Michelson-Morley Experiment

The Michelson–Morley experiment was first performed in 1887 by Albert A. Michelson and Edward W. Morley. Its purpose was to compare the speed of light in perpendicular directions, in an attempt to detect the relative motion of matter through the stationary luminiferous aether by using the rotation of the earth to create interference bands of light for the study.

Morley wrote to his father that the purpose of the experiment was “to see if light travels with the same velocity in all directions.”1

The surprising and shocking result of this experiment is that the earth did not measurably rotate at all, in contradiction to all expectations and the accepted astronomical model. Michelson and Morley found that a light beam discharged in the direction of the Earth’s assumed motion showed virtually no difference in speed from a light beam discharged north to south or south to north. In other words, the experiment failed to detect the Earth moving in or against space, of whatever space was understood to consist.

Michelson and Morley repeated the experiment many times, and in many different horizontal axial positions and configurations, all with a null result. The earth was seen to be motionless. The experiment has been referred to as "the moving-off point for the theoretical aspects of the Second Scientific Revolution" and directly influenced the creation of Albert Einstein's Theory of General Relativity.

The Theory of General Relativity subsequently found favor among scientific circles because its model was designed to seemingly explain the motionless earth result of the Michelson-Morley experiment. This allowed the theory of the earth's rotation to survive direct contradicting experimental evidence and encouraged, perhaps forced, the adoption of GR as the accepted model of space for Heliocentricism.

http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/mmhist.html

"Although repeated over the next 40 years with ever greater precision and the same negative result, this 1887 experiment is pointed to as one of the experimental foundations of relativity, and earned Michelson the Nobel Prize in 1907."

1 Letter dated April 17, 1887, in the Edward W. Morley Papers, Library of Congress, as cited  in  Dorothy  Michelson Livingston’s Master of Light: A Biography of Albert Michelson, New York, Charles Scribner, 1973, p.126.

=Description and Result=

Material from a York University course provides a good summary of the Michelson-Morley experiment and its result. Below are selected slides that tell the story. Interested readers should feel free to go through the entire slide deck.

Class Description Full Slideshow



=Peer Reviews and Repetitions=

Since 1887 the Michelson-Morley experiment has been repeated and verified on a number of occasions.

2009 Repetition in Germany
https://physicsworld.com/a/michelson-morley-experiment-is-best-yet/

Michelson–Morley experiment is best yet

"Physicists in Germany have performed the most precise Michelson-Morley experiment to date, confirming that the speed of light is the same in all directions. The experiment, which involves rotating two optical cavities, is about 10 times more precise than previous experiments – and a hundred million times more precise than Michelson and Morley’s 1887 measurement."

=Influence of the M-M Experiment on General Relativity=

Historical Marker
In Cleveland, Ohio, there is a Michelson-Morley Historical Marker located just outside the science building on the Case Western Reserve University campus which provides the following:

"The Michelson-Morley Experiment, conducted at the Western Reserver University in July 1887, provides the earliest direct evidence that would later support Albert Einstein's theory of relativity. Albert A. Michelson, professor of physics at the Case School of Applied Sciences, and Edward Morley, professor of chemistry at Western Reserve University, tested the prevailing scientific theory that light waves travel faster downwind and slower against an upwind as they travel faster through a substance once thought to permeate space called aether. Finding no differences in the velocity of light waves traveling in different directions with respect to Earth's motion around the sun, the experiment's results baffled a generation of scientists until Einstein solved the riddle by formulating a new understanding of time and space. In 1907, Michelson, then head of the physics department at the University of Chicago, became the first American scientist to earn the Nobel Prize: he did so in physics."

Why General Relativity was Accepted
Why Was Relativity Accepted? By Stephen G. Brush

Full Text: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.535.1670&rep=rep1&type=pdf

An interesting analysis on why Relativity was accepted in science. The author concludes that much of why it was accepted is because it was a world-model which purported to explain the Michelson-Morley experimental result of a motionless non-rotating earth. Another top reason was because of an underlying desire for a unified, elegant physical theory

The author provides quotes by the scientists of the day, identifying the Michelson-Morely null result as a primary factor.

Remarks by Prominent Physicists
"José Sánchez-Ron [a prominent Spanish physicist] suggests that G.A. Schott and other British physicists were interested in relativity because it offered a way to deal with problems arising from the new atomic physics, in which the magnetic interactions of electrons and their behavior at very high speeds needed to be better understood. Sánchez-Ron also points to the interest of these physicists in symmetry considerations. But the most explicit statement he quotes about the reason for accepting relativity is that of an anonymous reviewer of Ludwik Silberstein’s 1914 book: ‘without the result of Michelson and Morley’s experiment there would be no justification for the theory at all... [It] will only be when further experimental data of a crucial kind are obtained that the theory will run much chance of becoming definitely accepted as scientific knowledge.’" "In 1907, K.K. Baumgart supported the‘‘Lorentz-Einstein theory’’ because it was compatible with the negative result of the Michelson-Morley experiment" "Dirac [a famous English theoretical physicist] stated that he first learned about relativity theory when it was widely publicized in England after World War I by Eddington. His initial interest in the theory was captured by the experimental evidence – Michelson-Morley experiment, Mercury’s orbit, and light bending."

"Langevin [a famous French physicist] tried to persuade the Collège de France to invite Einstein to lecture in Paris, and finally succeeded in 1922; the result was a flurry of popular interest in relativity. After Einstein’s visit Langevin decided that relativity is supported by experiments such as that of Michelson and Morley."

Statistical Tables
The author provides three statistical analysis tables for why Relativity was accepted, focusing on Empirical reasons, Social-Psychological reasons, and Aesthetic-Mathematical reasons.



Abbreviation Reference

Empirical MiMo — negative result of Michelson-Morley experiment EtDr — failure of ether drift experiments ElMa — variation of electron mass with velocity ElCh — variation of electron charge with velocity VeLi — velocity of light from terrestrial and celestial sources is the same BoOr — correction of orbits and energy levels in Bohr model of atom LiBe — light-bending observations MePe — Advance of Mercury Perihelion GrRe — Gravitational redshift of spectral lines

Social-Psychological NSTh — rejection of absolute space and time is consistent with neoscholastic theology MoSc — association with ‘‘modern’’ science PoSt — relativism of political structures, attractive to anit-democratic ideologues CoIC — acquire prestige for comprehending the incomprehensible GePh — respect for authority of German physics

Aesthetic-Mathematical Math — mathematical aspects of the theory Unif — desire for a unified, elegant physical theory EMWV — connection with electromagnetic worldview NEGe — connection with Lobachevskii’s non-Euclidean geometry