MadSci Network: Physics |
Hello, Kirk. Gravitons supposedly carry gravitational attraction. They do not cause it. I say "supposedly" because gravitons might not exist. In the universe we know of four fundamental forces; electro-magnetism (electricity and magnetism), the strong nuclear force (which holds atoms together), the weak nuclear force (which causes radioactive decay), and gravity (which keeps me from slam dunking a basketball, no matter how hard I try). Each of these forces is carried accross distances by sub-atomic particles called bosons. It's a little misleading to call bosons "particles" because they have no mass and behave somewhat like waves. The electro-magnetic force is carried by photons. The strong nuclear force is carried by gluons. The weak force is carried by weak bosons, and gravity is carried by gravitons. Or so we thought. Earlier in this decade, it was shown in a brilliant piece of detective work by Sheldon Glashow, Abdus Salam, and Steven Weinberg that the electro-magnetic force and the weak nuclear force are actually one and the same. Radio-active decay is carried by photons after all, and weak bosons don't exist. It's very possible that the graviton doesn't exist, either. It's predicted mathematically, but so were weak bosons. Once it was found that the weak nuclear force was just a manifestation of electro-magnetism, it was realized that the basis for predicting weak bosons was faulty. If gravity is ever unified with the other forces, then gravitons won't be needed anymore, and the theory will be discarded. It's interesting to note that of the sub-atomic particles we've observed so far (over 400!), we've yet to see the graviton. But let's assume that gravitons do exist, and are just what the standard model predicts they are - massless bosons with two units of spin charge. Gravitons carry gravitational attraction between two massive bodies, in the same way that photons carry magnetism, or gluons hold electrons in orbit around nuclei. How exactly that's done hasn't been explained. But I'll give you my opinion about it. Everywhere, even in a complete vacuum, there exists a sub-atomic network of lines. They connect everything to everything else. Every particle is linked to every other particle in the universe by these lines. They can't be seen or detected, because they're not comprised of matter. But to help us visualize this, we will imagine that these lines are actually ropes, tying everything together. The difference between our imaginary ropes and real ropes cowboys use is that our ropes can pass through other ropes, and no damage is done. The gravitational attraction between two bodies can be explained by waves in the rope. Remember, the graviton exhibits wave-like behavior as well as particle-like behavior. Since our rope can't stretch or break, waves shrink the distance between the two bodies, like this - 0------------------------0 _ _ _ 0\_/ \_/ \_/ \0 If this is the behavior of gravitons, we never can find them in particle accelerators. They're not particles being emmitted from massive bodies, they're waves traveling along the network of lines that connects massive bodies. Their ability to carry the force of gravity is due to their wave-like behavior, not their particle-like behavior. It makes more sense that way. Unfortunately, quantum happenings don't have to make sense. I may have it all wrong. I'll leave you with two quotes from two of the fathers of quantum physics. "I think I can safely say that nobody understands quantum mechanics" - Richard Feynman "If you're not confused by quantum mechanics, you really don't understand it" - Niels Bohr I hope I was of some help, Layne Johnson
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