Physics Today Daily Edition
Ars Technica: A recent NASA document hints that the agency is frustrated with the progress of Orion, the crew-carrying spacecraft under development with primary contractor Lockheed Martin. In September NASA issued a Request for Information (RFI) to extend the contract for Orion capsules beyond Exploration Mission-2, the first crewed flight, which is scheduled for the early 2020s. The RFI also appears to open the door for a competitor to step in, either to replace Orion with another capsule or to take over construction of future capsules. NASA may have chosen that approach because of dissatisfaction over the delays and cost increases for Orion. Only one uncrewed launch has taken place—in 2014, the original target year for the first crewed launch. At the very least, the RFI appears designed to force Lockheed Martin to lower its bid for building future Orion capsules. The timing of the RFI also suggests that NASA wants more options going forward because the new presidential administration might have different priorities.
Science: Located at Sandia National Laboratories in Albuquerque, New Mexico, the Z machine is an experimental fusion reactor that eschews the toroidal containment walls of tokamak reactors. The system compresses a pencil eraser–sized fuel container with a blast of electricity to initiate the fusion reaction. Until August, tests with the Z machine had used pure deuterium as the fuel. But since then researchers have been adding tritium to the mix, and over the next five years they will ramp up the proportions to reach a 50–50 blend. That balance produces 60 to 90 times as many neutrons as the deuterium-only fuel and more than four times as much energy. The hope is that the machine can exceed the fusion power record of 16 MW set by the Joint European Torus tokamak in 1997. Using tritium is difficult because it is expensive, mildly radioactive, and combines with water to become significantly more hazardous. But the researchers at Sandia believe that moving forward with the substance is necessary to achieve viable fusion systems.
Nature: Before the US presidential election, the majority of major national polls suggested that Hillary Clinton would win the presidency by a 3–4% margin in the popular vote. Poll aggregators, which apply algorithms to national and state polling numbers to attempt to paint a clearer picture of the outcome, predicted a 71% or better chance of a Clinton victory. Obviously, that did not happen. Clinton ended up, as of 10 November, with a popular vote lead of only around 0.2%, and she lost to Donald Trump in several states she was expected to win. Claudia Deane of Pew Research Center in Washington, DC, says the surprising thing is that so many polls with such a wide range of methodologies all erred in the same direction. Some potential factors contributing to the widespread polling failure include poor assessments of likely voters, people misrepresenting their voting intentions, and poor coverage of certain segments of the voting population. Some of those problems are likely rooted in the shift away from landlines to cell phones, as many people do not respond to unknown phone numbers. Meanwhile, online pollsters often have difficulty obtaining a statistically useful distribution of respondents.
Science News: Two teams of researchers have announced the creation of supersolids—matter that has a crystalline structure like a solid but can flow without friction like a superfluid. Both teams, one at MIT and the other at ETH Zürich, used the same general technique to produce the supersolids within Bose–Einstein condensates (BECs). Because a BEC is already a superfluid, the teams sought to create regular density variations within the material so it would also behave like a solid. Using lasers to push some of the atoms in the BEC, the MIT group created an interference pattern that resulted in alternating high- and low-density regions in the material. The ETH Zürich group created a similar regular pattern by placing a BEC inside two optical cavities in which light repeatedly bounces back and forth between sets of mirrors. Verification of either team's result would be the first confirmed identification of a supersolid.
New York Times: Of all the rocky planets in our solar system, Earth is the only one with a large moon. Although most researchers agree that Earth’s moon probably formed when a Mars-sized object called Theia collided with Earth, modeling has failed to completely explain the Earth–Moon relationship as it exists today. Sarah Stewart of the University of California, Davis, and Matija Cuk of the SETI Institute say that by altering the impactor’s energy and momentum, they have come up with a sequence that better explains the current dynamics and compositions of Earth and the Moon. Further, the researchers' model also offers an explanation as to why the Moon’s orbit has a five-degree tilt relative to those of the planets and other objects in the solar system. Stewart and Cuk propose that when Theia struck Earth, it knocked Earth over on its side at an angle of 60–80 degrees. Over the next 4 billion years, Earth straightened up, but the Moon is still shifting.
Nature: Several thousand Nature readers responded to poll questions accompanying a piece about the frustrations that face young researchers, such as the growing pressures to publish, get funding, and find permanent positions. The poll found that 65% of nearly 9000 responding researchers had considered quitting research and that 15% had actually done so. More than a quarter of respondents said the challenges they face resulted in the publication of a paper they weren't proud of, and 16% said they had cut corners in their research for the same reason. Nearly 40% of the respondents worked more than 60 hours per week. The poll also revealed that 44% of researchers consider "the fight for funding" to be the biggest challenge facing early-career scientists. "Lack of work–life balance" and "progression judged too heavily on publication record" tied for the second most common response.
CNN: In December 2017, a hydrogen-powered train will begin transporting passengers along a 96 km route in northern Germany. The train is produced by the French company Alstom. Four German states have signed an agreement with the company to purchase up to 60 additional trains if the initial train, called the Coradia iLint, is successful. The train was unveiled by Alstom earlier this year as a replacement for diesel trains that run along nonelectric rail lines throughout Europe. The two-car train, which carries up to 300 passengers, runs silently and is powered by batteries that are charged from the combination of hydrogen, which is stored in fuel cells, and oxygen, which is obtained from the air around the train. Its tank holds 94 kg of hydrogen, enough to power the train over 800 km, or for about a day. The train is much slower than many of Europe's high-speed electric trains but is intended as a replacement for the shorter and slower sections of the European rail network.
IEEE Spectrum: Neurons use a chemical signaling process that is exceptionally quick, which allows neurotransmitters to be passed between cells in as little as 10 ms. Now, Daniel Simon of Linköping University in Sweden and his colleagues have created an organic electronic ion pump that uses electric fields to move charged particles across a thin film almost as quickly as neuron transmissions. The pump is 2.5 cm long and was created using photolithography to layer metal and polymer channels onto glass. Electrical currents push charged particle neurotransmitters along six paths. Flipping a switch applies a second electric field to a specific path, which causes the charged particles to shoot through an outlet and on to their destination. In tests with acetylcholine, the scientists were able to get the neurotransmitter to its destination in less than 50 ms.