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Is gravity really that weak?

  1. Oct 16, 2015 #1
    All physicists I've heard discussing gravity to the public always mentions that it's a very weak force compared to the other forces and that noone knows why. One possible reason could be that the gravitational force is propagating in other dimensions.
    As far as I know gravity works in a completely different way compared to the other forces. The other forces use carrier particles but gravity works by curving the fabric of space and time.
    Aren't we comparing apples and oranges when we are comparing the strength of gravity to the strength of the other fundamental forces?
  2. jcsd
  3. Oct 16, 2015 #2


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    I feel that it is not really for me to answer this question (others here have the actual knowledge to do so), but I would think that one can still compare the relative strength of different fundamental forces, even though these forces may be mediated by different mechanisms. In other words, I don't think this is a matter of comparing apples and oranges. Is this correct?
  4. Oct 16, 2015 #3


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    See e.g.

    I'd say the comparison is not that bad. In theory we can measure e.g. the electric force between a proton and a neutron in a Hydrogen-atom, and do the same for gravity. Doing the math with it gives a huge difference. between the two. Of course, in GR gravity is merely an 'inertial force', but that shouldn't be a problem. Somebody on a spinning disc can also compare the centrifugal force he/she is measuring with the gravitational force she is undergoing, do the corresponding math and compare the two.
  5. Oct 16, 2015 #4
    Of course you can compare the forces but since the mechanisms behind the forces are completely different I don’t understand why we need an answer to why the gravitational force is so much weaker than the other fundamental forces. If the gravitational force were in the same order of magnitude as the electromagnetic force in strength I think it would be an incredible coincidence.
    If there was a graviton, carrying the force the same way as photons do with the electromagnetic force, I would have understood the concept of finding out what causes the forces to be so different in strength but since those forces work in a completely different way I don’t understand why we need an additional explanation, like gravity propagating in extra dimensions.
  6. Oct 16, 2015 #5

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    First, the forces are what they are, irrespective of our models. An airplane is faster than a snail, even though they are totally different objects moving in totally different ways. Yes, gravity can break your leg, but it takes a whole planet to do it. That's pretty weak.

    Second, the fact that our best mathematical models of gravity don't look anything like our best mathematical models of other forces may or may not be telling us there are fundamentally different. The map is not the territory.
  7. Oct 16, 2015 #6


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    That's the most vivid demonstration of the weakness of gravity I ever seen. :smile:
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