Showing posts from March, 2024

Scientists Confirm the Incredible Existence of ‘Second Sound’

Usually, when something gets warmed up, heat tends to spread outward before eventually dissipating. But things are a little different in the world of superfluid quantum gas. For the first time, MIT scientists have successfully imaged how heat actually travels in a wave, known as a “second sound,” through this exotic fluid. Understanding this dynamic could help answer questions about high-temperature superconductors and neutron stars. In the world of average, everyday materials, heat tends to spread out from a localized source. Drop a burning coal into a pot of water, and that liquid will slowly rise in temperature before its heat eventually dissipates. But the world is full of rare, exotic materials that don’t exactly play by these thermal rules. Instead of spreading out as one would expect, these superfluid quantum gasses “slosh” heat side to side—it essentially propagates as a wave . Scientists call this behavior a material’s “second sound” (the first being ordinary sound via a dens

17th Edition Melting polar ice is slowing the Earth's rotation, with possible consequences for timekeeping

Global warming has slightly slowed the Earth’s rotation — and it could affect how we measure time. A study published Wednesday found that the melting of polar ice — an accelerating trend driven primarily by human-caused climate change — has caused the Earth to spin less quickly than it would otherwise. The author of the study, Duncan Agnew, a geophysicist at the Scripps Institution of Oceanography at the University of California San Diego, said that as ice at the poles melts, it changes where the Earth’s mass is concentrated. The change, in turn, affects the planet’s angular velocity. Agnew compared the dynamic to a figure skater twirling on ice: “If you have a skater who starts spinning, if she lowers her arms or stretches out her legs, she will slow down,” he said. But if a skater’s arms are drawn inward, the skater will twirl faster. Less solid ice at the poles, then, means more mass around the equator — Earth’s waist. “What you’re doing with the ice melt is you’re taking water tha