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Are SR & GR Considered Experimentally Proven?

  1. Apr 26, 2005 #1

    cj

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    I know a bit about evidence supporting
    special relativity (muon decay, synchronized
    cesium clocks, etc.) and general relativity
    (perihelion of Mercury, etc.).

    BUT - is SR and GR considered "proven" or,
    in the minds of mainstream physicists, is
    the jury still out?
     
  2. jcsd
  3. Apr 26, 2005 #2

    cj

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    I'm contrasting "mainstream" physicists with
    those who contend that the the Moon Landing
    was an elaborate hoax.

    I know there's tons of Web posts and papers
    denouncing SR (seems less against GR) --
    but, again, what is the position of the mainstream:
    firm belief or still debated?
     
  4. Apr 26, 2005 #3
    cj,

    There is no theory in all of physics which is more generally accepted by mainstream physicists than SR.

    Others here who know more about GR than I do can answer that one. But my understanding (such as it is) is that when (if?) everything gets figured out in physics, gravity will look a lot like GR says it does.
     
  5. Apr 26, 2005 #4

    dx

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    Well, GR is accepted enough that many leading theorists consider it the fundamental basis for creating(discovering?) a "Theory of Everything".
     
  6. Apr 26, 2005 #5

    jtbell

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    Strictly speaking, no theory in physics is ever really "proven." In math, we can prove a theorem and be absolutely confident about its validity, provided that we accept the fundamental axioms of mathematics, of course. In physics, all theories are subject to experimental test, and there's always a possibility that a new experiment can provide evidence against even the best-tested theory. The best we can say is that the experimental evidence supports a theory, so far.

    That said, both SR and GR have been extensively tested, and as far as I know, there is no generally-accepted experimental evidence against either of them. There are some experiments that anti-relativity crackpots like to point to, but as far as I know they all have problems with experimental uncertainty (the size of the error bars on the data), or with possible sources of systematic error, or with false assumptions or analysis, and none of them have been reproduced or confirmed by independent experimenters.

    I'm pretty sure that when/if either SR or GR is replaced by a newer, more general theory, the anti-relativity crackpots will like the new theory even less! :rofl:
     
  7. Apr 26, 2005 #6

    Nereid

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    AFAIK, the only theories which compete with GR (SR is simply a 'special case' of GR) either differ from GR only in domains we haven't yet explored (e.g. the first Planck second of the universe, black holes; note that Gravity Probe B will put GR's gravitomagnetism predictions through the wringer, and likely eliminate a class of competitor theories, such as Garth's SCC), or explicitly do NOT produce any observational differences (even in principle - these competitors just look at the world in a different way).

    How well has SR been tested? Through its incorporation into quantum electrodynamics, it has now been tested to ~12 decimal places - i.e. the most stringent test of any theory in physics.

    How about GR? Some aspects have been tested to 20 parts per million; others are as yet only poorly tested (perhaps to only 1%).
     
  8. Apr 26, 2005 #7

    DrChinese

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    Yes, SR & GR are generally accepted as pointed out above. A helpful link for SR-related experiments:

    John Baez's FAQ pages
     
  9. Apr 26, 2005 #8

    robphy

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  10. Apr 26, 2005 #9

    Chronos

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    They both work very well. While nothing is ever 'proven', these two are about as close as it gets. There are, however, some fine points in GR that have not been precisely tested as of yet. GPB is putting frame dragging and precession to the most stringest test ever devised [albeit frame dragging is pretty much in the bag after the incidental observations of LAGEOS]. The least well tested, and one of the more exotic predictions of GR is gravity waves. There is indirect evidence from orbital decay of binary neutron stars, but gravity waves have never been directely detected [they are pretty weak]. LIGO will be the test eveyone has been waiting for.
     
    Last edited: Apr 26, 2005
  11. Apr 26, 2005 #10

    DaveC426913

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    How does this compare to the error Newton's classical view of the universe? For example, the solar eclipse observation of gravitiational deflection by Dyson, Eddington, et al. How much did it show Newton's laws to be in error? More than the above?
     
  12. Apr 26, 2005 #11
    Dave,

    I think these percentage errors are:

    (GR prediction - Measurement)/(Measurement)*100%. If that's the case then Newton would have predicted no shift in the star's apparent position during the eclipse, so his prediction would have been off by 100%. GR wins!
     
  13. Apr 26, 2005 #12
    No theory in science is ever proven. Theories are either accepted or rejected but to a certain extent. The closer a theory describes nature and makes accurate predictions the more it is accepted. Thus in science it is well accepted that Earth is a sphere and is not a flat disk as the flat earth society would have us believe.

    In my opinion - I pretty much accept both SR and GR to the accuracy of the domain to which they make predictions and describe nature (I.e. when quantum relativity comes along it will be that which applies to the subatomic/microscopic domain).

    Pete
     
  14. Apr 26, 2005 #13

    Nereid

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    And yours is one of the 'minds' which is 'open' to 'understanding the foundations of [the] theories'?

    Sarcasm aside,
    1) 'proof' doesn't exist in science (as many have already said, in this thread, and elsewhere) - so on what basis do you choose to use the word here?
    2) a great many - perhaps a near certain [all] - PF members and guests are interested in the 'foundations' of theories; would you be so kind as to explain in what sense you feel the 'foundations' of SR and GR are lacking/limited/degenerate/unsatisfactory/inconsistent/{insert your favourite negative here}?
     
  15. Apr 26, 2005 #14
    They sure are. Read the 'Einstein in everyday life'-entry here https://www.physicsforums.com/journal.php?s=&action=view&journalid=13790&perpage=10&page=7

    Just look at the paragraph on relativistic corrections for GPS-systems...

    marlon
     
  16. Apr 26, 2005 #15
    That is an incorrect conclusion. Recall the idea put forth by Dicke. I don't know his theory but I do know its consequences, one of which is the prediction of gravitational redshift on which the GPS system corrections rely on. Yet GR and Dicke's theory are two seperate theories of gravity.

    Pete
     
  17. Apr 26, 2005 #16
    I don't know Dicke's theory and i don't care, in all honesty. In my opinion there is only one theory for the gravitational interaction so far. The successful corrections to GPS-systems thanks to SR are one of the many experimental proofs that SR is correct. I really don't see how you can object against that ? This is just like saying that QM is 'wrong' because of the EPR-paradox. Yet isn't the entire electronic industry the best proof for the fact that QM is correct ???

    regards
    marlon
     
  18. Apr 26, 2005 #17
    The answeres to the question as to what is proven need to be qualified. There is a great deal of experimental evidence that is consistent with SR and GR. As has been pointed out - these results do not prove either theory - each new confirmation increases our confidence, but what is at root is whether these same tests also validate alternative theories. A good example - the test performed by Kennedy and Thorndyke - at the time there were three major contenders that sought to explain the null result of MMx - when K and T performed their experiment they used unequal interferometer arm lenghts - the null result left those theories that proposed both time dilation and space contraction viable - but it falsified those theories that were based upon contraction alone (e.g., the original Lorentz ether theory and the FitzGereld contraction theory). So, no matter how accurate the result, no matter how many decimal places of correspondence between theory and experiment, as in QED, the results can never eliminate a competing theory that predicts the same outcome.
     
    Last edited: Apr 26, 2005
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