Michelson–Gale–Pearson experiment

Michelson–Gale–Pearson experiment

The Michelson–Gale–Pearson experiment (1925) 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 Earth.

Experiment

The aim, as it was first proposed by Albert Abraham Michelson in 1904 and then executed in 1925, was to find out whether the rotation of the Earth has an effect on the propagation of light in the vicinity of the Earth.[1][2] [3] The Michelson-Gale experiment was a very large ring interferometer, (a perimeter of 1.9 kilometer), large enough to detect the angular velocity of the Earth. Like the original Michelson-Morley experiment, the Michelson-Gale-Pearson version compared the light from a single source (carbon arc) after travelling in two directions. The major change was to replace the two "arms" of the original MM version with two rectangles, one much larger than the other. Light was sent into the rectangles, reflecting off mirrors at the corners, and returned to the starting point. Light exiting the two rectangles was compared on a screen just as the light returning from the two arms would be in a standard MM experiment. The expected fringe shift in accordance with the stationary aether and special relativity was given by Michelson as:

\Delta=\frac{4A\omega\sin\phi}{\lambda c}

where Δ is the displacement in fringes, A the area in square kilometers, ϕ the latitude (41° 46'), c the speed of light, ω the angular velocity of Earth, λ the effective wave-length used. In other words, this experiment was aimed to detect the Sagnac effect due to Earth's rotation.[4][5]

Result

The outcome of the experiment was that the angular velocity of the Earth as measured by astronomy was confirmed to within measuring accuracy. The ring interferometer of the Michelson-Gale experiment was not calibrated by comparison with an outside reference (which was not possible, because the setup was fixed to the Earth). From its design it could be deduced where the central interference fringe ought to be if there would be zero shift. The measured shift was 230 parts in 1000, with an accuracy of 5 parts in 1000. The predicted shift was 237 parts in 1000. According to Michelson/Gale, the experiment is compatible with both the idea of a stationary ether and special relativity.

As it was already pointed out by Michelson in 1904, a positive result in such experiments contradicts the hypothesis of complete aether drag. On the other hand, the stationary ether concept is in agreement with this result, yet it contradicts (with the exception of Lorentz's ether) the Michelson-Morley experiment. Thus special relativity is the only theory which explains both experiments[6]. The experiment is consistent with relativity for the same reason as all other Sagnac type experiments (see Sagnac effect). That is, rotation is absolute in special relativity, because there is no inertial frame of reference in which the whole device is at rest during the complete process of rotation, thus the light paths of the two rays are different in all of those frames, consequently a positive result must occur. It's also possible to define rotating frames in special relativity (Born coordinates), yet in those frames the speed of light is not constant in extended areas any more, thus also in this view a positive result must occur. Today, Sagnac type effects due to Earth's rotation are routinely incorporated into GPS.

References

  1. ^ Michelson, A.A. (1904). "Relative Motion of Earth and Aether". Philosophical Magazine 8 (48): 716–719. 
  2. ^ Michelson, A. A. (1925). "The Effect of the Earth's Rotation on the Velocity of Light, I.". Astrophysical Journal 61: 137. Bibcode 1925ApJ....61..137M. doi:10.1086/142878. 
  3. ^ Michelson, A. A.; Gale, Henry G. (1925). "The Effect of the Earth's Rotation on the Velocity of Light, II.". Astrophysical Journal 61: 140. Bibcode 1925ApJ....61..140M. doi:10.1086/142879. 
  4. ^ Anderson, R., Bilger, H.R., Stedman, G.E. (1994). "Sagnac effect: A century of Earth-rotated interferometers". Am. J. Phys. 62 (11): 975–985. Bibcode 1994AmJPh..62..975A. doi:10.1119/1.17656. 
  5. ^ Stedman, G. E. (1997). "Ring-laser tests of fundamental physics and geophysics". Reports on Progress in Physics 60 (6): 615-688. Bibcode 1997RPPh...60..615S. doi:10.1088/0034-4885/60/6/001. 
  6. ^ Georg Joos: Lehrbuch der theoretischen Physik. 12. edition, 1959, page 448

Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Michelson-Gale-Pearson experiment — The Michelson Gale Pearson experiment (1925) is a modified version of the Michelson Morley experiment and the Sagnac Interferometer which tests the theories of special relativity and luminiferous ether along the rotating frame of Earth. The aim… …   Wikipedia

  • Michelson — may refer to: Albert Abraham Michelson American physicist Robert C. Michelson American roboticist Michelson (asteroid) discovered in 1991 Michelson (crater) on the moon Michelson Gale Pearson experiment, science Michelson interferometer, most… …   Wikipedia

  • Michelson–Morley experiment — Box plots based on data from the 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… …   Wikipedia

  • Michelson-Experiment — Wenn elektromagnetische Wellen an einen ruhenden Äther gebunden wären, müsste man die Eigenbewegung von Erde und Sonne als Ätherwind messen können. Das Michelson Morley Experiment war ein physikalisches Experiment, das von dem deutsch… …   Deutsch Wikipedia

  • Michelson-Morley — Wenn elektromagnetische Wellen an einen ruhenden Äther gebunden wären, müsste man die Eigenbewegung von Erde und Sonne als Ätherwind messen können. Das Michelson Morley Experiment war ein physikalisches Experiment, das von dem deutsch… …   Deutsch Wikipedia

  • Michelson-Morley-Versuch — Wenn elektromagnetische Wellen an einen ruhenden Äther gebunden wären, müsste man die Eigenbewegung von Erde und Sonne als Ätherwind messen können. Das Michelson Morley Experiment war ein physikalisches Experiment, das von dem deutsch… …   Deutsch Wikipedia

  • Michelson Morley — Wenn elektromagnetische Wellen an einen ruhenden Äther gebunden wären, müsste man die Eigenbewegung von Erde und Sonne als Ätherwind messen können. Das Michelson Morley Experiment war ein physikalisches Experiment, das von dem deutsch… …   Deutsch Wikipedia

  • Hughes–Drever experiment — Hughes–Drever experiments (also clock comparison , clock anisotropy , mass isotropy , or energy isotropy experiments) are testing the isotropy of mass and space. As in Michelson–Morley experiments, the existence of a preferred frame of reference …   Wikipedia

  • De Sitter double star experiment — This article is about observing binary stars. For precession of orbiting bodies, see de Sitter precession. de Sitter s double star argument The de Sitter effect was described by de Sitter in 1913 and used to support the special theory of… …   Wikipedia

  • Luminiferous aether — The luminiferous aether: it was hypothesised that the Earth moves through a medium of aether that carries light In the late 19th century, luminiferous aether or ether, meaning light bearing aether, was the term used to describe a medium for the… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”