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What is gravity

  1. Jul 15, 2009 #1
    I understand the forces of gravity, how to model it ect. I even vaguely understand relativistic gravity, but these are just descriptions of how gravity works. What is gravity? Why does mass attract other mass (or warp space time)? Is there an answer for this?
     
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  3. Jul 15, 2009 #2

    Jonathan Scott

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    Not yet, as far as I know.
     
  4. Jul 15, 2009 #3
    Some physics believe there is a particle, the graviton, which is the carrier of the gravity force, just like the photon is to the electromagnetic force. But proving that such a particle exist seems to be very complex (I don't have enough knowledge to even try explaining it). Here is when such theories as string or M theories come trying to find the answer for gravity.
     
  5. Jul 16, 2009 #4

    Chronos

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    That is still a question without a clear answer.
     
  6. Jul 16, 2009 #5
    Gravity is one of four fundamental force in this universe besides strong, weak and electromagnet. If you ask, how those forces work, then each force do has a force carrier particle. For electromagnet is photon, strong is gluon, weak is vector bosons and gravity is graviton.
     
  7. Jul 16, 2009 #6
    The problem is that General Relativity does not use this 'force carrier particle' concept. And in fact, in some ways is inconsistent with it. The plus side to this is that the supposed graviton has never been detected -- and may not exist. So GR may be right in not doing so.

    However, it is still possible that a photon might be involved as the 'force carrier' for gravitation as well as for electromagnetism. Never ending theories -- what science is all about.
     
  8. Jul 17, 2009 #7

    Chronos

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    Einstein thought gravity was a geometrical effect, the curvature of spacetime in the presence of matter. A boson is not necessarily required. That was mostly imposed by string theory.
     
  9. Jul 17, 2009 #8
    Yes, he did. And at that time quantum physics was in the future. Particle physics has made gigantic strides since his time.

    I do think that GR can and does give good and valid results in most every case -- EXCEPT when applied to cosmology as it has been. It still may be able to be modified for that situation too.
     
  10. Jul 18, 2009 #9

    Chronos

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    No doubt, but a better theory has not yet been proposed.
     
  11. Jul 18, 2009 #10
    There will always be a better theory.
     
  12. Jul 18, 2009 #11
    when you say you understand gravity and its forces ,you would also
    understand that it is the very same force that causes bodies having mass
    to get attracted.
    and as to why this happens,that is the nature of this force,and as to why it has
    this nature,it is because the apple fell 'down' and not up.
     
  13. Jul 18, 2009 #12
    Well, believe it or not there are some people that have a theory of gravity that says just that!
    (Definitely NOT mainstream!)
     
  14. Jul 18, 2009 #13
    i dont undersatnd even if gravity is a particle or not..how does it matter.. has nay one seeen any particles like the particles of electromagnetic force ..nope!!
    then in fact we just assume things then waht so much mistry around gravity..pata nahin !
     
  15. Jul 19, 2009 #14

    Chronos

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    There is a perception gravity should behave similarly to Maxwellian [EM] forces, which are mediated by bosons. It is less clear if gravitational fields are similarly well behaved.
     
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