WEIGHING OF HEAT.

New Zealand Herald, Volume LXVII, Issue 20722, 15 November 1930, Page 5 (Supplement)

WEIGHING OF HEAT.

POSSIBILITY OF FUTURE. That lieat has weight, so that a billion atoms of hot load, for example, weigh an infinitestimal trifle more than the same metal when it is cold, is a recent deduction from the Einstein theories of relativity, communicated to the American Physical Society by Professor Richard C. Tolman, of the California Institute of Technology.

That light has weight is an earlier and more familiar deduction from these same theories, upon which deduction was based the estimated bending of light rays from distant stars as these rays pass close to tlio sun, one of the so-called proofs of the Einstein theories tested at recent total eclipses of the sun. Much the same reasoning applies to the probable weight of heat, and Professor Tolman has worked out complicated mathematical equations which indicate about how much weight the mere fact of being hot will add to samples of simple kinds of matter. The additional heat-weight is very tiny in amount, probably too small to be detected bv any present method of weighing or other physical experiment. Professor Tolman says he believes, however, that his deduction of a relation between heat and (he gravitation properties of matter is not only important as an item of pure physical theory, but may have significant theoretical or practical applications to some of the things that go on in the universe, like the generation and distribution of energy in stars, the properties of gaseous nebulae in space, and others. It is not even impossible, he suggests, that tho weighing of heat may be accomplished some day by laboratory experiment.