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Proof of relativity

  1. Apr 29, 2009 #1
    Can you describe some proof of either form of relativity, whether it be theoretical or observational, that can be understood by someone without a degree in physics or maths.

    I am sure there is some, but so far all I have found is that when they put an atomic clock on the space shuttle, it ran slightly slower relative to an atomic clock on earth.

    Can I also point out that I can understand the general (and some of the slightly more complicated) points about reativity- I'm only interested in the proof of it.
     
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  3. Apr 29, 2009 #2

    tiny-tim

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  4. Apr 29, 2009 #3

    HallsofIvy

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  5. Apr 29, 2009 #4

    Dale

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  6. Apr 29, 2009 #5
    The other famous experiment testing Einsteins general relativity is the prediction (and then observed) extra bending of light, the experiment carried out by Eddington. I believe there is also now experimental evidence of 'frame dragging' that is predicted by relativity, observations of unstable particles created by cosmic rays in the upper atmosphere that shouldn't exist long enough to reach the surface but do thanks to time-dilation effects and probably lots more (I expect particle accelerators have a lot of evidence showing particles increasing in mass as they accelerate them closer to the speed of light for example).

    Of course, none of this is actual 'proof' of relativity, it's merely observational evidence that backs up the theory. The proof is entirely mathematical and is only 'true' if it's axioms are correct :)
     
  7. Sep 4, 2009 #6
    Other interesting applications/observations are GPS satellite systems and the Gravity Probe B satellite results. In GPS system clocks,for example, must be adjusted because ones in space run faster than one's on earth. If you search for Gravity Probe B you can read about some work completed and other work underway regarding confirmation of spacetime curvature...The Stanford University site had a lot of information including at 26 minute video.
     
  8. Sep 4, 2009 #7

    atyy

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  9. Sep 4, 2009 #8

    alxm

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    Kind of an old thread, but I can't help but enter my favorite confirmation of Special Relativity (also in the FAQ, but at another location): The http://www.edu-observatory.org/physics-faq/Relativity/SR/gold_color.html" [Broken].

    The band-gap which is in the UV in silver (and 'non-relativistic gold') is downshifted into the blue, giving the yellow color. Giving blue absorption and a yellow color. So if SR was false, the band would be in the UV and gold would be silver-colored like most metals.

    It's the predictive power of Science it its best, since nobody had the faintest idea that relativity had anything to do with that when the theory was devised.
     
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  10. Sep 4, 2009 #9

    tiny-tim

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    Hi alxm! :smile:
    Is that right? According to Pekka Pykkö in http://books.google.com/books?id=jr...lient=safari#v=onepage&q=relativistic&f=true" at p.355 …
    Isn't it simply based on the increased mass of an "orbiting" electron, causing contraction of the inner shells (from F = ma, not from Lorentz-Fitzgerald contraction!), which would have been obvious from the start?
     
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  11. Sep 5, 2009 #10
    When physicists at Brookhaven National Laboratory put muons (mass 105.658 Mev/c2) in a magnetic storage ring at total energy 29.3 times the rest mass, the decay lifetime, usually 2.2 microseconds, stretched by a factor of 29.3 to about 64 microseconds. See
    http://www.g-2.bnl.gov/publications/prl2001.pdf
     
  12. Sep 6, 2009 #11
    Actually, it might be possible to prove special relativity from electromagnetics, right? This is something I've been trying to find out about. I mean, it wouldn't prove that the same rules apply to other forces, but you could at least show that E=mc^2 and time dilates and space contracts for the purposes of electromagnetic phenomena, am I right?

    Well, I don't want to derail the thread, but does anyone know if that's a yes or no, at least?

    EDIT: when I say "prove", I mean "prove from Maxwell's equations".
     
  13. Sep 11, 2009 #12

    alxm

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    It was obvious almost from the start that it would have an effect, once the general idea of atoms (not really known in 1905) got cleared up, and people began to understand at least the approximate magnitudes of electronic momentum in heavy atoms. (= Sommerfeld, 1916)

    But it was not obvious that the specific effect of gold's yellow color was due to relativity. It wasn't until the 50's-60's really, until quantum-chemical methods got accurate enough to say with any certainty that non-relativistic methods wouldn't be able to account for the difference, effect, and it wasn't until the 70's (I believe) that they were actually able to do the full relativistic calculation of the bands and finally prove this was the case. You really have to solve the Dirac equation for the thing.

    It'd have been impossible to know early on - it could well have been related to the lanthanide contraction for instance, which is mostly due to the nature/geometry of 4f orbitals, but partially due to relativity as well.
     
  14. Sep 11, 2009 #13
    is this the same as time dilation? because as i recall, if you travel at the speed of light for a certain amount of time, much more time will have passed on earth than in your spaceship more or less
     
  15. Sep 12, 2009 #14

    tiny-tim

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    (near the speed of light, yes)

    It's all connected … time dilation implies length contraction, and vice versa.
     
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