Timeline of luminiferous aether
Encyclopedia
The timeline
Timeline
A timeline is a way of displaying a list of events in chronological order, sometimes described as a project artifact . It is typically a graphic design showing a long bar labeled with dates alongside itself and events labeled on points where they would have happened.-Uses of timelines:Timelines...

 of luminiferous aether
Luminiferous aether
In the late 19th century, luminiferous aether or ether, meaning light-bearing aether, was the term used to describe a medium for the propagation of light....

begins in the late 19th century with the concept of luminiferous aether ("light-bearing aether
Luminiferous aether
In the late 19th century, luminiferous aether or ether, meaning light-bearing aether, was the term used to describe a medium for the propagation of light....

"), or ether, as a medium
Transmission medium
A transmission medium is a material substance that can propagate energy waves...

 for electromagnetic
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...

 propagation. The aether was assumed to exist
Existence
In common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity...

 for much of the 19th century—until the Michelson-Morley experiment
Michelson-Morley experiment
The Michelson–Morley experiment was performed in 1887 by Albert Michelson and Edward Morley at what is now Case Western Reserve University in Cleveland, Ohio. Its results are generally considered to be the first strong evidence against the theory of a luminiferous ether and in favor of special...

 returned the famous "null result". Further experiments were in general agreement and by the 1920s the aether was mostly assumed not to exist.

Early experiments

4th-century BC – Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

 publishes Physics
Physics (Aristotle)
The Physics of Aristotle is one of the foundational books of Western science and philosophy...

. He was one of the first to publicly hypothesize as to the nature of light, proposing that it was a disturbance in the element air, hence it was a wave-like phenomenon.
1704 – Isaac Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

 publishes Opticks
Opticks
Opticks is a book written by English physicist Isaac Newton that was released to the public in 1704. It is about optics and the refraction of light, and is considered one of the great works of science in history...

, in which he proposes a particle theory of light. This had trouble explaining refraction
Refraction
Refraction is the change in direction of a wave due to a change in its speed. It is essentially a surface phenomenon . The phenomenon is mainly in governance to the law of conservation of energy. The proper explanation would be that due to change of medium, the phase velocity of the wave is changed...

, so he adds a "fudge factor", claiming that an "Aethereal Medium" is responsible for this effect, and going further to suggest it might be responsible for other physical effects such as heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

.
1727 – James Bradley
James Bradley
James Bradley FRS was an English astronomer and served as Astronomer Royal from 1742, succeeding Edmund Halley. He is best known for two fundamental discoveries in astronomy, the aberration of light , and the nutation of the Earth's axis...

 measures stellar aberration for the first time, proving (again) that light has a finite speed as well as that the Earth is moving.
1818 – Augustin Fresnel introduces the wave theory of light, which proposes light is a transverse wave travelling in an aether, thereby explaining how polarization can exist. It is important to note that both Newton's particle theory and Fresnel's wave theory both assume an aether exists, albeit for different reasons. From this point on, no one even seems to question its existence.
1820 – Discovery of Siméon Poisson's "Bright Spot", supporting the Wave Theory.
1830 – Fresnel develops a formula for predicting and measuring aether dragging by massive objects, based on a coupling constant. Such dragging seems to be at odds with aberration however, which would require the Earth not to drag the aether in order to be visible.
George Gabriel Stokes
George Gabriel Stokes
Sir George Gabriel Stokes, 1st Baronet FRS , was an Irish mathematician and physicist, who at Cambridge made important contributions to fluid dynamics , optics, and mathematical physics...

 becomes a champion of the dragging theory.
1851 – Armand Fizeau carries out his famous experiment with light travelling through moving water. He measures fringing due to motion of the water, perfectly in line with Fresnel's formula. However he sees no effect due to the motion of the Earth, although he does not comment on this. Nevertheless this is seen as very strong evidence for aether dragging.
1868 – Martinus Hoek carries out an improved version of Fizeau's using an interferometer experiment with one arm in water. He sees no effect at all, and cannot offer an explanation as to why his experiment is so at odds with Fizeau's.
1871 – George Biddell Airy
George Biddell Airy
Sir George Biddell Airy PRS KCB was an English mathematician and astronomer, Astronomer Royal from 1835 to 1881...

