Physicists from Germany have recorded the coldest temperature ever recorded.
Absolute zero is -273.15 °C, the lowest temperature that exists on the thermodynamic scale.This is the point at which there is no nuclear motion or heat at all.It was believed that scientists would never be able to reach this mark, as it was impossible to remove all the kinetic energy from the atoms in the system.
But the authors of the new work in the study recorded a temperature of 38 picokelvin or 38 trillion degrees above absolute zero.
To achieve this, the authors started with a cloud from100 thousand rubidium atoms, which were captured by a magnetic field in a vacuum chamber. They then cooled it to form a quantum gas called Bose-Einstein Condensate (BEC). In it, the atoms start to act like one big atom.
But the temperature was not low enough, soThe team conducted an experiment in which they dropped a Bose-Einstein condensate trap 120 m. During the free fall, the team turned on and off the magnetic field containing the gas several times.
When the magnetic field is off, the gas startsexpand, and when it is turned on again, the gas is forced to contract again. This switching slows the expansion of the gas almost to a complete stop, and a decrease in molecular velocity lowers the temperature.
As a result, the authors managed to reach record temperatures in just two seconds. Simulations have shown that it can be maintained for up to 17 seconds in zero gravity, for example, on board a satellite.
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