Physics Today Daily Edition
Ars Technica: An Arizona court has rejected a lawsuit by the Energy & Environment Legal Institute, which sought to gain access to faculty emails at Arizona state universities. After examining sample emails, the court determined that the state's university system had correctly responded to the institute's open-records request. The institute had requested emails from a variety of university faculty members, including two climate researchers: Jonathan Overpeck and Malcolm Hughes. The university system's Board of Regents rejected the request because the emails were private, contained student information, and discussed ongoing research. The institute also lost a similar case in Virginia, which included the emails of climate researcher Michael Mann. The case marks the second time a court has ruled that materials detailing ongoing research projects are not subject to open-records requests.
Los Angeles Times: Mercury and the Moon are often compared because they are about the same size and both lack atmospheres. But Mercury is covered in dark material that makes it only one-third as reflective as the Moon. Most airless planetary bodies as dark as Mercury have a high iron content, but Messenger measured the planet’s surface as being just 2% iron. Now, Megan Bruck Syal of Lawrence Livermore National Laboratory and her colleagues believe they’ve found the explanation. They realized that the planet’s dark appearance could be caused by the presence of carbon-rich cometary dust, and their calculations of potential dust impacts revealed that the dust would stay on Mercury’s surface. They also determined that, because the concentration of cometary dust in the solar system is much greater closer to the Sun, Mercury gets hit by 50 times as much dust as the Moon, which explains why Mercury is so much darker. Finally, they found that firing cometary dust-like material at material similar to that found on Mercury’s surface did produce a dark layer on the surface material.
New Scientist: In 2012 researchers announced that they may have found a planet orbiting Alpha Centauri B. The finding was based on slight wobbles observed in the star's motion and suggested the planet orbited the star every three days. A subsequent set of observations in 2013 and 2014 by Brice-Oliver Demory of the University of Cambridge and his colleagues, who used the Hubble Space Telescope to look for a dimming of the star's light, revealed a single transit of Alpha Centauri B. However, the duration of the transit was longer than had been predicted for the planet. Demory's team ruled out other phenomena to explain the transit, which suggests the existence of a second planet in orbit around Alpha Centauri B. Confirming the second planet won't be easy because it would require 20 consecutive days of observations with Hubble. Given the many demands for time on the telescope, approval for such a long observation is unlikely.
BBC: Graphene, the single-atom-thick arrangement of carbon atoms with a wide range of curious properties, was first isolated at the University of Manchester in the UK in 2004. Now, researchers from the university have contributed to the design of the first commercial consumer product to use graphene: a light bulb with a graphene-coated filament. The increased conductivity of the graphene reduces the bulb's energy use by 10% and lengthens the bulb's lifetime. The bulbs are expected to be available for sale later this year for under £15 ($22), which is less expensive than current LED bulbs.
New York Times: Coal still supplies two-thirds of China's power generation, but with the nation's economy growing at the slowest rate in 25 years and a mandated shift to nuclear and renewable sources, coal imports and utilization have dropped significantly over the last year. In 2014 the use of fossil fuels to generate power was at a record low of 53.7%, down from 57.3% in 2013. That reduction led to a drop of 18 million tons or 1.3% in the amount of coal used and to a 11% reduction in coal imports by the world's largest coal consumer. The trend is expected to continue through 2015. As a result, the cost of coal from Australia, one of China's primary sources, fell 30% last year to under $60 per ton this month, the lowest since May 2007.
BBC: Observations of 72 galactic collisions have revealed to a higher level of detail than ever before that dark matter is unaffected by any force other than gravity. Richard Massey of Durham University in the UK and his colleagues used Hubble Space Telescope and Chandra X-ray Observatory to observe the collisions in both visible and x-ray light. The x-ray images revealed the movement of the clouds of plasma that reside inside and around galaxies whereas the visible images showed the movements of the stars. The combined images allowed the researchers to measure the gravitational lensing effect of the dark matter. The observations revealed that the dark matter exhibited no sign of non-gravitational interactions with itself or other matter to a much higher level of precision than previous observations.
Los Angeles Times: In the early 1980s the Voyager spacecraft measured the length of Saturn's day to be 10.6 hours based on the planet's magnetic field. But when Cassini reached the planet in 2004, it obtained a different result. Subsequent measurements revealed that the planet's magnetic field, unlike Earth's, is aligned with the axis of rotation; it cannot, therefore, be used for an accurate measurement. Other techniques that attempted to use the planet's wind patterns proved even less accurate. Ravit Helled of Tel Aviv University and his colleagues have now used Saturn's gravitational field to measure the length of the day, which they found to be 6 minutes shorter than the original Voyager measurement. The technique uses the periodic changes in pull that Cassini feels as Saturn rotates as well as measurements of the planet's oblateness. The researchers confirmed the accuracy of the technique by testing it against Jupiter, whose day has a well-known length.
Nature: The oxygen atom in a water molecule is tightly bound to the two hydrogen atoms, but it also experiences a slight connection with the hydrogen in neighboring molecules. Because of this, as water freezes, the molecules arrange themselves into three dimensional tetrahedral shapes. Now, Andre Geim of the University of Manchester, UK and his colleagues have discovered that water pressed between sheets of graphene freezes into an ice in which the molecules form two-dimensional layers of square shapes. The structure could be the 18th different type of water ice discovered. Geim's team calculated that the pressure exerted on the water by the graphene sheets exceeds 10 000 atm or 1 gigapascal.