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Scientists Race to Bottom of Thermometer

My home city of Ottawa is currently the coldest capital on Earth, but scientists can now pinpoint the coldest spot in the universe.

NASA's Cold Atom Laboratory (CAL) aboard the International Space Station recently set a global record--who knows, maybe even a cosmic one--for cooling matter down to an insanely chilly 0.0000001 of one degree Kelvin (K) above absolute zero, about -273.15 Celsius.

CAL arrives at the International Space Station in May, 2018


For comparison, the average temperature of interstellar space doesn’t get colder than a relatively balmy 2.7 K. (The Kelvin scale is a scientific version of the Celsius and Fahrenheit scales, the major difference is that it starts at “absolute zero”, a theoretical temperature at which all motion, and therefore temperature, stops).

CAL represents part of a new global frontier in cold science research in which physicists are in a race to the bottom of the thermometer.

Scientists believe that ultra-cold atoms hold the answers to some of the biggest cosmic mysteries, from dark matter to why there’s more matter than antimatter. And if you want to study atoms in detail, you need to keep them very, very still—and this means cold.

CAL’s goal is to use atom-chilling temperatures to study the fifth state of matter, a Bose-Einstein Condensate (BEC). In a BEC, the slow-motion causes millions of atoms merge their identities to form a remarkable single quantum entity. And zero gravity gives physicists the ability to study BECs for up to ten seconds—the equivalent of a feature-film length of time compared with the previous snap-shot experiments on Earth.

In the Ultra-Cold Neutron experiment at TRIUMF in Canada, physicists are getting a never before seen view of neutrons by cooling them to 0.003K. Using a clever quantum mechanically-mediated technique, this slows neutrons from about 500-meters-per-second at room temperature, to less than 8-meters per second (about the speed of an Olympic 100-meter sprinter). The UCN physicists are hoping that at this speed they’ll get a clear measurement of whether the overall neutral neutron actually internal electrical poles something that amazingly hints at how the cosmos started.

Finally, under a mountain in Italy, an international group of physicists have created a physics detector that’s the coldest square meter of stuff in the universe, cooled to just 0.01K. The CUORE experiment is one of several competing searches for the postulated, and wonderfully esoteric-sounding neutrino-less double beta decay. It’s observation or non-detection is thought to hold clues about big issues from the cosmic matter-antimatter asymmetry to the nature of dark matter.

As for me, -20 °C is enough to slow me down to just about still—especially on a Saturday with a wood stove and good book.



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