new LHC data

5 August 2016
It’s back to the drawing board as hints of a 750 GeV particle vanish in this year’s run.

Desert sand could be used in thermal energy storage

5 August 2016
SciDev.Net: Typical concentrated solar power facilities use materials such as synthetic oil or molten salts to collect excess thermal energy and save it for later use. Now researchers at the Masdar Institute of Science and Technology in Abu Dhabi, United Arab Emirates, propose replacing those materials with something cheaper and more readily available in that area: sand. Modeled on an hourglass, the new system comprises two reservoirs connected vertically by a narrow passage. As cold sand grains in the upper reservoir drain to the lower one, they are heated by solar energy. The hot sand in the lower reservoir can then be used to power various devices, such as electricity-generating turbines. Once the sand grows cold, it is then returned to the upper reservoir and the cycle is repeated. The researchers next plan to scale up their prototype and seek industrial collaboration.

Hidden painting by Degas discovered with x-ray fluorescence

5 August 2016
New York Times: Beneath the painting Portrait of a Woman by French impressionist Edgar Degas lies another portrait that he had painted over—a common practice among artists of that era. That earlier portrait has now been revealed through the use of a type of particle accelerator called a synchrotron. Using the synchrotron’s intense x-ray beam, David Thurrowgood of the National Gallery of Victoria in Australia and colleagues scanned the painting and analyzed it point by point, looking for the chemical signatures of the various metallic elements used in the pigments of the paint. With those data, they were able to digitally reconstruct on a computer monitor the hidden portrait; the subject has turned out to be one of Degas’s favorite models, Emma Dobigny.

Australia reverses course on climate agency

4 August 2016

Nature: Six months ago, a reorganization of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) eliminated a large number of climate science positions. But today, science minister Greg Hunt announced that CSIRO would reprioritize basic climate science by creating 15 new jobs and would receive an additional Aus$37 million ($28 million) over the next 10 years. The change in policy comes in the wake of federal elections in July that nearly resulted in a hung parliament and forced Prime Minister Malcolm Turnbull to make concessions and alliances to maintain his seat. Many Australian climate researchers think that the about-face is too little, too late and that hiring 15 climate researchers won't offset the many more who still stand to lose their jobs.

China declares its lunar probe has stopped operating

4 August 2016

The Verge: This morning, China officially confirmed that its Yutu, or "jade rabbit," lunar rover is no longer operating. Launched in March 2013 as part of China's Chang'e 3 mission, Yutu proved to be the country's first successful lunar rover. Planned to last just 3 months, it instead held on for 31 months, becoming the longest-operating lunar rover. Communications with the rover were briefly lost in February 2014 after one of its shutdowns during the lunar night, a 14-day period in which temperatures drop as low as –183 °C. When communications were reestablished, it was confirmed that the rover had lost the ability to move, and Yutu has remained stationary ever since. Among the new information learned about the Moon, Yutu's instruments have revealed that there are nine distinct layers of rock beneath the lunar surface and that the rover's landing site differs geologically from the Apollo landing sites.

<em>Kepler</em> data reveal the exoplanets most likely to have liquid water

4 August 2016
Daily Mail: Among the 4000 new planets discovered by NASA’s Kepler space observatory, 216 are located close enough to their star to contain liquid water on their surface, and of those, 20 appear to be rocky like Earth, according to a new study published in the Astrophysical Journal. Stephen Kane of San Francisco State University and his colleagues say their study represents a “complete catalog of all of the Kepler discoveries that are in the habitable zone of their host stars.” Next the group plans to focus on the short list of Earth-like planets to see if any are actually habitable.

Unraveling the jet-lag asymmetry

4 August 2016
A new mathematical model could explain why a flight from Los Angeles to Paris leaves you groggier than the same trip in reverse.

North Korea plans advanced space program, including Moon launch

4 August 2016
Guardian: In an interview with the Associated Press, Hyon Kwang-il, director of the scientific research department of North Korea’s National Aerospace Development Administration, announced that the country is embarking on an ambitious five-year space program. The goal is to launch more Earth observation satellites, one of them a geostationary communications satellite. North Korea currently has two satellites in orbit. Within 10 years, Hyon says, the country plans to launch an unmanned Moon mission. Although concerns over the potential military applications of rocket launches have been raised, Hyon maintains that the satellites will be used solely for communications and to gather data on crops and other vegetation.

The latest version of OriginPro—a review

3 August 2016
A physics professor tries out the popular data analysis and plotting software for the first time.

US grants first commercial license for a lunar mission

3 August 2016

Ars Technica: Historically, Earth's orbit has been the limit for commercial activity, with an international treaty holding signatory nations responsible for the supervision of all commercial access and use of outer space. Now the US has granted Moon Express, one of the companies competing for Google's Lunar XPrize, approval to send a probe to the Moon, which the company intends to do in 2017. The company applied for the license in April 2015. The approval process, which has not been formalized, included reviews by the Federal Aviation Administration, the Department of State, NASA, and the White House, with input from the Department of Defense, the Federal Communications Commission, and the National Oceanic and Atmospheric Administration. A more formal system will likely need to be developed as other companies, such as SpaceX, are likely to pursue similar licensing.

Permissions rights complicate the use of large data sets

3 August 2016

Nature: Just because a data set has been made public doesn't mean that other researchers can use the data however they please. For example, University of Pennsylvania data scientist Daniel Himmelstein has set up Hetionet, an online resource based on 28 public data sets that shows the known connections between drugs, diseases, and genes . When creating it, Himmelstein contacted the researchers who published the data sets to get permission to reproduce the work publicly. Several never responded or replied in ways that didn't clarify whether he had been granted permission to publish. Generally a fact or a piece of data is not copyrightable, but the European Union and some countries treat data sets in a way that limits republication. In the US, where data sets are not directly protected, it is arguable that the compilation and organization of a data set's facts could have similar protections.

Io's atmosphere turns into frost in Jupiter's shadow

3 August 2016

Science: During its orbit of Jupiter every 42 hours, the moon Io takes about two hours to pass through the gas giant's shadow. In that time the temperature on the surface cools from –146 °C to –168 °C. Astronomers have used a ground-based IR telescope and observed that during that period roughly 80% of Io's primarily sulfur dioxide atmosphere turns to frost and settles onto the moon's surface. When Io moves out of Jupiter's shadow, the frost turns back into gas.

AMS report: 2015 set several climate records

3 August 2016

The Guardian: On 2 August the American Meteorological Society released its 26th annual State of the Climate report, which is compiled by the National Oceanic and Atmospheric Administration with input from hundreds of scientists around the world. The report indicates that 2015 saw record highs for atmospheric and oceanic temperatures, sea levels, and atmospheric carbon dioxide. The annual surface temperature increased 0.1 °C over 2014, and thus the global temperature is now 1 °C warmer than during preindustrial times. The eastern Pacific Ocean, which experienced further warming from El Niño, was 2 °C warmer than the long-term average, and the Arctic was 8 °C over its average. Oceanic warming contributed to a sea level that is about 70 mm higher than the average in 1993, when satellite measurements of sea levels began. The report also pointed to record lows for Arctic maximum sea-ice coverage and a net loss of alpine glacier ice for the 36th consecutive year.

Bad summer for the journal impact factor

2 August 2016
Scientific publishing observers and practitioners blast the JIF and call for improved metrics.