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The record for the coldest temperature ever was broken with the cooling of rubidium gas to 38 picokelvins (3.8 * 10-11 K). The work could lead to new knowledge about quantum mechanics.
Temperature is a measure of the energy in the vibrations of atoms or molecules. The lowest theoretically possible temperature is absolute zero – 0 K or -273.15 ºC (-459.67 ºF) – which would require a complete stop of the movement. It’s probably impossible in practice, but for decades physicists have shown that we can get very, very close by using lasers to damp atomic motion.
In Physical Review Letters, scientists from Germany reported that they are getting closer to zero like never before.
Professor Ernst Rasel of Leibniz Universität Hannover and his co-authors placed 100,000 rubidium atoms inside a magnetic trap atop the 110-meter (360-foot) high Bremen Drop Tower of the University of Bremen. The trap forms what is called a “matter wave lens” which, by focusing atoms to infinity, cools them to the point where they become a Bose-Einstein condensate (BEC), a state of matter. where collections of atoms can show quantum behavior as if it were a single particle / subatomic wave.
Closing the trap allows the condensate to expand in all directions, cooling it further. The BEC was then cleared to free fall down the length of the tower while the detectors observed its behavior.
The whole process only takes two seconds, although modeling suggests 17 seconds is possible, and the authors hope to exploit this longer timeline to explore the behavior of the BEC with the vibration distortions removed.
In an accompanying point of view article, Dr Vincenzo Tamma of the University of Portsmouth, who was not involved in the research, said the work could “test gravity at the quantum level”. The interference patterns in the BEC are determined in part by gravitational effects. With inconsistencies between our understanding of quantum physics and general relativity’s description of gravity representing perhaps the biggest unresolved puzzle in physics, the job offers an opportunity to explore physics at its lowest level. more fundamental. Tamma also sees potential for the technique to search for certain forms of dark matter.
One hundred thousand atoms might seem like a lot, but it’s actually about 50 million times smaller than the head of a pin, roughly for the variation in atomic size and pinhead. The coldest temperature reached in anything you can see was set when a 400-kilogram (882-pound) block of copper was cooled to 0.006 K. To get there, the researchers needed lead that had been mined. thousands of years ago, allowing time for radioactive isotopes to form. by exposure to other radioactive elements in the ore to decay. This was provided by the fortuitous discovery (for us) of a Roman galley that sank from the coast of Sardinia carrying Spanish lead intended for use in the Roman civil wars.
[H/T: Popular Mechanics]
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