Page:Popular Science Monthly Volume 82.djvu/307

in 1,000 years by radio-active transformation, or enough to last at the same rate for 1,000,000 years, the thermal energy corresponding to the mass-energy of one gram is $3\times (10)^{12},$ which is very nearly the same as the $5\times (10)^{12}$ water-units, computed by De Volson Wood for the specific heat of the ether.^[1] We seem, at any rate, to be approaching limiting values which are perhaps connected with the transition from ether to matter, or the reverse. If a volume of rotating ether, having a specific heat of $5\times (10)^{12},$ can be condensed, or in any other way transformed into a volume of matter with specific heat unity, since specific heat is capacity for absorbing thermal energy, the tremendous shrinkage of this capacity during the formation of matter out of ether represents the absorption of so much energy, and the almost complete saturation of the original capacity. It follows that if the process is reversed, the thermal energy of atomic formation must be set free.

Since radium decays far more rapidly than most elements, the one million years suggested in the preceding illustration must be greatly extended in order to represent the average duration of matter. Similarly, the one million light-years deduced for the distance of the fainter nebulæ on the Lick Observatory plates is not a limiting distance beyond which light can not penetrate, but it is a distance at which light is reduced to perhaps eight per cent, of its original intensity, or a quantity of that order. It is evident from the phenomena connected with the decay of the radio-active elements, that different elements have different durations. The rarer elements are either those which require a very long time and a long process of successive ethereal modifications in their development, or else they are elements which are relatively unstable, and which decay more rapidly than the others.

Rutherford gives the radius of an electron as $1.4\times (10)^{-13}$ cm., on the supposition that the electron is a sphere, in which case its surface will be $2.5\times (10)^{-25}$ sq. cm., and its volume $1.1\times (10)^{-38}$ cub. cm. The mass of an electron being, according to Sir J. J. Thomson, 1/1700 times that of a hydrogen atom, and the latter weighing $1.1X(10)^{-24}$ gram, the density of an electron works out

$D=\left({\frac {1.1\times 10^{-24}}{1.7\times 10^{3}}}\right)\div \left(1.1\times 10^{-38}\right)=5.9\times 10^{-10}\ (water=1)$

This value is so extraordinary that obviously we are not dealing with any ordinary problem in material density. The only phenomenon which has any resemblance to it is the increment of mass which the electron acquires at velocities approaching that of light in Kaufmann's experiment. Add to this the fact that the velocity of light is a constant, and the conclusion apparently follows that if the velocity of wave-motion in the ether can be diminished to even the smallest extent below that of light, the medium ceases to be ether, and the motion ceases to be ethereal wave-motion, but is left behind as the beginning

1. Philosophical Magazine for November, 1885, pp. 402–403.