Physics Today Daily Edition

Subscribe to Physics Today Daily Edition feed
Please follow the links to view the content.
Updated: 2 days 17 hours ago

Science-related excerpts from President Obama's State of the Union address

21 January 2015
It includes strong words on combating human-caused climate disruption.

Senators hope to amend Keystone XL bill with statement on climate change

21 January 2015
Science: The first bill under discussion by the Senate in the 114th Congress concerns the construction of the Keystone XL pipeline, which would bring oil from Canada to the US. The controversial bill is supported by the new Republican majority. Those senators who oppose it say the pipeline will exacerbate global warming and are pushing for amendments affirming that climate change is happening, that human activity is driving it, and that Congress should take action to address the issue. The goal of the amendments, says Charles Schumer (D-NY), is to put climate-change-denying senators in an awkward position. If they block the amendments, they could be accused of dodging the issue. If they let the amendments go to a vote, they will be forced to take an actual position on climate change, which could damage their standing with their constituencies.

Micromotors deliver therapeutic materials to mouse’s stomach

21 January 2015
BBC: For the first time, powerful microscale motors have been tested in a living organism. Researchers at the University of California, San Diego, report in the journal ACS Nano that they successfully inserted artificial micromotors, consisting of zinc-coated polymer tubes just 20 μm long, into the stomach of a mouse. The zinc reacted with the stomach acid and produced hydrogen bubbles that propelled the tiny machines into the stomach lining. As the machines dissolved, they released their cargo. The researchers believe that such artificial micromotors, which convert energy into movement, could deliver drugs much more effectively than conventional medicines, which rely on passive diffusion. The method could one day be used to treat peptic ulcers and other illnesses.

LHC restart and new underground experiment may be last chance for WIMPs

21 January 2015
Nature: Weakly interacting massive particles (WIMPs) are one explanation for the composition of dark matter, the invisible material that makes up 85% of the universe's mass. However, in the past few years several experiments have failed to detect any WIMPs. Although the Large Hadron Collider (LHC) at CERN was thought capable of creating the particles during its previous run at 8 TeV, it did not. The most sensitive direct detection experiment yet, the Large Underground Xenon (LUX) project, also failed to find any candidate events during its first run in 2013. It's possible that the existence of WIMPs could be ruled out soon if neither the LHC, with an upgraded target collision energy of 14 TeV, nor XENON1T, a direct detection experiment 50 times as sensitive as LUX, finds any. If so, that would open the door to other possible dark-matter explanations that had been considered more "exotic" than WIMPs.

X-ray imaging reveals ancient writing on charred papyrus scrolls

21 January 2015
Los Angeles Times: In AD 79 when Mount Vesuvius erupted, it destroyed several ancient Roman towns, including Herculaneum, which had a extensive library. The blast of heat from the volcano carbonized, but did not completely destroy, the library's hundreds of handwritten papyrus scrolls. Discovered almost 300 years ago, the papyri are too damaged and fragile to be unrolled and read, although several attempts have been made. Because the ink used was carbon based, it has proven almost impossible to distinguish between it and the baked paper, even with such sophisticated techniques as x-ray computed tomography. Now Vito Mocella of the Institute for Microelectronics and Microsystems in Naples, Italy, and colleagues have tried a different technique, x-ray phase-contrast tomography, with which they have been able to make out a few words and letters by differentiating among phase shifts in the x-ray light as it passes through the different materials. The researchers hope the technique will open up new opportunities to read other ancient papyri and learn more about ancient Greek literature and philosophy.

Earthquakes shown to release some greenhouse gases

20 January 2015

Science: Tetrafluoromethane (CF4) is a greenhouse gas that persists in the atmosphere for 50 000 to 100 000 years. It is commonly produced by the weathering of granite and other metamorphic rocks by rainfall. Now Daniel Deeds of the US Geological Survey and his colleagues have discovered that CF4 is also produced by tectonic activity. Surprised to find the chemical in groundwater samples collected near an active fault in the Mojave Desert, the researchers then examined 14 samples taken from aquifers along part of the San Andreas Fault. All but one of the samples showed higher CF4 levels than did water that had been exposed to the air. That suggested the gas was being absorbed from stone deep underground. The researchers also found that the samples from closer to the fault had higher concentrations of the gas than did those from farther away. Whether the CF4 is produced by the fracturing of rocks during earthquakes or by pressure stresses is not clear. However, the discovery that CF4 levels are not exclusively tied to weathering means they are no longer a reliable indicator of past changes in climate.

