What Happens at Absolute Zero?

[caption id="attachment_7397" align="alignright" width="440"] Bose-Einstein condensate at billionths of a degree. Image by NIST[/caption] Classical physics suggests that at absolute zero, particles cease all motion. But what about quantum mechanics, the science of the very small? Ah, therein lies the rest of the story. From Gas to Frigid Solid It is well established fact that heated gas atoms or molecules move with great vigor. In fact, gas expands as energy increases, due to increased particle momentum. The reverse is also true. Cool a gas and it shrinks. Particle motion decreases. Particle momentum decreases. The atoms or molecules come closer together. At some point a liquid forms. Cool the liquid further and the result is a solid. Keep cooling the solid, and in theory it is possible to reach the coldest…
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