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Does strong force = gravity at very small distances?

  1. Jan 6, 2010 #1
    this is probably either a really dumb question, or just a dumb question. But with my remedial knowledge of these fundamental forces it seems a logical question to ask.

    Gravity is deemed the weakest force, but maybe that's just a range related perspective. It gets stronger with decreasing distance so how strong would gravity between two particles be at the distance that two protons are from each other inside the nucleus of an atom? Maybe as strong as what is deemed the strongest force?
  2. jcsd
  3. Jan 6, 2010 #2


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    Both gravity and electromagnetic forces are inverse square forces. This means that if EM repulsion is stronger than gravity at one distance it will so be at all distances. But the strong force specifically is what holds the nucleus of an atom together in spite of the EM repulsion between the nuclear protons. Thus in a standard setting, NO the strong nuclear force can't be conventional gravity.

    Now you might wonder then about black holes which goes beyond standard inverse-square potential. But for the particles inside a nucleus to be bound inside a little black-hole then two things would happen...a.) slamming them together you would not be able to break off parts as we see in colliders, and b.) the size would be too small for the scattering cross sections seen in experiments.

    Also we have a good theory of the strong force in quantum chromodynamics. It explains the binding of nuclei, as well as the variety of particles we get when we do nuclear collisions at high energy (mesons and baryons and such). Might I suggest you read t'Hooft's book http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=0521578833"

    It is a good exposition of the history of our understanding of subatomic phenomena written for the curious layman.

    Now this is not to say that some future theory might not unify the forces so we can say the strong force is "another type of gravity" or something similar. But it could also be otherwise... we won't know until we know.

    EDIT: PS. By the way, I asked the very same question of my physics teacher in highschool. He just laid a definitive No! No way! without explanation. Though I believed him I didn't figure out why not for some years.
    Last edited by a moderator: Apr 24, 2017
  4. Jan 6, 2010 #3
    thanks for the reply. That was a good explanation that I could understand. And thanks for the suggested reading, I'll check it out.
  5. Jan 6, 2010 #4
    The strong force also increases its power with distance within the hadron, so it is quite different from gravity in that perspective.
  6. Jan 6, 2010 #5
    Just to add, the strong force is restricted to the atomic scale. There is a certain distance at which the strong force isn't present. That's why it wasn't discovered until physisists didn't discover this force until they started seaching the atom.
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