Science

A dark plume leapt into the sky over southern Mexico. Below, waves of hot gas and rock screamed down volcanic slopes, stripping the mountain and surrounding area of vegetation, killing any living thing in their path. It mixed with rivers to create torrents of water, mud and other material as thick as wet concrete. For days afterward the air was choked with ash—microscopic shards of glass—that sickened survivors who inhaled it. It fell like snow onto the surrounding landscape, jamming rivers to create massive floods that wreaked havoc on agriculture. It was A.D. 540, and El Chichón—a small and previously unremarkable volcano—had plunged Maya civilization into darkness and chaos. At least that is the story according to a new paper published in the February Geology, jumping into the long-running archaeological debate about what drove Maya civilization—one of the most sophisticated of its time—into a century-long “dark age.” The Maya, who thrived from A.D. 250 to …

Slowing down: the Sun as seen by the SDO Sunlight is slowing the rotation of the Sun’s outermost layers by stealing its angular momentum. That is the claim of researchers in the US and Brazil who have studied acoustic waves oscillating through the Sun’s visible surface – the photosphere – to determine how fast the Sun spins at certain depths. It has been known since the 1980s that the outer 5% of the photosphere rotates more slowly than deeper layers. However, solar physicists do not understand why this slowdown occurs, its total extent and its effect on the Sun’s magnetic dynamo and solar wind. To solve this puzzle a team led by Ian Cunnyngham and Jeff Kuhn of the Institute for Astronomy at the University of Hawaii has observed acoustic waves at the limb (edge) of the Sun’s disc using the Helioseismic and Magnetic Imager on NASA’s Solar Dynamics Observatory (SDO), which orbits Earth. Bell …

Related images(click to enlarge) The majestic auroras have captivated humans for thousands of years, but their nature — the fact that the lights are electromagnetic and respond to solar activity — was only realized in the last 150 years. Thanks to coordinated multi-satellite observations and a worldwide network of magnetic sensors and cameras, close study of auroras has become possible over recent decades. Yet, auroras continue to mystify, dancing far above the ground to some, thus far, undetected rhythm. Using data from NASA’s Time History of Events and Macroscale Interactions during Substorms, or THEMIS, scientists have observed Earth’s vibrating magnetic field in relation to the northern lights dancing in the night sky over Canada. THEMIS is a five-spacecraft mission dedicated to understanding the processes behind auroras, which erupt across the sky in response to changes in Earth’s magnetic environment, called the magnetosphere. These new observations allowed scientists to directly link specific intense disturbances in the …

Atomic friction: tiny effect may never be measured
 An excited atom decaying in a vacuum experiences a force very similar to friction, according to calculations done by physicists in the UK. At first sight, the result appears to violate Einstein’s equivalence principle. However, the researchers calculate that, in fact, relativity rides to its own rescue, and the mass lost from the atom as it decays to the ground state allows it to lose momentum without slowing down. Einstein’s special theory of relativity famously says there is no such thing as absolute motion: the laws of physics are the same in all inertial frames of reference. Theoretical physicists Matthias Sonnleitner, Nils Trautmann and Stephen Barnett at the University of Glasgow noticed an apparent contradiction, however, when considering a textbook quantum-mechanics problem. An excited atom in a vacuum decays to a lower energy state, emitting a photon in a random direction. For simplicity, the problem is normally …

From Shakira to Travolta, some people just know how to shake it on the dance floor. What’s their secret? A study published in Scientific Reports this week has identified some of the common body movements that seem to characterize the best female dancers—in a social setting at least: hip swings, plus some coordinated asymmetry in the arms and legs. The study’s authors also offer up some theories about why these particular moves get dancing queens noticed. (Hint: it’s about sex.) Nick Neave, an associate professor of psychology at Northumbria University, and his colleagues launched this study as a follow-up to an earlier experiment. In 2011 they examined which male dance moves proved most attractive to the opposite sex. It turned out women favored men who varied their neck and torso movements when they danced. (Forget the monotonous head bob, boys.) The women also took note of the speed at which male dancers moved and flexed …

