Physics Today Daily Edition
The Guardian: On 26 May, President Obama became the first sitting US president to visit Hiroshima, Japan. Obama attended a ceremony at the bombing memorial, where he gave a speech about continuing efforts for nuclear disarmament and nonproliferation. "Technological progress without an equivalent progress in human institutions can doom us," he said. "The scientific revolution that led to the splitting of an atom requires a moral revolution as well." Obama also met survivors of the attack, which killed 140 000 people.
New York Times: Earlier this month, the US Department of Defense released its annual census of the nation's nuclear arsenal through the end of the 2015 fiscal year. At that point, the US possessed 4571 warheads, down 109 from the previous year and down 702 since 2008, the last year of President George W. Bush's term in office. The disarming of 109 warheads was the lowest annual rate of disarmament during President Obama's tenure, and the total reduction since 2008 accounted for just 13.3% of the stockpile, the smallest reduction by any administration since the end of the Cold War. According to Hans M. Kristensen of the Federation of American Scientists, the slower rate of disarmament is the result of various factors. Congress has opposed much of Obama's disarmament efforts, and Russia has rejected additional cuts beyond those agreed to in the 2010 New Start treaty. There is also a potential effect from the three-decade arsenal modernization effort that Obama initiated at an estimated cost of $1 trillion.
Science: On Monday, the US House of Representatives appropriations committee presented its first draft of the 2017 budget. Accompanying the budget was a report from the committee subpanel that oversees NASA. In the report, the subpanel calls for NASA to produce a technology assessment and conceptual road map within a year for an interstellar probe capable of reaching 10% of the speed of light. The report comes in the wake of the Breakthrough Starshot project, which proposes to use concentrated laser light to send tiny probes to other stars. The report does not say where funding for the NASA project will come from.
Ars Technica: At 39 m in diameter, the planned European Extremely Large Telescope (EELT) would dwarf all other telescopes, current and in the works. The European Southern Observatory, a partnership of European nations with Chile and Brazil, has now signed a contract for $450 million that it says will keep the EELT on schedule to begin operations in 2024. Like the 24.5-m Giant Magellan Telescope that is under construction, the EELT will be built on a mountaintop in Chile. Its final cost is expected to exceed $1 billion.
USA Today: On 19 May, during a presentation to award the National Medals of Science and Technology, President Obama announced that he was establishing a campaign for children to submit ideas about the future of science, discovery, and exploration in the US. The White House has set up a page on its website with a form for idea submissions. The campaign was prompted at the White House Science Fair in April, when nine-year-old Jacob Leggette asked Obama if he had any advisers who were kids.
Science News: Last year astronomers observed a burst of light—tagged ASASSN-15lh—from 3 billion light-years away that they reported as the brightest supernova ever seen. With a peak luminosity of around 550 billion times that of the Sun, the supernova was twice as bright as the previous record holder. Now Peter Brown of Texas A&M University in College Station and his colleagues say that ASASSN-15lh might not be a supernova. About 80 days after ASASSN-15lh peaked in brightness and began fading away, Brown's team saw it get brighter again. After another 80 days, the object was emitting as much UV light as some supernovae. An increase in brightness of supernova remnants can be caused by various known mechanisms, but none of the spectral absorption lines characteristic of those explanations have been found. Instead, Brown's team suggests that ASASSN-15lh is actually a star being swallowed by the supermassive black hole at the center of the source galaxy. The flash was emitted from near the galaxy's center, and the increase in brightness could stem from a second piece of the star falling into the black hole.
IEEE Spectrum: In 2015 China invested $102.9 billion in wind and solar power and ended the year with almost twice the installed wind capacity as the US. However, China generated less wind energy for the year than the US did. Michael McEvoy of Harvard University and Xi Lu of Tsinghua University and their colleagues suggest that the gap in production is roughly equally distributed between delays in connecting wind farms to the larger grid, low-quality equipment, and intentional favoring of coal power over wind by grid operators. The researchers offer the caveat that their data are from 2012. Both grid connection and wind farm technology have improved since then, which suggests that the favoring of coal plants is the primary cause of last year's production shortfall.