 re-runs Bradley's experiment with a telescope filled with water. He too sees no effect. It appears that aether is not dragged by mass.
1873 – James Clerk Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

 publishes his Treatise on Electricity and Magnetism.
1878 to 1880 – Maxwell suggests absolute velocity of Earth in aether may be optically detectable.
1881 – Albert Abraham Michelson
Albert Abraham Michelson
Albert Abraham Michelson was an American physicist known for his work on the measurement of the speed of light and especially for the Michelson-Morley experiment. In 1907 he received the Nobel Prize in Physics...

 publishes his first interferometer experiments, using the device for the measurement of extremely small distances.
Hendrik Antoon Lorentz finds Michelson's calculation have errors (i.e., doubling of the expected fringe shift error).
1882 – Michelson acknowledges his interpretation errors.

Crisis

1887 – the Michelson-Morley experiment
Michelson-Morley experiment
The Michelson–Morley experiment was performed in 1887 by Albert Michelson and Edward Morley at what is now Case Western Reserve University in Cleveland, Ohio. Its results are generally considered to be the first strong evidence against the theory of a luminiferous ether and in favor of special...

 (MMX) produces the famous null result. A small drift is seen, but it is too small to support any "fixed" aether theory, and is so small that it might be due to experimental error.
Many physicists dust off Stokes' work, and dragging becomes the "standard solution"
1887 to 1888 – Heinrich Hertz verifies the existence of electromagnetic waves.
1889 – George FitzGerald
George FitzGerald
George Francis FitzGerald was an Irish professor of "natural and experimental philosophy" at Trinity College in Dublin, Ireland, during the last quarter of the 19th century....

 proposes the Contraction Hypothesis, which suggests that the measurements are null due to changes in the length in the direction of travel through the aether.
1892 – Oliver Lodge demonstrates that aether drag is invisible around rapidly moving celestial bodies.
1895 – Lorentz proposes independently the Contraction Hypothesis.
1902 to 1904 – Morley and Morley conduct a number of MM experiments with a 100 ft interferometer, producing the null result.
1902 to 1904 – Lord Rayleigh and DeWitt Bristol Brace
DeWitt Bristol Brace
DeWitt Bristol Brace was an US-American physicist who was known for his optical experiments, especially as regards the relative motion of Earth and the luminiferous aether.-Life and work:...

 found no signs of double refraction (due to Fitzgerald-Lorentz Contraction) of moving bodies in the aether.
1903 – the Trouton-Noble experiment
Trouton-Noble experiment
The Trouton–Noble experiment attempted to detect motion of the Earth through the luminiferous aether, and was conducted in 1901–1903 by Frederick Thomas Trouton and H. R. Noble...

, based on an entirely different concept using electrical forces, also produces the null result
1905 – Miller and Morley's experiment data is published. Test of the Contraction Hypothesis has negative results. Test for aether dragging effects produces null result.
1908 – the Trouton-Rankine experiment
Trouton-Rankine experiment
The Trouton–Rankine experiment was an experiment designed to measure if the Lorentz–FitzGerald contraction of an object according to one frame produced a measurable effect in the rest frame of the object, so that the ether would act as a "preferred frame"...

, another experiment based on electrical effects, does not detect the Fitzgerald-Lorentz Contraction.

Change

1904 – Hendrik Lorentz
Hendrik Lorentz
Hendrik Antoon Lorentz was a Dutch physicist who shared the 1902 Nobel Prize in Physics with Pieter Zeeman for the discovery and theoretical explanation of the Zeeman effect...

 publishes a new theory of moving bodies, without discarding the stationary (electromagnetic) ether concept.
1905 – Henri Poincaré
Henri Poincaré
Jules Henri Poincaré was a French mathematician, theoretical physicist, engineer, and a philosopher of science...

 shows that Lorentz's theory fulfills the principle of relativity, and publishes the Lorentz transformations. His model was still based on Lorentz's ether, but he argues that this aether is perfectly undetectable.
1905 – Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

 publishes an observationally equivalent theory, but complete with a derivation from principles alone (leaving the ether aside). Einstein also emphasized that this concept implies the relativity of space and time. He later labelled it special relativity
Special relativity
Special relativity is the physical theory of measurement in an inertial frame of reference proposed in 1905 by Albert Einstein in the paper "On the Electrodynamics of Moving Bodies".It generalizes Galileo's...

