| Themes > Science > Physics > Cryogenics > Temperature > Is a negative Kelvin temperature possible? > Systems at negative absolute temperature |
Nevertheless, both systems at infinite temperature and at negative absolute temperature can be prepared. Let us look first at negative temperature. In most lasers atoms are excited electronically to a high energy level. Prior to laser light emission of the whole system, more atoms have to be excited than are not, and a negative absolute temperature can be ascribed to the system. Note that, as expected, atoms are not excited by heating. |
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