Physics Today’s online staff summarize the most important and interesting news about science from the world's top media outlets.
New Scientist: Pulsars are neutron stars whose rapid rotation forces beams of radiation from the poles. Over time, the rotation rate gradually slows, and the deceleration is dependent on the pulsar's age. Some older pulsars become intermittent, decelerating slowly while not emitting much radiation and then decelerating more quickly while emitting lots of radiation. Now, a relatively young pulsar has displayed the characteristic deceleration of those older pulsars. Frank Marshall of NASA's Goddard Space Flight Center in Greenbelt, Maryland, and his colleagues suggest that the star's magnetic field could be the cause. In intermittent pulsars, as the magnetic field shifts, it alternately traps plasma that releases radio waves and then releases it. Further observations are necessary to determine if the star is an intermittent pulsar, but studying it more closely is likely to provide more information about the behavior of pulsars in general.
Nature: Hydrogen sulfide, the colorless gas that smells of rotten eggs, has been coaxed into demonstrating a characteristic property of superconductivity at a record high temperature of 203 K (−70 °C). Last year, Mikhail Eremets of the Max Planck Institute for Chemistry in Mainz, Germany, and his colleagues had seen H2S superconducting below 190 K when compressed at 1.5 million atm. At such extreme pressures, the gas compresses into a solid crystal. Now, at a pressure of 2 million atm, the H2S exhibited a sudden increase in "magnetization signal" at 203 K. That increase occurs when the material prevents external magnetic fields from passing through it, a phenomenon known as the Meissner effect. Two other groups report that they have seen the same phenomenon but are waiting for Eremets's team to publish first. The previous highest superconducting transition temperature, 135 K, was obtained in 1993 in a layered cuprate material.
New Scientist: Over the years, ice and hydrocarbons have been spotted in interstellar space by telescopes pointed at the supermassive black hole in the Milky Way's center. Their presence was revealed by the absorption spectrum in the IR. It was assumed that they were located far from the galactic center, however, because the level of radiation near the central black hole is high enough to melt most ice and potentially destroy hydrocarbons. Now, Jihane Moultaka of the Research Institute in Astrophysics and Planetology in Toulouse, France, and her colleagues have revealed that some of that ice is quite close to the central black hole. To make that determination, they removed the signatures of ice and hydrocarbons from nearby regions of space. The leftover signals aligned with maps of galactic dust. Moultaka's team believes that the ice, which ranges in temperature from 10 K to 80 K, is sheltered by the dust particles. The presence of cold dust clouds suggests that stars can still form near the galactic center.
Science: Wind and water movement, tectonic activity, and other processes have continually eroded Earth's surface to a degree unseen on Mars or the Moon. As a result, there are far fewer impact craters visible on Earth's surface compared with the 300 000 on Mars and the uncountable millions on the Moon. In 2014, it was determined that all the craters on Earth with a diameter larger than 85 km had been discovered. Now, Stefan Hergarten and Thomas Kenkmann of the University of Freiburg, Germany, have extended that down to all craters larger than 6 km across. The determination that no more large craters will be found is based on impact and erosion rates, theoretical crater distribution, and the number of craters actually found. Hergarten and Kenkmann go on to suggest that only about 350 craters between 0.25 km and 6 km in size remain to be discovered.
Nature: On 14 July, NASA's New Horizons spacecraft is scheduled to make its first flyby of Pluto. Pluto's orbit has never been fully mapped because it hasn't completed an orbit since it was discovered. The fact that no one knows Pluto's exact location combined with the 9-hour communication lag between New Horizons and Earth means the craft will be essentially approaching the dwarf planet blind. During the flyby, the craft has to pass through a window of space just 100 km by 150 km. The targeted path is only 12 500 km above Pluto, and the spacecraft will be moving nearly 14 km/s. The last chance for mission navigators on Earth to signal New Horizons for a change of course will be 4 July. As the craft approaches Pluto, it is taking daily pictures of the planet, which allows the people guiding it to more accurately calculate Pluto's position against the background stars. But they still haven't been able to get an accurate measurement of the distance to the dwarf planet.
New York Times: To prevent signal degradation, current fiber-optic cables have to convert the signal from light to electricity and back to light roughly every 97 km . Now, Nikola Alic of the University of California, San Diego, and his colleagues have transmitted a fiber-optic signal 12 000 km without having to regenerate the light. In their paper, which does not cover that achievement, they explain that they used specially pulsed laser light to limit the amount of distortion that the light experiences within the cable as a result of a nonlinear response known as the Kerr effect. That allowed the team to increase the strength of the transmission lasers 20-fold. If the technique can be applied to real-world situations, it could drastically increase data transmission rates while also decreasing the costs of fiber-optic networks.
Science: On Monday, Jill Hruby was named Sandia National Laboratories' new director. Hruby will be the first woman to lead one of the US's three nuclear weapons labs. As the head of Sandia, Hruby will oversee much of the country's R&D focused on maintaining and upgrading the country's nuclear arsenal. Hruby, who has worked at Sandia for the last 32 years, will take over for Paul Hommert on 17 July. Sandia has a lower profile than its counterparts at Los Alamos National Laboratory and Lawrence Livermore National Laboratory, but is considered by the Department of Energy to be the best managed of the three facilities.
Daily Beast: Earlier this year, 47 galaxies with certain similarities were found in the Coma Cluster. They are all nearly as large as the Milky Way but have only as many stars as dwarf galaxies and almost no gas, which makes them hard to detect. Now, 854 more of these "ultra diffuse galaxies" (UDGs) have been found in the same area, near the heart of the Coma Cluster. Despite the galaxies' low density of stars and gas, their structures are similar to those of normal galaxies, which suggests they have an abundance of dark matter. However, until the galaxies' mass can be measured, that cannot be confirmed. Whether UDGs are present in all galaxy clusters or only in old, large ones like the Coma Cluster is still an open question as well.