The Bridgeport times and evening farmer., 1921-06-21
MILL ATTEMPT ID PROVE THEORY
 OF RELATIvITy

Chicago, June 21. (By the Associ- ated Press. )-The Einstein theory of relativity is to be subjected to a new practical test by Prof. Albert A. Mi chelson of the University of Chicago, whose discoveries led to its formula ton. The forthcoming experiment is expected to lend substantial sup port to the theory or to disprove 1r-
 Prof. Nicholson, who is now lectur- ing at the University of Paris, is eX- pected back about July 1st and the test is planned within the next year. It will be conducted under the aus piees of the University of Chicago, either in this city or in some noun tainOuS country
 The experiment has been undertak- en at the request of pr. Ludwick Sil- berStein of the Eastman Research Laboratories at Rochester, N Y., who has worked out it's terms It is said that Professor Albert Einstein on his recent visit to the United States ex- the experiment.
 Just what it is planned to do to determine whether Einstein's theory holds or not was explained here to- day by Prof. Robert A. Mi1likan, col league of Prof. Nicholson in the de partInent of technical details. Prof. MiIlikan said:
 This is, as a matter of fact, an ex- pertinent suggested by Prof. Michel son 20 years ago as one way of test ing whether of not it is possible to de- tect a motion of the earth with re- spect to the medium which carries a light
 '.An efforts thus far made to de- tect by means of light affects the mo tion of any material body with re- 5pect to the other have failed But all preceding attempts have been made with the idea of trying to mea- sure the linear motion through space of a point on the earth with respect to the ether surrounding that point fIon h f7y- A1,@1 fT7kaf1 have been wholly negative.
 ''In other words the observed eff Tects have been precisely those to be expected if there is no relative mo ion of the earth with respect to the ether at all. To illustrate, if an ob- server were himself immersed in a great sphere of rotating water and were to send sound signals simultan- eously forward in the direction in which he is moving and also back ward. and if these sound signals were reflected by mirrors placed at equal distances ahead and behind him, the echoes would obviously come back at exactly the same instant, provided there were no relative motion be- tween himself and the water. In other worlds he could not detect by such an experiment the movement of himself or the water unless he were moving more rapidly or more slowly than the water, in which case he would be able to detect and to mea- sure relaI1V6 1nO1On With respect to the water by the difference in the time of return of the echo from the forward mirror and the back mir TOT.
 Now the results of all experiments of this sort up to date in which we have sent light signals forward and back have been to show no differ ence in the time of the return of the light echo to the observer. From this the conclusion has been drawn | that the ether, if 1t exists at ali moves with the earth so as to make it impossible to detect any relative | motion,
 '"The special theory of relativity as | generally stated consists in the as- sertion that it is impossible to de- | tect the motion of any body with re- spect to the ether. The statement l would be more conservative if put in l the form that all experiments up to | the present have failed to detect such | relative motion.
 Now Prof. Nicholson pointed out 1 some 20 years ago that if the ether is 1 dragged along with the earth at its 1 surface, it would have to be dragged 1 Tn different amount near the equa- tor than near the pole, because ot 1 the fact that the motion of rotation Of the earth is greater at the equator | than at the poles. Hence one way 1 of testing whether or not we can de. | feet motion of points on the earth. surface with respect to the ethel
 
 | different directions around the earth's surface with respect to the | ether would be to send a light sigma in different directions around the | earth's pole and see whether the two l signals came back to the startins | point at the same instant. If there were any relative motion of the eartf | with respect to the ether they would | not do so. But if the ether in tho nefghborhood of all portions of tht earth lad the same motion as the ! earth t'IHt beneath it, then the two 1 s.snals would come back at exactly the same time, for the experimen! | would be quite analogous to that O. 1 an observer in the big tank of reIat | ing water mentioned above.
 "The experiment was not tried il l this form because it was thought tha 1 the form that Prof. Nicholson diC employ was practically equivalent t, it and showed that the result would have been negative if it had beer | tried.
 | Now pr. Silberstein has asked | Prof Nicholson to take up again tn l projected experiment because he ha
 computed that if the general theor. | of relativity is correct. there shou1t
 be a difference in the time of return
 to the source of signals sent in op | ,nfa fr