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 shift and diffuse to create interference bands of light for study.

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 repeated the experiment many times, and in many different 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 adoption of GR as the accepted model of space.

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."

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 MM Experiment on General Relativity

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 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 famous 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