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Question about gravity on the large scale.

  1. Jan 11, 2013 #1
    I was thinking about olbers paradox and how I could apply it to gravity.
    We assume that their are an infinite amount of planets and that they are all about
    the same mass or we will just pick a minimum mass. And we assume they are evenly distributed. So the gravitational field falls off as 1/r^2 but the amount of planets grows
    as r^2. So If there were an infinite amount of planets or stars or whatever, we would experience an infinite pull, but this would be in all directions so it might cancel.
    i guess this is similar to gauss's law. But how would we know where the center is or how would we balance these infinities?
     
  2. jcsd
  3. Jan 11, 2013 #2

    mfb

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    We are all in the center of our observable universe with a finite age - and as space looks nearly the same in all directions (if you are at rest with respect to the CMB), you don't get a significant attraction. There are some attracting things if you have a closer look.
     
  4. Jan 11, 2013 #3
    How would you know you at rest compared to CMB
    Would you tell by measuring the frequency.
     
  5. Jan 11, 2013 #4

    mfb

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    You measure the temperature (which is related to the total intensity) and look for a dipole moment: If the CMB is hotter in direction X and colder at the opposite side, you are moving towards X (relative to the CMB).
     
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