New Britain herald., 1921-06-21
IS TO BE TESTED
University of Chicago Professor
 Preparing Experiments

Press) Tho Einstein theory Of rela-
 tivity is to be subjected to new
 practical test by Prof , Albert A.
 Nicholson of the University of Chica- [ go. whose discoveries led to its formu- lation. The forthcoming experiment
 is expected either to lend substa ntial support to the theory or to disproye it.
 Prof. Nicholson who is now lectur-
 ing at the University of Paris, is ex-
 pected back about July Ist and the
 test is planned within the next year.
 It will be conducted under the aus 1 pices of the University of Chicago, | either in this city or in some moun-
 tainous country.
 The experiment has been undep
 taken at the request of Dr. Ludwick | Silberstein of the Eastman Research
 laboratories at Rochester, N. Y, who | has worked out its terms. It is said
 that Professor Albert Einstein on his
 recent visit to the United States ex-
 pressed his belief in the efficacy of the experiment.
 Just what it is planned to do to de- | termine whether Einstein's theory | holds or not was explained here to- day by Prof. Robert A. Millikan, col league of Prof. Nicholson in the de- partment of physics of the University of Chicago. Divesting the subject of technical details. Prof. Millikan said:
 This is, as a matter Of fact, an experiment suggested by Prof. Michel son 20 years ago as one way of test ing whether or not it is possible to detect a motion of tho earth with re- spect to the medium which carries light.
 All efforts thus far made to de- tect by means of light effects the mo- tion of any material body with respect to the ether have failed. But all pre- ceding attempts have been made with the idea of trying to measure the linear motion through space of a point on the earth with respect to the ether surrounding that point, and the results thus far obtained have been wholly negative.
 "In other words the observed ef- fleets have been precisely those to be expected if there is no relative motion of the earth with respect to the ether at all. To. illustrate. if an observer were himself immersed in a great sphere of rotating water and were to send sound signals simultaneously forward in the direction in which he is moving and also backward, 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 between himself and the water. In other words, he could not detect by such an experi- ment the movement of himself or the water unless he were moving more rapidly or more slowly than the wa ter. in which case he would be able to detect and to measure his relative motion with respect to the water by the difference in the time of return Of tho echo from the forward mirror and the back mirror.
 Now the results of all experiments of this sort up to date in which we have sent light signals forward and back have been 10 show no difference in the time of return of the light echo clusion has been drawn that the ether, if it exists at all, 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 asser- ton that it is impossible to detect the motion of any body with respect to the ether. The statement would be more conservative if put in the form that all experiments up to the pres ent have failed to detect such relative motion.
 Now Prof Nicholson pointed out some 20 years ago that if the ether is dragged along with the earth at its surface. it would have to be dragged in different amount near the equa- tor than near the pole, because of the fact that the motion of rotation of the earth is greater at the equator that at the polise. Hence one way of testing whether or not we can detect motion of points on the earth's sur face with respect to the ether would | be to send a light signal in different l directions around the earth's pole and | see whether the two signals come | back to the starting point at the same | instant. If there were any relative | motion of the earth with respect to | the ether they would not do so. But | if the ether in the neighborhood of | all portions of the earth had the same motion as the earth just beneath it, | then the two signals would come back l at exactly the same time, for the ex- pertinent would be quite analogous to that of au observer in the big tank | of rotating water mentioned above. |
 The experiment was not tried in this form because 1t was thought that the form that Prof. Nicholson did ern- ploy was practically equivalent to it and showed that the result would have been negative if it had been tried
 Nov Dr. Silberstein has asked Prof. Nicholson to take up again the projected experiment because he has