In football there are few plays more thrilling than a last-second field goal attempt: both teams line up with the clock one or two ticks from zero. The ball is snapped and the crowd roars as the kicker charges forward in an effort to drive the ball through the yellow uprights, the fate of his team hanging in the balance. Yet why do some kickers rise to the challenge whereas others choke under pressure? It may have more to do with their mental state than physical ability, one psychologist says. “Choking” is a term that has seeped into the vernacular to describe those big moments when athletes—or any individuals in a stressful situation—are unable to perform well under pressure. Choking, however, has little to do with failing to pull off the unbelievable (a 60-yard field goal in a blizzard, for example) nor does it describe a random off-day, performance-wise. Rather, Sian Beilock, a neuroscientist who …

Fully charged: the atomtronic battery in action A battery-like device that supplies a current of ultracold atoms has been created by physicists at the University of Colorado in Boulder. Their “atomtronic” battery is based on a Bose–Einstein condensate (BEC) and could be used to supply circuits made from transistors and other components that operate using atomic rather than electronic currents. Potential applications of the battery include inertial sensing and quantum-information processing. Atomtronics is a new field of applied physics that aims to create analogue and logical circuits using currents of atoms. According to Boulder’s Dana Anderson, “practical devices do not yet exist”, and his team is focused on developing an atom transistor and simple transistor circuits. In 2016 Anderson and colleagues reported the development of an atomtronic transistor based on a magneto-optical trap that contains three potential energy wells. Now, Anderson, Seth Caliga and Cameron Straatsma have created an atomtronic battery that, in principle, could …

A new leaf: the Oak Ridge logo was transmitted at 87% fidelity The efficiency of data transmission through ordinary optical fibres has been enhanced using a quantum-mechanical technique known as superdense coding. Physicists in the US have shown that they could nearly double the capacity of a fibre link compared with conventional transmission – and the researchers say their work could increase how much data the internet can handle. Superdense coding exploits the phenomenon of entanglement to double, at least in principle, the capacity of an information channel. A single binary bit sent down a channel can normally encode two possible values – 0 or 1. But a single quantum bit, or qubit, that is entangled with a second qubit some distance away can instead encode four possible values. This is because the two particles, even though spatially separated, are strongly correlated with one another and so effectively act as a single entity. The total …

Members of a House of Representatives committee hammered the Environmental Protection Agency on Tuesday at a hearing titled “Making EPA Great Again,” accusing it of basing its regulations on biased, politicized science, and calling for reforms in the EPA’s rule-making process. But a number of scientific organizations call this an attempt to covertly strip the agency’s power—and ultimately to interfere with the scientific process itself. In his opening statement at the House Committee on Science, Space and Technology hearing, Chair Lamar Smith—a Republican from Texas—excoriated the EPA over what he has called its “secret science.” In setting past environmental regulations the EPA has “routinely relied on questionable science, based on nonpublic information, that could not be reproduced…and deliberately used its regulatory power to undercut American industries and advance a misguided political agenda that has minimal environmental benefit,” Smith said. With Pres. Donald Trump’s administration newly in charge, Smith added that he now sees a chance …

Kristina Trotta was working for the Florida Department of Environmental Protection (DEP) in Miami in 2014 when she and her colleagues were called into a staff meeting. “We were told by the regional director that we were no longer supposed to say ‘global warming,’ ‘climate change’ or ‘sea level rise,’” says Trotta, who works on coral reef conservation. “We were finally told we are the governor’s agency and this is what the governor wants, and so this is what we’re going to do.” Florida’s hush order, along with a similar effort in North Carolina, offers a preview of what will happen if Pres. Donald Trump continues preliminary moves to muzzle climate communication from key federal agencies. The Florida gag effort was part of a broader move by Gov. Rick Scott, a Republican who questions the scientific consensus on climate change. Experts and local officials say it hampered community efforts to plan for worsening flooding and …

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