Year in Review: Below absolute zero, but hot

Lab trickery achieves negative temperature

By Andrew Grant, 17:12 PM December 12, 2013


Ulrich Schneider must be a hit at cocktail parties. The physicist at Ludwig Maximilians University of Munich can tell awed guests that he is responsible for creating both the world’s hottest substance and lowest temperature — at the same time.

Schneider’s substance — a gas consisting of about 100,000 potassium atoms — reached a temperature below absolute zero, about –0.000000001 kelvins.

Unlike Fahrenheit and Celsius temperatures, where the zero point is arbitrary, absolute temperature (measu...

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