Artificial heart recipient able to return home

20 January 2015
New York Times: An artificial heart manufactured by French company Carmat has been successfully implanted in a second human patient. Created by French surgeon Alain Carpentier, the device was first used in 2013 when it was implanted in a terminally ill 76-year-old man, who survived for 74 days. The second patient, a 68-year-old man, underwent surgery in August 2014 and is now doing so well that he has been released from the hospital and sent home. The device is made from both synthetic materials and animal tissues and requires an external battery pack. Because there are so many more people needing heart transplants than there are available organs, the artificial heart could extend the lives of those who are diagnosed with heart failure and have no other options.

Charles L. Opitz

20 January 2015

Geysers on Europa called into question

19 December 2014
New Scientist: Despite the detection by the Hubble Space Telescope last year of 200-km-high water jets erupting from the surface of Jupiter’s moon Europa, no evidence of such a geyser has been seen since. Donald Shemansky, of the University of Southern California, reported the finding at the American Geophysical Union conference in San Francisco on 18 December. Furthermore, data from NASA’s Cassini spacecraft, which flew by Jupiter in 2001, have failed to confirm the existence of the watery plumes. Either a mistake was made or the phenomenon is very rare, says Robert Pappalardo of NASA’s Jet Propulsion Laboratory in Pasadena, California.

Revamped <em>Kepler</em> spacecraft finds another exoplanet

19 December 2014
Ars Technica: Since its launch by NASA in 2009, the Kepler spacecraft has found more than 4000 planet candidates. Although crippled in 2013 by the failure of two of its four reaction wheels, Kepler has been returned to active duty by NASA scientists, who found a way to use the craft’s solar panels to point it in the right direction. Now Kepler has been able to continue its original mission of discovering Earth-like planets orbiting other stars. Although the new data are not as precise, Andrew Vanderburg of the Harvard–Smithsonian Center for Astrophysics and colleagues were able to spot yet another planet, HIP 116454b, which is 2.5 times the diameter of Earth and orbits a star that is smaller and cooler than the Sun.

NASA satellite begins to map CO<sub>2</sub> levels in Earth’s atmosphere

19 December 2014
Nature: Earlier this year NASA launched the Orbiting Carbon Observatory-2 to monitor carbon dioxide levels in Earth’s atmosphere. Although a design flaw was detected soon after launch, the problem was quickly rectified, and the satellite is now returning data on the sources and sinks of CO2. The data will allow researchers to better understand the effects of both human activities and natural systems. Through the burning of forests and fossil fuels, humans are sending some 40 billion tons of CO2 into the atmosphere, as evidenced by the high concentrations of the gas that have been detected over Africa, Australia, Brazil, China, Europe, and North America. About half remains in the atmosphere and half is absorbed by the oceans and land-based vegetation. How long the pollution will continue to be absorbed by those systems is one of the questions the satellite mission was designed to answer.

Popularizing condensed-matter physics

19 December 2014
Even when it lacks technological applications, the basic science of materials can be made appealing to nonspecialists.

Birds evacuate nesting area ahead of tornado

19 December 2014
BBC: In May 2013 Henry Streby of the University of California, Berkeley, and colleagues tagged 20 golden-winged warblers in order to monitor their seasonal 5000-km migration between Colombia and the US. The birds had just completed their journey to the Appalachian Mountains in April 2014 when their geolocators showed them taking flight once more on 26 April—one day before a series of tornadoes struck the central and southern parts of the US. Over the next five-day period, they flew a total of some 1500 km to the Gulf of Mexico and back. The researchers propose that the unexpected journey was made to avoid the severe weather, which the birds were able to anticipate because of their ability to hear the deep rumble tornadoes emit in the infrasound range. Sound in that range can travel thousands of kilometers, but it is below what humans can hear. In their paper published in Current Biology, the researchers conclude that as global warming causes ever more severe weather events, such behavioral responses of animals could be well worth studying.

