Gravity Wave Detection Well Before Einstein’s Prediction
Similar Famous Interferometer Experiment in 1887 Led to Theory of Relativity
WASHINGTON, D.C. (February 13, 2016) – Although the detection of gravity waves has just been announced, the same basic principle and device – the Interferometer – was used by two scientists more than 100 years ago in a famous experiment which led to Einstein’s theories of special and general relativity, and to the prediction of gravity waves from the collision of black holes.
Had those Gravity Wave Detection experimenters been looking for gravity waves instead of evidence of an aether filling space which permitted light waves to propagate, they might have discovered gravity waves in 1887 – although it would have required much more sensitive equipment – says Professor John Banzhaf of GWU.
Scientists Albert A. Michelson and Edward W. Morley [MM] were seeking to prove that the earth and all heavenly bodies moved through an undetectable aether which was what permitted light – which was then believed to be solely a wave – to propagate.
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To do this they used an Interferometer which split a beam on light into two components which shot off in two directions in arms perpendicular to each other. Then, by examining the interference fringe patterns which are produced when the beams were reflected back, they could tell if there were any delays – i.e., if anything caused one beam to arrive before or after the other.
They believed that the speed of light would be different in the arm which was pointed in the direction of the motion of the earth through the aether than in the other arm perpendicular to movement. Although their inability to detect any such difference was initially regarded as a failure, it actually showed that the speed of light is constant and does not very with the velocity of the observer.
That finding led Einstein to postulate his special theory of relativity. That in turn led to the general theory of relativity, the prediction of black holes and gravity waves, and calculations of the appearance of gravity waves resulting from the interaction and eventual collision of two black holes.
The fundamental difference between the two experiments is that MM expected that the interference fringes, showing a difference in the time at which each light pulse arrived back where it began, would change when the Interferometer was rotated, but it did not.
The LIGO experimenters expected that the fringes would not move, but rather would fade in and out. When they did, and in exactly the same way gravity waves would be expected to be generated by colliding black holes, the existence of gravity waves was demonstrated for the first time.
JOHN F. BANZHAF III, B.S.E.E., J.D., Sc.D.
Professor of Public Interest Law