.
1908 – Trouton-Rankine experiment
Trouton-Rankine experiment
The Trouton–Rankine experiment was an experiment designed to measure if the Lorentz–FitzGerald contraction of an object according to one frame produced a measurable effect in the rest frame of the object, so that the ether would act as a "preferred frame"...

 shows that length contraction
Length contraction
In physics, length contraction – according to Hendrik Lorentz – is the physical phenomenon of a decrease in length detected by an observer of objects that travel at any non-zero velocity relative to that observer...

 of an object according to one frame does not produce a measurable change of resistance in the object's rest frame
1913 – Georges Sagnac
Georges Sagnac
Georges Sagnac was a French physicist who lent his name to the Sagnac effect, a phenomenon which is at the basis of interferometers and ring laser gyroscopes developed since the 1970s. Sagnac died at Meudon-Bellevue....

 uses a rotating MMX device and receives a clearly positive result. The so-called Sagnac effect
Sagnac effect
The Sagnac effect , named after French physicist Georges Sagnac, is a phenomenon encountered in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called ring interferometry. A beam of light is split and the two beams are made to follow a trajectory in...

 was considered excellent evidence for aether at the time, but was later explained via general relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...

. Good explanations based on SR also exist.
1914 – Walther Zurhellen uses observations of binary stars to determine if the speed of light is dependent on movement of the source. His measurements show that it is not to 10−6. This is claimed to be additional evidence against aether dragging.
1915 – Einstein publishes on the general theory of relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...

.
1919 – Arthur Eddington's Africa eclipse expedition is conducted and appears to confirm the general theory of relativity.
1920 – Einstein says that special relativity does not require rejecting the aether, and that the gravitational field of general relativity may be called aether, to which no state of motion can be attributed.
1921 – Dayton Miller
Dayton Miller
Dayton Clarence Miller was an American physicist, astronomer, acoustician, and accomplished amateur flautist...

 conducts aether drift experiments at Mount Wilson
Mount Wilson (California)
Mount Wilson is one of the better known peaks in the San Gabriel Mountains, part of the Angeles National Forest in Los Angeles County, California. It is the location of the Mount Wilson Observatory and has become the astronomical center of Southern California with and telescopes, and and tall...

. Miller performs tests with insulated and non-magnetic interferometers and obtains positive results.
1921 to 1924 – Miller conducts extensive tests under controlled conditions at Case University.
1924 – Miller repeats his experiments at Mount Wilson and yields a positive result.
Rudolf Tomascheck uses stars for his interferometer light source, getting the null result.
1925 – the Michelson-Gale-Pearson experiment
Michelson-Gale-Pearson experiment
The Michelson–Gale–Pearson experiment is a modified version of the Michelson-Morley experiment and the Sagnac-Interferometer. It measured the Sagnac effect due to Earth's rotation, and thus tests the theories of special relativity and luminiferous ether along the rotating frame of...

 produces a positive result while attempting to detect the effect of Earth's rotation on the velocity of light. The significance of the experiment remains debated to this day, but this planetary Sagnac effect is measured by ring laser gyros and taken into account by the GPS system.
1925 April – Meeting of the National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...

.
Arthur Compton
Arthur Compton
Arthur Holly Compton was an American physicist and Nobel laureate in physics for his discovery of the Compton effect. He served as Chancellor of Washington University in St. Louis from 1945 to 1953.-Early years:...

 explains the problems with the Stokes aether drag solution.
Miller presents his positive results of the aether drag.
1925 December – American Association for the Advancement of Science
American Association for the Advancement of Science
The American Association for the Advancement of Science is an international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsibility, and supporting scientific education and science outreach for the...

 meeting.
Miller proposes two theories to account for the positive result. One consists of a modified aether theory, the other a slight departure from the Contraction Hypothesis.
1926 – Roy J. Kennedy produces a null result on Mount Wilson
Auguste Piccard
Auguste Piccard
Auguste Antoine Piccard was a Swiss physicist, inventor and explorer.-Biography:Piccard and his twin brother Jean Felix were born in Basel, Switzerland...

