MICHELSON AND MORLEY EXPERIMENT (REPRODUCTION AND INTERPRETATION)
It compared the speed of light in perpendicular directions, in an attempt to detect the relative motion of matter through the stationary luminiferous aether ("aether wind"). The result was negative, in that the expected difference between the speed of light in the direction of movement through the presumed aether, and the speed at right angles, was found not to exist; this result is generally considered to be the first strong evidence against the then-prevalent aether theory, and initiated a line of research that eventually led to special relativity, which rules out a stationary aether.
The interpretation of results is that there is no displacement of the interference bands. The result of the hypothesis of a stationary ether is thus shown to be incorrect, and the necessary conclusion follows that the hypothesis is erroneous.
This conclusion directly contradicts the explanation of the phenomenon of aberration which has been hitherto generally accepted, and which presupposes that the earth moves through the ether, the latter remaining at rest.
The complete study of the ether-drift experiments of 1925, at Mount Wilson, leads to the conclusion that there is a systematic displacement of the interference fringes of the interferometer corresponding to a constant relative motion of the earth and the ether at this observatory of ten kilometers per second; and that the variations in the direction and magnitude of the indicated motion are exactly such as would be produced by a constant motion of the solar system in space, with a velocity of two hundred kilometers, or more, per second, towards an apex in the constellation Draco, near the pole of the elliptic, which has a right ascension of 262° and a declination of +65°.
In order to account for these effects as the result of an ether drift, it seems necessary to assume that, in effect, the earth drags the ether so that the apparent relative motion at the point of observation is reduced from two hundred, or more, to ten kilometers per second, and further that this drag also displaces the apparent azimuth of the motion about 45° to the west of north.
D.C. Miller. Ether Drift Experiments. // Nature, June 26, 1926, Vol.117, No 2956, P.890-891 (pdf)
It seems necessary to direct attention again to the fact that this experiment has never given a true zero or "null" effect in general; it has only given a "negative" result, that is, it has answered "no" to a specific question.
A.A. Michelson, F.G. Pease and F. Pearson. Repetition of the Michelson-Morley experiment. // Nature, Vol.123, No 3090, P.88, 19 January, 1929 (pdf)
The results gave no displacement as great as one-fifteenth of that to be expected on the supposition of an effect due to a motion of the solar system of 300 km/s.
(300/15 = 20 km/s — this value of the velocity of the ether wind is different from values of 6 km/s in the American edition of the same article published in March 1929 in JOSA).
D.C. Miller. The Ether-Drift Experiment and the Determination of the Absolute Motion of the Earth. // Reviews of modern physics, July 1933, Vol.5, P.203-242 (pdf)
The solar system might be thought of as a dynamic disk which is being pulled through a resisting medium, and which therefore sets itself perpendicular to the line of motion.
The predominating effect of the cosmic component while remaining constant in sidereal time, causes the minimum which occurs near sunrise in February to move progressively in civil time through the day, as the seasons change, so that in September it occurs near sunset; the time when the azimuth curve crosses its axis likewise shifts progressively in civil time.
The cosmic component of the earth's motion, which is the absolute motion of the solar system, is directed to the apex near the south pole of the ecliptic. The resultant motion in the course of a year traces on the celestial sphere the aberration orbit of the earth.
In order to account for the results here presented, it seems necessary to accept the reality of a modified Lorentz-FitzGerald contraction, or to postulate a viscous or dragged ether.
The actual observations indicate an ether drift of ten kilometers per second which varies in a manner wholly consistent with the theoretical requirements; however, the observed velocity of the drift is smaller than had been expected, as though the ether through which the interferometer is being carried by the earth's motion was not absolutely at rest.
In order to account for the results here presented, it seems necessary to accept the Lorentz-Fitzgerald theory of the contraction of matter moving through the ether, or to postulate a viscous or dragged ether as proposed by Stokes.
For nearly thirty years the results of the Michelson-Morley experiment obtained by Dayton C. Miller on Mount Wilson have stood at variance with all other trials of this experiment. As interest in Miller's results has continued to the present time, and since the original data sheets are available to the present writers, it has seemed appropriate that the observations be subjected to a new analysis. It is now shown that the small periodic fringe displacements found by Miller are due in part to statistical fluctuations in the readings of the fringe positions in a very difficult experiment. The remaining systematic effects are ascribed to local temperature conditions. These were much more troublesome at Mount Wilson than those encountered by experimenters elsewhere, including Miller himself in his work done at Case in Cleveland. As interpreted in the present study, Miller's extensive Mount Wilson data contain no effect of the kind predicted by the aether theory and, within the limitations imposed by local disturbances, are entirely consistent with a null result at all epochs during a year.
An Explanation of Dayton Miller’s Anomalous “Ether Drift” Result. (Thomas J. Roberts) (2006) (pdf)
This paper has not only explained how Miller was fooled, it has also presented a re-analysis of his data. This new analysis obtains a value of zero, and puts an upper bound on the “absolute motion of the earth” of 6 km/s (90% confidence level). This is fully consistent with similar measurements, and with the null result predicted by Special Relativity.
We are all prisoners of our time. While this paper gives solid and credible reasons to reject Miller’s result, it is unfair to attempt to judge him by the standards of today.
Does a Cosmic Ether Exist? Evidence from Dayton Miller and Others. (James DeMeo) (2014) (pdf)
Experiment of Michelson and Ether return to science. (Yu.N.Ivanov) (2012) (pdf)
Presentation is dedicated to find the actual causes, in consequence of which the Michelson interferometer has failed on the first purpose intended. Presentation is for theoreticians who are familiar with the Michelson experiment, do not agree with the interpretations available and willing to solve the problem.
A webapp that allows one to simulate the Michelson and Morley experiment and set a variety of conditions to determine what amount of fringe shift would be detected when the device is rotated from 0 to 90 degrees.
Variables include Lorentz contraction, refractive index, relative speed of frame (ether wind), path length, and wavelength.
A mathematical model of the Michelson-Morley experiments. Determination of the absolute speed of Earth’s motion. (K.S. Fasey) (2014) (pdf, in Russian)
This article does not purport to discard the equations of Lorentz and the relativistic justification of the results of the Michelson-Morley experiments. Nevertheless, it might be interesting to a wide range of readers, as an illustration of the fact how much the evaluation of the experiments’ results depends on the selected mathematical model. This choice can in fine even fully change the conclusions, which are made based on the results.
The truth about the results of Michelson-Morley’s experiments (А.А. Grishaev) (2010) (pdf, in Russian)
(excerpt of the book "This «digital» physical world", see pages 15-20)
How the aether has been found… and lost (P.A. Popov) (in Russian)
On the basis of the protocols of Michelson experiences, as well as those of his followers, there has clearly been an aether wind found, with a 10 km / s speed, in the plane of the interferometer. The lack of wind, declared earlier by the experimenters, is explained by an improper technique of mathematical processing of the interferometer data.