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Gravity, cause or effect of time dilation?

  1. Feb 28, 2008 #1
    With GR saying that gravity is just curved spacetime, wouldn't that make gravity the effect of the time dilation properties of matter?
     
  2. jcsd
  3. Feb 28, 2008 #2
    cause.

    Regards,

    Bill
     
  4. Feb 28, 2008 #3

    Mentz114

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    What time dilation properties ? It seems you are just renaming gravity ( caused by energy/matter) as 'time dilation property.
     
  5. Mar 1, 2008 #4
    Am I mistaken that all matter is embedded in gravity? I thought that one of the ways that GR was confirmed was the gravitational red shift of a photon, and like the red shift from a distance source we associate it with expansion. The only expansion I associate with matter is in the time dimension as all matter stays the same in the other three dimensions relative to me, which brought me to the question posted above.

    This is a wonderful site and I enjoy reading it, I do try to keep my questions to one at a time and not too many per month, and yes I may be calling things by the wrong names but your answers always help me get things right; at least in my own mind. Thanks everyone.
     
  6. Mar 2, 2008 #5

    Mentz114

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    There are two sources of red-shift. In a famous experiment, Pound and Rebka showed a frequency shift between two points on earth, which is caused by the difference in gravitational potential.

    en.wikipedia.org/wiki/Pound-Rebka_experiment

    The other red-shift is seen in light coming from distant sources, and is thought to be due to cosmic expansion, as predicted by the Robertson-Walker cosmological metric. There is no way to separate these effects in any observation.
     
  7. Mar 3, 2008 #6

    Except for the position of the observer, who faces either in or out and will always be able to tell the difference in sources. Matter the embedded part of us with which we measure time appears to be expanding in time, inward, even though we don't see it except as a red shift of a photon. This is the time dilation property of matter. I am asking could gravity be how we measure the time dilation properties of matter, after all time dilation could be one half of the warping to space-time.
     
  8. Mar 3, 2008 #7

    Mentz114

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    Gravity and time dilation happen together, but that does not mean that one is causing the other. They may both be the effect of some other cause - like the presence of a large mass.
     
  9. Mar 3, 2008 #8
    Yeah - like the presence of a large mass implies gravity, and gravity implies time dilation. :rolleyes:

    Regards,

    Bill
     
  10. Mar 3, 2008 #9
    I'm sorry, this sounds like a lot of jargon that doesn't amount to anything.

    You can get time dilation in one of two ways: going really fast relative to your "fixed" object, or gravity. Both of which end up contracting space-time.

    The reason we think gravity makes time-dilation and not the other way around, is because we can manipulate gravity (adding or subtracting mass/energy) but we can't "make" time-dilation and then see mass pop up somewhere. It wouldn't make sense.
     
  11. Mar 6, 2008 #10
    We can't "make" gravity nor can we make time dilate, but both of these properties are assoiated with matter. I was just wondering if one was a cause and one an effect or if they could be the same thing.
     
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