Relativity

Here is a repository of links and publications on the topic of Relativity.

Airy’s failure

  • “On a supposed alteration in the amount of Astronomical Aberration of Light, produced by the passage of the Light through a considerable thickness of Refracting Medium”
  • Published 1871
  • Direct PDF download: George Airy 1871
  • Conclusion: “I think myself justified in concluding that the hypothesis of Professor Klinkerfues is untenable.”
  • “Klinkerfues…inferred that the angle of refraction would be influenced by the motion of the earth, and he attempted to detect the inferred effect.” -Historical Studies in the Physical Sciences, Volume 7
  • This experiment did not detect æther.
  • However, taken in isolation, ignoring all previous evidence of earth’s rotation, one could suggest, if there was æther, it was not in motion relative to the earth.
  • Nothing about the motion of the earth or the existence of æther can be concluded from this experiment.

 Michelson-Morely

  • “On the Relative Motion of the Earth and the Luminiferous Ether”
  • Published 1887
  • Direct PDF download: Michelson Morely 1887
  • Conclusion: Unable to measure relative motion between the earth and the luminiferous ether.
  • This did not conclude there was æther.  However, taken in isolation, ignoring all previous evidence of earth’s rotation, one could suggest, if there was æther, it was not in motion relative to the earth.
  • Nothing about the motion of the earth or the existence of æther can be concluded from this experiment.
  • This was refined in 1926
    • “A REFINEMENT OF THE MICHELSON-MORLEY EXPERIMENT”
    • Direct PDF Download: Michelson-Morely refined 1926
    • By Roy J. Kennedy
    • California Institute of Technology
    • September 30, 1926
    • This experiment was able to measure to a much high level than the original.
    • Conclusion: “The result was perfectly definite. There was no sign of a shift depending on the orientation.”
    • The conclusion is the same as the original experiment.

Eddington 1919

  • “A determination of the deflection of light by the sun’s gravitational field, from observations made at the total eclipse of May 29, 1919”
  • This experiment confirmed that the mass of the sun bent spacetime such that stars behind the sun were visible.
  • From the paper: “Thus the results of the expeditions to Sobral and Principe can leave little doubt that a deflection of light takes place in the neighbourhood of the sun and that it is of the amount demanded by Einstein’s generalised theory of relativity, as attributable to the sun’s gravitational field.”
  • https://doi.org/10.1098/rsta.1920.0009
  • Direct PDF Download: eddington-1919

Michelson-Gale

  • “The Effect of the Earth’s Rotation on the Velocity of Light”
  • Published 1925
  • Direct PDF download: Michelson Gale 1925
  • Measured earth’s rotation from latitude 41°46′
  • 269 measurements
  • Conclusion: “The displacement of the fringes due to the earth’s rotation was measured on many different days, with complete readjustments of the mirrors, with the reflected image sometimes on the right and sometimes on the left of the transmitted image, and by different ob­servers.”
  • Measured rotation of the earth in agreement with the predictions.
  • If one were to attempt to attribute the rotation to æther, it could only be done by directly contradicting Michelson-Morely and Airey’s Failure.  This is because if you reinterpret those to suggest æther exists, those experiments require that the æther does not move in relation to the surface of the earth.  This experiment requires that the æther moves in relation to the surface of the earth.

Kennedy-Thorndike

Ives–Stilwell

Pound–Rebka

Hafele–Keating

  • “Around-the-World Atomic Clocks: Predicted Relativistic Time Gains”
  • Published in 1972
  • https://www.jstor.org/stable/1734833
  • Direct PDF Download of predictions: Hafele–Keating Predicted 1972
  • Direct PDF Download of observations: Hafele–Keating Observed 1972
  • This experiment tested the predicted time dilation according to the theory of relativity.
  • Note: Cesium clocks are accurate to 0.00000000000002 seconds, or 10-14.  A nanosecond is 0.000000001 seconds, or 10-9.
  • Four cesium beam atomic clocks were flown around the world twice.  Eastward, then westward.
  • Prediction: “From the actual flight paths of each trip, the theory predicts that the
    flying clocks, compared with reference clocks at the U.S. Naval Observatory, should have lost 40 +/- 23 nanoseconds during the eastward trip, and should have gained 275 +/- 21 nanoseconds during the westward trip.”
  • Observation: “Relative to the atomic time scale of the U.S. Naval Observatory, the flying clocks lost 59 +/- 10 nanoseconds during the eastward trip and gained 273 +/- 7 nanoseconds during the westward trip, where the errors are the corresponding standard deviations”
  • Conclusion: “In conclusion, we have shown that the effects of travel on the time recording behavior of macroscopic clocks are in reasonable accord with predictions of the conventional theory of relativity, and that they can be observed in a straightforward and unambiguous manner with relatively inexpensive commercial jet flights and commercially available cesium beam clocks.”
  • Third-party writeup on the experiment:

Scout Rocket Experiment

  • “Test of Relativistic Gravitation with a Space-Borne Hydrogen Maser”
  • Performed 1976
  • Published 1980
  • According to the general theory of relativity, at higher altitude a clock should run faster.
  • “The results of a test of general relativity with use of a hydrogen maser frequency standard in a spacecraft launched nearly vertically upward to 10000 km are reported. The agreement of the observed relativistic frequency shift with prediction is at the 70 * 10^-6 level.”
  • A hydrogen-maser clock was flown on a rocket to an altitude of about 10,000 km and its frequency compared to a similar clock on the ground. At this height, a clock should run 4.5 parts in 1010 faster than one on the Earth. During two hours of free fall from its maximum height, the rocket transmitted timing pulses from a maser oscillator which acted as a clock and which was compared with a similar clock on the ground. This result confirmed the gravitational time dilation relationship to within 0.01%.
  • https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.45.2081
  • Direct PDF Download: scout-rocket-1980

Test of Time Dilation Using Stored Li+ Ions as Clocks at Relativistic Speed

  • Enhancement of Ives-Stilwell using Lithium atoms moving at one third the speed of light.
  • Summary: “We present the concluding result from an Ives-Stilwell-type time dilation experiment using 7Li+ ions confined at a velocity of β = v/c = 0.338 in the storage ring ESR at Darmstadt.”
  • http://dx.doi.org/10.1103/PhysRevLett.113.120405

Neutrino Interferometry for High-Precision Tests of Lorentz Symmetry with IceCube

  • Published in 2017
  • Direct PDF Download: Neutrino Interferometry for High-Precision Tests of Lorentz Symmetry with IceCube 2017
  • This experiment attempted to find a violation of Lorentz symmetry.  They did not find evidence of violation, thus adding confirmation to Lorentz symmetry.
  • “We use high-energy atmospheric neutrinos observed at the IceCube Neutrino Observatory to search for anomalous neutrino oscillations as signals of Lorentz violation. We find no evidence for such phenomena.”