October 8, 1909] 



SCIENCE 



495 



[by radiation] increases as it moves [faster] 

 . . . but only as it receives this particular 

 form of energy," * Professor Speyers is, it 

 seems to me, endeavoring to express a distinc- 

 tion which must be recognized, but in terms 

 which can not be admitted if non-Newtonian 

 mechanics is accepted. The mass of the ether 

 is only temporary; it does not become infinite 

 though moving with the velocity of light, and 

 it can be transferred. There are not, however, 

 two kinds of energy — one the energy of me- 

 chanical motion, the other, radiant energy. 

 There is only one energy in the physical uni- 

 verse, but two sorts of mass — temporary for 

 ether, permanent for matter, both of them 

 being energy of ethereal rotation. I am en- 

 tirely in agreement with Professor Lewis that 

 the substance (meaning by this word no ordi- 

 nary matter everywhere and at all times amen- 

 able to gravitation, nor yet a purely meta- 

 physical substance, but a universal interstellar 

 medium which has physical properties differ- 

 ent from ordinary matter) " which in a beam 

 of light has mass, momentum and energy, and 

 is traveling with the velocity of light, would 

 have no energy, momentum or mass if it were 

 at rest " ; but " if it were moving with a 

 velocity even by the smallest fraction less than 

 that of light," it would cease to be free ether, 

 and would have quite different properties. 

 Now this is just what might be expected if 

 matter is formed from the ether, for however 

 it may be formed, matter must be differen- 

 tiated from the ether by a per saltum change, 

 ordinarily irreversible. Whether we consider 

 the condensation of a large volume of ether 

 containing a powerful luminous energy into 

 the dimensions of a corpuscle still retaining 

 the electro-magnetic energy of the original 

 volume, or regard the birth of an elementary 

 particle as in the nature of a cataclysm which 

 opens a rift in a medium of great strength 

 and density, in other words, whether we con- 

 ceive the ultimate particles of matter to be 

 vacuities in an exceedingly dense ether, kept 

 from collapsing by the centrifugal pressure of 

 a rapidly rotating shell, or as condensations 

 in an elsewhere excessively rarefied medium, 



in either case the circumscribing of a definite 

 volume with properties other than those of the 

 general medium presupposes a surface of dis- 

 continuity of some sort around the segregated 

 portion, such as might be produced by a sud- 

 den change in the ethereal velocity at this 

 singular surface. It may be a question 

 whether the permanent mass (m„) of a ma- 

 terial body is exactly equal to its ethereal 

 angular momentum divided by the velocity of 

 light 



nu = M'/V. 



The circumscribing of the ethereal motion 

 may be attended by some departure from the 

 universal velocity in the free ether, but this 

 is simply to say that the materialized ether 

 is distinct from the free ether. 



In an article in Nature'^ Professor Larmor, 

 in commenting on the fact that the Doppler 

 effect requires " some kind of thermodynamic 

 compensation, which might arise from ethereal 

 friction, or from work required to produce the 

 motion of the body against pressure excited 

 by the surrounding radiation," says : " The 

 hypothesis of friction is now out of court in 

 ultimate molecular physics," but it comes into 

 court again with the discovery that atoms are 

 destroyed and that new radiant energy is 

 thereby imparted to the ether. If radiation, 

 in turn, generates mass, as I have suggested 

 in my paper, " A Cosmic Cycle," ' or in the 

 less problematical way which Professor Lewis 

 has now virtually demonstrated, it is difficult 

 to conceive how this can be done without some 

 sort of ethereal reluctance analogous to vis- 

 cosity in a gas; and granting such a reluc- 

 tance, we might anticipate some retardation 

 of the normal ethereal velocity in the trans- 

 formation. 



In the paper cited, I have defined energy as 

 " the modification of ethereal rotation, or the 

 establishment of rotation at new points in the 

 ether." Radiant energy is electromagnetic 

 rotation of the ether, differing in no wise es- 

 sentially from the ethereal rotations within an 

 atom whose energy makes the atomic mass, 



"Vol. 63, p. 216, December 27, 1900. 

 'American Journal of l^cience, 13, 193, March, 

 1902. 