 and Ernest Stahel produce a null result on Mont Rigi.
1927 – Mount Wilson conference.
Miller talks of partial entrainment
Michelson talks about aether drag and altitude differential effects
K. K. Illingworth produces a null result using a clever version of the MMX with a step in one mirror that dramatically improves resolution. The resolution is so good that most partial entrainment systems can be eliminated.
1929 – Michelson and F. G. Pease perform the Pearson experiment and produce a null result.
1930 – Georg Joos
Georg Joos
Georg Jakob Christof Joos was a German theoretical physicist. He wrote Lehrbuch der theoretischen Physik, first published in 1932 and one of the most influential theoretical physics textbooks of the 20th Century.-Education:Joos began his higher education in 1912 at the Technische Hochschule...

 produces a null result using an extremely accurate interferometer placed entirely in vacuum.
1932 – the Kennedy-Thorndike experiment
Kennedy-Thorndike experiment
The Kennedy–Thorndike experiment first conducted in 1932, is a modified form of the Michelson–Morley experimental procedure, and tests special relativity....

 uses an interferometer with arms of different lengths and not at right angles. They measure over several seasons and record on photographs to allow better post-measurement study. The Kennedy Thorndike experiment becomes one of the fundamental tests for SR, proving the independence of light speed wrt to the speed of the emitting source. The other two fundamental tests are Michelson-Morley experiment
Michelson-Morley experiment
The Michelson–Morley experiment was performed in 1887 by Albert Michelson and Edward Morley at what is now Case Western Reserve University in Cleveland, Ohio. Its results are generally considered to be the first strong evidence against the theory of a luminiferous ether and in favor of special...

 (proves light speed isotropy) and Ives-Stilwell experiment
Ives-Stilwell experiment
The Ives–Stilwell experiment exploits the transverse Doppler effect . This was the first direct, quantitative confirmation of the time dilation factor. Together with the Michelson–Morley and Kennedy–Thorndike experiments, it forms one of the fundamental tests of special relativity theory...

 (proves time dilation)
1934 – Georg Joos
Georg Joos
Georg Jakob Christof Joos was a German theoretical physicist. He wrote Lehrbuch der theoretischen Physik, first published in 1932 and one of the most influential theoretical physics textbooks of the 20th Century.-Education:Joos began his higher education in 1912 at the Technische Hochschule...

 publishes on the Michelson-Gale-Pearson experiment
Michelson-Gale-Pearson experiment
The Michelson–Gale–Pearson experiment is a modified version of the Michelson-Morley experiment and the Sagnac-Interferometer. It measured the Sagnac effect due to Earth's rotation, and thus tests the theories of special relativity and luminiferous ether along the rotating frame of...

, stating that it is improbable that aether would be entrained by translational motion and not by rotational motion.
1935 – Hammar experiment
Hammar experiment
The Hammar experiment was an experiment designed by Gustaf Wilhelm Hammar to test the aether drag hypothesis.-Overview:In 1903 the Trouton-Noble experiment, and later the Trouton-Rankine experiment in 1908, presented controversial evidence against the theory of a medium for light propagation known...

 disproves aether entrainment
1951 – Paul Dirac
Paul Dirac
Paul Adrien Maurice Dirac, OM, FRS was an English theoretical physicist who made fundamental contributions to the early development of both quantum mechanics and quantum electrodynamics...

 writes that currently-accepted quantum field theory requires an aether, although he never formulated this theory completely.

Debate slows

1955 – R. S. Shankland, S. W. McCuskey, F. C. Leone, and G. Kuerti performed an analysis of Miller's results and explained them as stemming from systematic errors (Shankland's explanation is now widely accepted).
1958 – Cedarholm, Havens, and Townes use two maser
Maser
A maser is a device that produces coherent electromagnetic waves through amplification by stimulated emission. Historically, “maser” derives from the original, upper-case acronym MASER, which stands for "Microwave Amplification by Stimulated Emission of Radiation"...

s frequency locked to each other and send the light in two directions. They receive the null result. The experiment is not as precise as earlier light-based MMX experiments, but demonstrates a novel setup that would become much more accurate in the future.
1964 Jaseja, Javan, Murray and Townes repeat the earlier experiment with newer and much more precise masers.
1969 – Shamir and Fox repeat the MMX experiment with the "arms" in acrylic glass
Acrylic glass
Poly is a transparent thermoplastic, often used as a light or shatter-resistant alternative to glass. It is sometimes called acrylic glass. Chemically, it is the synthetic polymer of methyl methacrylate...

