A couple of weeks I ago I wound up with frostbitten fingers after an ill-advised cold-snap bike ride. It was minor in the grand scheme of frostbite, but I wound up with almost-alarming blue tinge and that characteristic thaw-pain that feels like all of your cells are about to burst open. Taking the actual wind chill together with the apparent wind chill of the moving bike, I'd say we were down to about 10 degrees Fahrenheit.That's nothing, of course. The average temperature of the universe is around −454.76 degrees Fahrenheit, while the current world record for laboratory-based coldness is about 0.0000000001 of a kelvin (0 kelvins being absolute zero). That record doesn't mean very much in terms of my fingertips, however—it was achieved by cooling the nuclear spins of a piece of rhodium metal. So: subatomic cold.Macroscale cold, or cold that we can see with our own eyes, is a different matter. At near-zero scales, it's much more difficult to achieve. Rather than dealing with the nucleus of a single atom, we're cooling many whole atoms together, which means restricting the innate motions—read: quantum fluctuations—of many atoms together. To this end, physicists have found a new way of cooling macroscale objects to below previously established limits via a technique known as "squeezed light," according to research published recently in Nature. It is cold that should not be.The macroscopic object in question was an aluminum plate about 20 micrometers in diameter, or a bit less than half the width of a human hair. This isn't exactly fingertip-scale, but it's an entirely different realm compared to subatomic particles.Read the rest at Motherboard.
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