Changes

In 1972, scientists flew extremely accurate clocks ("atomic clocks") around the world in both directions on commercial airlines, and claimed to observe relativistic time dilation; the eastbound clock gained 273 ns and the westbound clock lost 59 ns, matching the predictions of general relativity to within experimental accuracy.<ref>[http://www.answers.com/topic/hafele-keating-experiment Hafele-Keating Experiment]</ref>  However, the inventor of the atomic clock, Louis Essen, declared that the experiment was inaccurate.<ref>Louis Essen, Electron. Wireless World 94 (1988) 238.</ref>  Dr A. G. Kelly examined the raw data from the experiment and declared it inconclusive.<ref>A. G. Kelly,Reliability of Relativistic Effect Tests on Airborne Clocks, Monograph No.3 Feb.1996, The Institution of Engineers of Ireland, ISBN 1-898012-22-9</ref>  The Nobel Committee chose not to honor this experiment for the significance that was claimed.

In 1972, scientists flew extremely accurate clocks ("atomic clocks") around the world in both directions on commercial airlines, and claimed to observe relativistic time dilation; the eastbound clock gained 273 ns and the westbound clock lost 59 ns, matching the predictions of general relativity to within experimental accuracy.<ref>[http://www.answers.com/topic/hafele-keating-experiment Hafele-Keating Experiment]</ref>  However, the inventor of the atomic clock, Louis Essen, declared that the experiment was inaccurate.<ref>Louis Essen, Electron. Wireless World 94 (1988) 238.</ref>  Dr A. G. Kelly examined the raw data from the experiment and declared it inconclusive.<ref>A. G. Kelly,Reliability of Relativistic Effect Tests on Airborne Clocks, Monograph No.3 Feb.1996, The Institution of Engineers of Ireland, ISBN 1-898012-22-9</ref>  The Nobel Committee chose not to honor this experiment for the significance that was claimed.

==Experimental and Observational Evidence Confirming Relativity==

==Experimental and Observational Evidence Confirming Relativity==

*Another prediction of special relativity was time dilation in rapidly moving objects.  This effect was most famously verified in the anomalously slow decay of relativistic cosmic muons.<ref>Some have suggested that other explanations are possible for this effect.  We are trying to track this down.</ref>  Time dilation has since been verified many times, and is routinely taken into account in all high-energy nuclear physics experiments, as in Hadron collision experiments.<ref>Experiments specifically designed to check dilation are rarely conducted any more.</ref>

*Another prediction of special relativity was time dilation in rapidly moving objects.  This effect was most famously verified in the anomalously slow decay of relativistic cosmic muons.<ref>Some have suggested that other explanations are possible for this effect.  We are trying to track this down.</ref>  Time dilation has since been verified many times, and is routinely taken into account in all high-energy nuclear physics experiments, as in Hadron collision experiments.<ref>Experiments specifically designed to check dilation are rarely conducted any more.</ref>

As the 20th century progressed, tests of general relativity were proposed.

 

*The first of these was famously tested during a total eclipse in 1919.  That test was somewhat muddled by an incorrect initial calculation, by several people including Einstein himself, of what the effect would be, and some "cherry picking" of the data to be used.<ref>''Einstein's Luck'', John Waller, Oxford University Press, ISBN 0-19-860719-9</ref>  The data selection could be considered "manipulation" or "fudging", by a person (Arthur Eddington) who had a personal stake in the outcome.  His analysis techniques would not pass muster today.  The announcement of this test, flawed though it was, made Einstein world-famous.<ref>[http://einstein.stanford.edu/Library/images/lightsAllAskewBig.jpg The New York Times, Nov. 10, 1919]</ref><ref>[https://www.worldbooklearning.com/how-did-an-eclipse-help-make-albert-einstein-famous/ How did an eclipse help make Albert Einstein famous]</ref><ref>[https://blog.supplysideliberal.com/post/44934715350/how-albert-einstein-became-a-celebrity How Albert Einstein became a celebrity]</ref><ref>[https://www.sciencealert.com/general-relativity-experiment-confirms-accuracy-for-galaxies "The public's mind was blown by the results, effectively turning Albert Einstein into a household name and cementing the concept of general relativity into physics books."]</ref>

 

:It should be noted that pre-relativistic (Newtonian) physics may also predict a bending, of half the observed value, depending on whether one uses the 17th century "corpuscular" formulation or the 19th century "wave" formulation.

 

:Relying on the usual assumptions&mdash;Newtonian mechanics, Galilean relativity, conservation of energy and momentum, the universality of the speed of light (that is, special relativity), the Equivalence Principle, and the geodesic equation in empty space (that is, general relativity), and the proper calibration of the instruments, observations of later eclipses, and the observations of quasar 3C273, confirm predictions of the theory.

 

 

*The second "classical" test of general relativity was the advance of the perihelion of the orbit of Mercury.  There are many complex effects contributing to this, including gravitational perturbations from other planets and the effect of the oblateness of the Sun.  These are hard to calculate accurately, but, by 1900 it was known quite accurately that there was an "anomalous" precession, that is, a precession beyond all other known effects, of 43 arc seconds per century.  This is a very tiny effect, but astronomical measurements were sufficiently accurate by that time to show it clearly.

 

:No Nobel Prize was was awarded for this.

*One important "classical" test of general relativity was the advance of the perihelion of the orbit of Mercury.  There are many complex effects contributing to this, including gravitational perturbations from other planets and the effect of the oblateness of the Sun.  These are hard to calculate accurately, but, by 1900 it was known quite accurately that there was an "anomalous" precession, that is, a precession beyond all other known effects, of 43 arc seconds per century.  This is a very tiny effect, but astronomical measurements were sufficiently accurate by that time to show it clearly.

*One important "classical" test of general relativity was the advance of the perihelion of the orbit of Mercury.  There are many complex effects contributing to this, including gravitational perturbations from other planets and the effect of the oblateness of the Sun.  These are hard to calculate accurately, but, by 1900 it was known quite accurately that there was an "anomalous" precession, that is, a precession beyond all other known effects, of 43 arc seconds per century.  This is a very tiny effect, but astronomical measurements were sufficiently accurate by that time to show it clearly.