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Gravity Confuses Me

  1. Jan 3, 2007 #1
    There's no such thing as gravity, the Earth sucks!

    For some reason I've been seeing a rather large number of media presentations (TV, magazines) regarding The Theory of Everything. This usually launches into a discussion about how physicists have not been able to reconcile gravity with quantum theory.

    Invariably, they bring up Einstein's theory of gravity; i.e. that a mass warps space and draws in other masses due to the curve of space. This idea of gravity has made me wonder if gravity is truly a force or is just the manifestation of how space is warped. For Newton, gravity was an attractive force between two bodies. For Einstein it was because things tend to move towards warps in space.

    Gravity is one of the four fundamental forces in the universe. However, we have not been able to manipulate it or even directly observe it like we have with the other three forces; electro-magnetism, strong and weak. We can even manipulate those forces with a great degree of success, sometimes in spectacular ways. But we can't do this with gravity. I'm no physicist, but I've never even heard of any ideas of how this can be done. We're still trying to find ways to detect some of the predicted properties of gravity, most notably gravity waves.

    So is it a force or merely the byproduct of how space is shaped?

    Please be gentle with me.
  2. jcsd
  3. Jan 3, 2007 #2
    Well I think nobody knows if it is a force or a curvature effect.
    How would we even begin to determine that experimentally! :smile:

    The general theory of relativity uses a geometric explanation for gravity and currently it is by far the best and most accurate theory we have concerning gravity.

    It might be that in the future someone will develop a competing theory using gravitational force carriers called gravitons which work in the realm of QFT.
    But so far no quantum gravity theory is even close to the predictive value of general relativity theory.
  4. Jan 3, 2007 #3
    So you're saying that everybody else is as confused as me?
  5. Jan 3, 2007 #4


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    Pretty much, yes. Gravity is certainly the least well understood of the four forces.

    - Warren
  6. Jan 3, 2007 #5
    But we do know that space seems to behave as if it's curved according to the general theory of relativity. That's why the curved-space view gets airtime, even though the gtr isn't completely in agreement with all our other physics.

    Even if space always behaved exactly as if it were curved, we still couldn't tell whether it's actually curved or whether there exists some other condition that has the same effect.
    Last edited: Jan 3, 2007
  7. Jan 4, 2007 #6
    Gravity is one of those things that were are able to predict its movements/results almost on the dot but many people have conflicting theories. In reality we may never know the true thing that causes gravity. You could say that gravity is caused by mass, but why is it caused by mass??:confused: You could say that mass itself curves space but why does mass curve space?:confused:
  8. Jan 4, 2007 #7
    I thought mass is caused by the Higgs field?
    Then the Higgs fields warp spacetime.
    Or the Higgs fields is merely a curvature of spacetime?
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