<em>Washington Post</em>: “NASA’s $349 million monument to its drift”

18 December 2014
Is decline symbolized in a hugely expensive relic of the canceled Constellation lunar-return program?

Questions and answers with A. Douglas Stone

18 December 2014
In many ways, Albert Einstein undermined the seminal role he played in the development of quantum mechanics. Stone aims to set the record straight in his award-winning book.

Water discovered deep in Earth’s crust may harbor life

18 December 2014
BBC: Some of the oldest water on Earth has been discovered about 2.4 km below Earth’s surface, in a deep mine in Canada. Thought to be between 1 billion and 2.5 billion years old, the water appears to be reacting with the surrounding rock to produce hydrogen, a potential food source for living organisms. Not only was the age of the water surprising but also the fact that there is so much of it—more than all the world’s rivers, swamps, and lakes combined, according to a study published in Nature. As a result, global hydrogen production in the continental crust may be much higher than previously estimated. "It gives us a quantum change in our understanding of how much of the Earth's crust might indeed be habitable and have enough energy to sustain subsurface life,” said Barbara Sherwood Lollar of the University of Toronto in Canada, one of the authors of the study.

Mangrove forests may help protect against tsunamis

18 December 2014

New Scientist: Following the 2004 tsunami in the Indian Ocean, several studies examined satellite data to determine the ability of mangrove forests to protect communities from the destructive effects of such seismic sea waves. One study found an 8% reduction in fatalities in villages protected by mangrove forests. Another found that a 100-m-wide band of dense mangrove growth could reduce the strength of a tsunami by up to 90%. In the years since the tsunami, several groups have worked to restore and expand mangrove forests along shorelines of countries bordering the Indian Ocean. The most successful appears to be the Green Coast project run by Oxfam Novib and Wetlands International. The organizations planted mangroves in the Indonesian province of Aceh and provided loans to residents to establish new businesses in their villages. The villages were left in charge of maintaining the new mangrove trees. If 75% of the trees were still growing after 2 years, the loan debts were written off. Almost 2 million trees were planted near 70 villages, and five years after the end of the project most of the businesses are still operating.

US–Cuba accord holds promise for science

18 December 2014
Science: Yesterday President Obama and Cuban president Raúl Castro reached a landmark agreement to restore diplomatic relations between their two countries. For the past half-century, the US has imposed economic sanctions and a trade embargo on Cuba to punish the communist regime set up by Fidel Castro. The recent accord bodes well for the scientific community, according to Alan Leshner, CEO of the American Association for the Advancement of Science. The new policy could boost collaboration between scientists in the two countries, allow US groups to organize workshops and meetings in Cuba, and support the export of scientific equipment to Cuba to pursue certain areas of research, such as the study of hurricanes in the Gulf of Mexico. However, the agreement is expected to meet with opposition in the US Congress.

Airline pilot UV radiation exposure measured

18 December 2014

Telegraph: A study earlier this year revealed a higher rate of skin cancer in pilots than in the general population. A new study by Martina Sanlorenzo of the University of California, San Francisco, and her colleagues shows that every 56 minutes that airline pilots spend at a normal cruising altitude of 30 000 ft (9144 m) exposes them to as much UV radiation as a 20-minute session in an average tanning bed. They measured UV-A exposure at ground level and in cockpits during flights to Los Vegas, Nevada, in April 2014. For every 2952 ft (900 m) of altitude gained above sea level, the radiation exposure increased by 15%. At the typical cruising altitude for commercial aircraft, UV levels were more than twice those on the ground.

The heat is on for concentrated emulsions

18 December 2014
To understand the propagation of a sound wave through a scattering medium, it’s necessary to consider the conversion of energy from acoustic to thermal and back again.

Pages