Molecules are seriously chilling out. Scientists report the first cooling of molecules below a previously impassable milestone. The result, in which scientists cooled molecules down to tens of millionths of a degree, is a step toward reaching the ultracold temperatures already achievable with atoms, researchers report August 28 in Nature Physics.
Scientists regularly chill atoms to less than a millionth of a degree above absolute zero (‒273.15° Celsius), even reaching temperatures as low as 50 trillionths of a degree (SN: 5/16/15, p. 4). But molecules are more difficult to cool down, as they can spin and vibrate in a variety of ways, and that motion is a form of heat.