Never has it been so cold as at the University of Bremen. A team of scientists have tried to get closer to the coldest temperature in the universe, which is -273.15 ° C. Also called absolute zero, this temperature is theoretically impossible to reach, but it is nevertheless possible to approach it. This is what scientists at the Center for Applied Microgravity Space Technology (ZARM) in Bremen are doing.
Two seconds of intense freshness
The experiment lasted only two seconds: this is the time interval during which matter remained at 38,000 billionths of a degree above absolute zero. Or in other words 38 picoKelvin. Undetectable by a thermometer, this temperature could be identified with an “interferometer”, an instrument that detects waves.
To get so low in mercury, the ZARM team had to create a cloud of rubidium gas and trap it in a magnetic field, inside a vacuum chamber. This gas has been cooled until it becomes a “Bose-Einstein condensate”, a phenomenon where the atoms form a single wave. The condensate was then thrown from the top of the 120 meter Bremen drop tower under the influence of magnetic fields. It was during these two seconds of fall that the temperature of matter approached so close to absolute zero.
Deepen knowledge in quantum physics
Temperature experiments allow scientists to study phenomena in quantum physics. At absolute zero level, Bose-Einstein condensate makes quantum effects visible on a microscopic scale. Since temperature is directly related to the movement of atoms (entropy), cooling materials to levels close to absolute zero allows atoms to be completely immobile. Helium, for example, becomes superfluid at -271 degrees, that is to say that it no longer has any viscosity and can pass through matter!
In the past, several experiments had already been carried out to approach absolute zero. The ZARM team nevertheless thinks that it would be possible to maintain the temperature beyond two short seconds, and aims to reach seventeen seconds thanks to the weightlessness … of space!
Source: UsineNouvelle – Actualités A la une by www.usinenouvelle.com.
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