A team of physicists have set a new negative temperature record in a laboratory in Germany as they examine Bose-Einstein capacitors (BEC), the fifth state of matter. Not only did they approach absolute zero, they did so by simulating the vacuum conditions in space.
It is considered impossible to reach absolute zero, which corresponds to -273.15 ° C, the coldest possible temperature. This is because if temperature is a molecular vibration, there is a limit to cold, which is when the molecules stop completely. Scientists created the Kelvin scale to make it easier, with 0 degrees representing the absence of molecular motion (hence the term “absolute zero”).
Scientists explain that it is impossible to get to absolute zero in a lab, or anywhere else we might try, because we can never remove all the kinetic energy from atoms in a system. But the latest experiment really came close, reaching an effective temperature of just 38 pico Kelvin, or 38 trillion degrees above absolute zero.
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To do this, the researchers started with a cloud of 100,000 rubidium atoms trapped in a magnetic field in a vacuum chamber. Then they cool it to form a Bose-Einstein condensate, in which the atoms begin to function essentially like one large atom. Under these conditions, strange things can happen, a phenomenon that scientists often call quantum effects.
On that first foray, they managed to stay two billion degrees above absolute zero, but that wasn’t enough. That’s when I started simulating the vacuum environment in space. Scientists took the experiment to the European Space Agency’s Bremen launch tower, the Microgravity Research Center at the University of Bremen in Germany.
From a height of 120 meters, the team dropped the device with a Bose-Einstein condenser, and during the free fall, the magnetic field containing the gas was quickly turned on and off. This allowed the condensate to float in the absence of gravity, reducing the molecular motion of the rubidium atoms. Result: a temperature of 38 picokelvin (38 millionths of a first kelvin) for about 2 seconds.
And this was the absolute record for negative temperature, according to the team that published an article in the magazine physical review messages. The previous record was 36 millionths of a Kelvin, set by scientists at the National Institute of Standards and Technology in Colorado.
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