Abstract
THERE is no upper limit to the temperatures which could conceivably be reached; in marked contrast to this, there is on the low temperature side a sharp boundary at -273-1° C.—the absolute zero of temperature. The boiling point of the most volatile gas, helium, lies about 4° C. above this limit; by reducing the pressure over liquid helium, it is easy to reach a temperature of 1° K., whilst 0-7° K. has been attained by the use of extremely powerful pumps. The contrast between the ease with which a high temperature can be generated-an electric torch is an example-and the complicated apparatus necessary to obtain a low one, is striking. It is due essentially to the fact that when a substance is heated there is not only an increase in its energy, but also in the internal disorder among its particles. In illustration, there is complete disorder in a gas, whereas a substance cooled sufficiently to cause it to crystallise has its constituents arranged with a high degree of order. In all affairs, it is easier to decrease order than to increase it; it is highly improbable that shaking a tray containing a number of black and white balls would increase the regularity of their arrangement.
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The Approach to the Absolute Zero. Nature 135, 777–778 (1935). https://doi.org/10.1038/135777a0
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DOI: https://doi.org/10.1038/135777a0