# Page:Popular Science Monthly Volume 79.djvu/259

One familiar with modern electrical theories knows that the present tendency is to include everything in the electromagnetic scheme. Maxwell started this when he promulgated the electromagnetic theory of light. Experiment by Kauffman on the beta rays of radium lead us to regard mass as electromagnetic. Hence it is very natural to try to explain gravitation as an ether-phenomenon. This would require that the ether be capable of supporting enormous pressure or tension. In the older views the ether was regarded as a very attenuated medium. Such an ether can hardly meet the demands. Many modern physicists regard the ether as very rigid and dense when compared with ordinary matter. See Lodge's "The Ether of Space." If we follow Sir J. J. Thomson, who regards all mass as mass of the ether we can calculate the density of the ether, for the mass of an electron is about $10^{27}$ grams and the volume is of the order of $10^{-39}$ cubic centimeters; hence the density of the ether is $10^{12}$ or a million million times that of water. When we consider the rapidity with which an ether disturbance is transmitted we see that the rigidity should be very great compared with ordinary matter. Taking the density of ether as $10^{12}$ and the velocity of ether waves as $3\times 10^{10}$ cms. per sec. the rigidity will be of the order of $10^{33}$ dynes per sq. cm., since $velocity={\sqrt {\frac {elasticity}{density}}}$ The intrinsic energy if due to rotational motion will be of the order of $10^{32}$ ergs per cubic centimeter, if we assume the velocity of rotation is of the order of that of light; since the energy $={\frac {1}{2}}$ mass times $velocity^{2}$ , where the mass of a cubic centimeter is $10^{12}$ grams and the velocity is $3\times 10^{10}$ cms. per sec. Hence the intrinsic energy and rigidity of the ether will probably meet the demands if we accept the views of ether and matter held by some of the greatest modern physicists. 