Memorial to the Classical Statistics

NE of the most elusive and perplexing, hazy and confusing of the parts of theoretical physics is that which bears the name of "statistical mechanics".* On the principle that a tree is to be judged by its fruits, this must be ranked as high as the tree which bore the golden apples of the Hesperides; for among its fruits are the Maxwell-Boltzmann distributionlaw, the black-body radiation law, the value of the chemical constant, the Fermi distribution-law for the electrons in metals, the alternating intensities in band-spectra--and indeed the tree might lay a valid claim to the whole of quantum-theory. The singular thing is that such wonderful fruits should have grown from, or should have been grafted upon, so badly-rooted a tree. To change the metaphor, one frequently feels that the superstructure is sustaining the foundations, and the premises are flowing from the consequences, rather than the other way about. Perhaps anyone who feels this way should be disqualified from writing about the subject; but on the present occasion, the attempt is going to be made. Statistical mechanics--hereinafter to be called "S.M." at times for short-- did not of course arise from any desire to solve the problems suggested above, which came late. It seems to have sprung from attempts to answer older questions, of which the following may serve as an example. Consider a gas in a box, with an electric fan or something of the sort fitted inside to stir it up. The gas having been stirred up, the fan is stopped, leaving it in a state of surging and whirling about within the confines of the box.