 waveguides and a highly stable laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

 as the source. The experiment should detect a shift as small as ~0.00003 of a fringe, and none is measured.
1972 – R. S. Shankland admits he would not likely have given the effort to question Dayton Miller's work had it not been for Albert Einstein's "interest and encouragement."
1973 – Trimmer finds a null result in a triangular interferometer with one leg in glass.
1977 – Brecher repeates Zurhellen's experiment with binary pulsars, showing no difference in light speed to 2*10−9
1979 Brillet and Hall use the Townes setup with highly accurate lasers, demonstrating no drift to 3 parts in 1015. Interestingly the experiment also demonstrates a leftover 17 Hz signal, but the authors assume it is linked to the laboratory.
1984 – Torr and Kolen find a cyclic phase shift between two atomic clock
Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...

s, but the distance between is relatively short (0.5 km) and they're clocks of the less-precise rubidium type
1988 – Gagnon et al. measure one way light speed and detect no anisotropy
1990 – Hils and Hall repeat the Kennedy-Thorndike experiment with lasers, taking measurements over the period of a year. They find no shifting in 2 10−13

Krisher et al., Phys. Rev. D, 42, No. 2, pp. 731–734, (1990) use two hydrogen masers fixed to the earth and separated by a 21 km fiber-optic link to look for variations in the phase between them. They put an upper limit on the one-way linear anisotropy of 100 m/s.
1991 – Over a six-month period, Roland DeWitte finds, over a 1.5 km underground coaxial cable
Coaxial cable
Coaxial cable, or coax, has an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis...

, a cyclic component in the phase drift between higher-precision cesium-beam clocks on more-or-less the same meridian
Meridian (geography)
A meridian is an imaginary line on the Earth's surface from the North Pole to the South Pole that connects all locations along it with a given longitude. The position of a point along the meridian is given by its latitude. Each meridian is perpendicular to all circles of latitude...

; the period equals the sidereal day http://www.lns.cornell.edu/spr/1998-12/msg0013719.htmlhttp://www.scieng.flinders.edu.au/cpes/people/cahill_r/HPS16.pdf
2003 – Holger Mueller and Achim Peters carry out a Modern Michelson-Morley Experiment using Cryogenic Optical Resonators at Humboldt University, Berlin. They find no shifting in 10−15 http://link.aps.org/abstract/PRL/v91/e020401

Further reading

  • Banesh Hoffman, Relativity and Its Roots (Freeman, New York, 1983).
  • Michael Janssen, 19th Century Ether Theory, Einstein for Everyone course at UMN
    University of Minnesota
    The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 52,557...

     (2001).
  • Wallace Kantor, Relativistic Propagation of Light (Coronado Press, 1976), WorldCatLibraries.org

Classical references

  • Maxwell, Collected Papers, H. A. Lorentz, Archives Neerlandaises, xxi. 1887, and xxv. 1892
  • Versuch einer Theorie der electrischen und optischen Erscheinungen in bewegten Korpern (Leyden, 1895)
  • "Elektrodynamik " and " Elektronentheorie " in the Encyk. der Math. Wissenschaften, Band v. 13, 14
  • O. Lodge, " On Aberration Problems," Phil. Trans. 1893 and 1897
  • J. Larmor, Phil. Trans. 1894-95-97, and a treatise, Aether and Matter (1900) p. 262
  • P. K. L. Drude
    Paul Karl Ludwig Drude
    Paul Karl Ludwig Drude was a German physicist specializing in optics. He wrote a fundamental textbook integrating optics with Maxwell's theories of electromagnetism.- Education :...

    , A. Schuster, R. W., General physics of the aether;
  • Collected Papers of Lord Rayleigh

See also

  • Electricity
    Electricity
    Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

  • Electricity (History of discovery)
  • Electromagnetism
    Electromagnetism
    Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

  • History of electromagnetism
  • Light
    Light
    Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

  • Light (Wave theory)
  • Luminiferous aether
    Luminiferous aether
    In the late 19th century, luminiferous aether or ether, meaning light-bearing aether, was the term used to describe a medium for the propagation of light....

  • Luminiferous aether (The history of light and aether)
  • Magnetism
    Magnetism
    Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...

  • Magnetic field
    Magnetic field
    A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...


External links and references

  • OCR scan of the aether listing in the 1911 edition encyclopedia page 1 page 2

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