Physics Today’s online staff summarize the most important and interesting news about science from the world's top media outlets.
There are 56 posts for the selected month (September 2016).
BBC: Shape-shifting materials typically require an external trigger to initiate the shape change. Now Sergei Sheiko of the University of North Carolina at Chapel Hill and his colleagues have developed a polymer in which the transformation occurs at a predetermined time with no outside stimuli necessary. The researchers created a polymer with two types of chemical bonds: permanent and dynamic. The permanent bonds define the material's final shape; the dynamic bonds control how quickly the material can reach that shape, depending on the strength and concentration of the bonds. The timing precision is limited to a scale of minutes to hours, but that may be sufficient for the material to be used for applications such as drug delivery.
National Geographic: A study in Nature that presents the most complete reconstruction so far of 2 million years of global sea-surface temperatures has been both praised and panned by scientists not involved in the work. The scientists say the reconstructed data will play an important role in establishing a clear understanding of Earth's climate history. But it's the conclusion that the paper's author draws—that even if all further greenhouse gas emissions were capped, global temperatures could still rise by up to 7 °C—that has received harsh criticism. The author, Carolyn Snyder, who is now at the US Environmental Protection Agency, says that the prediction was not the primary goal of the work; she was just examining what the relationship between sea-surface temperature and atmospheric carbon dioxide levels might mean in the future. But other scientists argue that she has incorrectly extrapolated the future relationship by basing it on past climate changes that were caused by factors other than greenhouse gases.
New bill would require universities receiving federal funding to report professors’ sexual harassment
Science News: In 2009, a star 19 million light-years away increased in brightness over the span of several months, eventually reaching a luminosity 1 million times that of the Sun. The star appeared to be going supernova. But instead of progressing to a tremendous explosion, the star suddenly disappeared. Thinking that the star had perhaps been hidden by a cloud of dust, Scott Adams of Caltech and his colleagues used the Hubble Space Telescope to examine the region of sky. Where the star had been, they found a faint IR signature, which they believe is evidence of material falling into a black hole that formed via the star's collapse. If the interpretation is correct, then this is the first star known to have become a black hole without first going supernova. Such a process has been described in theories that say some stars are so massive that the supernova process cannot overcome the stars' own gravity. If the star did become a black hole, the debris falling in is likely emitting x rays. Adams's team is awaiting observations from the Chandra X-Ray Observatory.
Reuters: On 18 September Canadian environment minister Catherine McKenna announced that the government would put a price on carbon emissions from any of the country's provinces that do not adequately regulate emissions themselves. The policy will go into effect in October, McKenna said. She did not provide details about how the price would be set, what efforts the provinces are expected to make, or how the government would enforce the payments or penalties. She also did not address whether the current government would be altering the previous government's pledge to cut emissions to 30% below 2005 levels by 2030, a target that is likely unreachable without significant efforts by both the national and provincial governments.
Guardian: A common claim from those disputing the hazards of anthropogenic climate change is that rising carbon dioxide levels have led to increased global plant growth. There is some evidence supporting that claim. However, a new paper suggests that now that the global CO2 concentration has surpassed 400 ppm, the detrimental effects of rising temperatures will outweigh the benefits of further CO2 increases. Between 1998 and 2014, researchers at Stanford University grew 132 plots of common California flowers and grasses and varied the temperature, water, and CO2 and nitrogen levels. The results showed that plant growth increased with higher concentrations of nitrogen and decreased with rising temperatures. But beyond current global atmospheric levels, CO2 had no notable effect on plant growth.