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Gravity and the expanding universe

  1. Sep 13, 2012 #1
    OK, a couple of things.

    1. I know there are a few theories of "why" gravity exists with gravitons and entropy, etc. But know one really knows.

    Does anyone have any good websites where all theories are discussed in one section? I am having to go all over the place to find information.

    And 2. This is just me wondering, If all object produce gravity, and the larger they are the more gravity they produce, then why is the universe expanding rather than shrinking? Doesnt it make more sense that all solid obejcts atract each other. I understan that orbits cause objects to travel past each other, but eventually wont everything just collapse back on itself?

    Any insight appreciated it.

  2. jcsd
  3. Sep 13, 2012 #2


    Staff: Mentor

    your best bet is to explore wikipedia to read about the various theories.

    Just keep in mind science can't answer why. It can provide a theory that models the phenomenon remarkably well from which we imagine we understand how it works but not the why of it.

    Theories of Gravitation:
    - newtonian
    - einstein's general relativity
    - loop quantum gravity

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