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Photon/gravity question

  1. Sep 29, 2003 #1
    Ok, here goes nothing...
    Gravity bends photon trajectory, correct? This can be varrified by experiments pertaining to gravatational bending. I THINK also termed 'Einstein's Cross'.
    Now, is there a possibility that there is a reciprocal effect? That gravity could be created, or related to the curved trajectory of a photon?

    Paden Roder
     
  2. jcsd
  3. Sep 29, 2003 #2

    Nereid

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    A.k.a. gravitational deflection (of light). Lots and lots of observations and verified to a high degree of accuracy. First test was by Eddington, in 1919, during a solar eclipse. More here:
    http://www.newtonphysics.on.ca/ECLIPSE/Eclipse.html

    Einstein Cross refers to a quasar which is on the line of sight through a much closer galaxy. E.g.:
    http://antwrp.gsfc.nasa.gov/apod/ap961215.html

    The closer galaxy acts as a special lens, magnifying and distorting the image of the background quasar. Several such examples have now been found. The image properties allow further tests of GR, and also many interesting and important estimates, of things like dark matter.

    The more general case is called 'gravitational lensing'.
     
  4. Sep 29, 2003 #3

    chroot

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    And yes, photons carry energy. Energy curves space exactly as well as does mass. Of course, you'd have to have quite a bit of light energy around to make a gravitation field detectable in a laboratory...

    - Warren
     
  5. Sep 29, 2003 #4

    Nereid

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    IIRC, the gravitational attraction between quite small masses (<1 gram) and over short distances (<1 mm) has now been measured.

    Photons with energies > 10 TeV have been detected, albeit indirectly.

    When (200n, 20nm?, 2nmp??) do you expect a successful observation of the gravitational field produced by a photon will be made?
     
  6. Sep 29, 2003 #5

    chroot

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    Well, the technology that would be needed to generate those photons and the technology to measure their gravitation are both many orders of magnitude more sophisticated that current cutting edge technology.

    Without specifically knowing the rate of advancement of these fields, I'd venture it'll be at least 100 years away.

    - Warren
     
  7. Sep 29, 2003 #6

    Claude Bile

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    Can you quote a reference? I was unaware that measurements of gravitational fields had reached this precision.

    Claude.
     
  8. Sep 30, 2003 #7

    Nereid

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  9. Sep 30, 2003 #8

    Claude Bile

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    Amazing....
     
  10. Oct 1, 2003 #9

    Nereid

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    Yes.

    I asked: When [to] expect a successful observation of the gravitational field produced by a photon will be made?
    chroot answered:
    At least two astronomers think it will be possible before 2010, by observing the frequency-dependent propagation of high-energy photons from GRBs (strictly speaking, they feel that GLAST observations may be able to test quantum gravity, but the data may also show the effect PRodQuanta asks about, and perhaps even the VSL of paultrr!). The link:
    http://glast.gsfc.nasa.gov/science/grbst/pubs/GLAST_GRBs_QG.pdf

    A big thanks to Jeebus for his pointer to this
     
  11. Oct 1, 2003 #10

    chroot

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    Re: Re: photon/gravity question

    You know, the sad part is that I did not consider astrophysical systems -- I was thinking about measuring the effect in a laboratory!

    Nereid, the proposal does sound promising!

    - Warren
     
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