Ars Technica: A draft of the US House of Representatives' fiscal year 2017 budget released on 23 May alters NASA's direct-to-Mars plan by replacing visits to asteroids with expeditions to the Moon. The revised plan includes the development of habitation modules, prospecting techniques, and landing and ascent vehicles. The budget, which will be formally presented on 24 May, has to pass through the Appropriations Committee and the full House. If passed, the budget would have to be reconciled with the Senate's budget, which does not explicitly call for lunar landings. NASA's Journey to Mars program, developed following a 2010 speech by President Obama in which he called for crewed missions to Mars, has faced criticisms ranging from lack of realistic plans to an unwillingness by NASA to formalize a budget.
Science News: Astronomers study young Sun-like stars to learn what our solar system might have been like early in Earth's existence. According to Vladimir Airapetian of NASA's Goddard Space Flight Center in Greenbelt, Maryland, and his colleagues, those stars are significantly more active than the present Sun. The researchers estimate that 4 billion years ago Earth could have been struck by large solar flares at least once per day. If that's true, then the radiation could have triggered chemical reactions that produced nitrous oxide, a greenhouse gas, and hydrogen cyanide, a building block of DNA. That could help explain the development of life on Earth, the earliest traces of which are around 4 billion years old. At that time, the Sun had 70–75% of its current brightness, so the presence of greenhouse gases was necessary to keep temperatures on Earth above freezing.
BBC: On Monday, the North Yorkshire County Council approved a bid by Third Energy to establish a shale-gas fracking facility. The decision followed two days of hearings, with input from local homeowners, farmers, and Third Energy employees. The council decided to follow a planning committee's recommendation for approval despite just 36 favorable public comments out of the 4420 submitted. Fracking was banned throughout the UK in 2011 following tests that revealed the potential for earthquakes. Two other projects proposed since the reversal of the ban in 2012 have not received approval. The Third Energy project would use an existing 3000-meter-deep well that was drilled in 2013. The site would be fitted with seismic monitors that would automatically halt work in the event of a magnitude 0.5 quake.
Nature: Much of the pay gap between men and women with PhDs comes about because women tend to pursue degrees in less lucrative fields, a new analysis has found. But even after controlling for field of study, women still earned an average of 11% less than men in their first year. That difference emerged because married women with children earned significantly less than their counterparts. Unmarried, childless women earned the same annual salary as men with a PhD in the same field. The analysis, by Bruce Weinberg of the Ohio State University in Columbus and his colleagues, examined about 1200 graduates of PhD programs in the US. The analysis did not identify any specific factors explaining why married women with children earn less than their colleagues.
New York Times: Donald Trump's comments about climate change and energy policy, until now mostly restricted to Twitter, suggest he does not accept global warming. A briefing prepared by Representative Kevin Cramer (R-ND) for Trump has provided a bit more insight on Trump's potential plans for energy policy. In the briefing, Cramer suggests that Trump could eliminate a federal rule to protect waterways and wetlands, an EPA regulation setting methane emissions standards, and the Clean Power Plan. Describing the briefing in an interview, Cramer said that any energy policy would incorporate all forms of energy, without punishing coal, oil, and natural gas production. Further details are expected in a speech by Trump at an oil conference on Thursday. Both Republicans and environmental groups are concerned over Trump's unclear position.
NPR: In 1965 NIST in Gaithersburg, Maryland, built a machine that uses a stack of stainless steel plates to apply up to 1 million pounds (4.4 million N) of force to test materials' physical properties. It was then, and still is, the largest machine of its kind in the world. Over the past year-and-a-half, the machine underwent refurbishment for the first time. The weights, which accumulated damage over the years, were repaired, and the entire machine was taken apart and then put back together and recalibrated. Earlier this month the machine returned to operation and is working through a backlog of measurement requests.
New Scientist: Asteroids and comets more than 1 km across could devastate Earth if they were to hit the planet. However, Desireé Cotto-Figueroa of Arizona State University in Tempe and her colleagues say that we may not have as much to worry about from asteroids as we thought. Cotto-Figueroa's team tested centimeter-sized cubes from meteorites recovered on the ground. By crushing the samples, the researchers found that the asteroids were nearly as brittle as concrete, which means they are much weaker than most Earth rocks. The researchers extrapolated their measurements of the samples up to much larger scales to calculate the break-up rate for different sizes and types of meteorites. The calculations suggest that rocky asteroids are much more likely to break apart in Earth's atmosphere and turn into a spray of fireballs instead of remaining whole and creating large impacts.