I'm really stuck on the following idea. For gravity to in any way be 'unified' with the electroweak interaction wouldn't it need to include a model whereby the electron somehow tunnels to within the first electron shell of atoms from a mass approaching another mass and transmit a $W+$ or $W-$ particle (don't know which) between the electron and the nucleus? I'm thinking that if this isn't the case then it's best to just can the whole 'quantum gravity' stuff altogether and just stick with spacetime, which is like a 'fabric' and just say that there's no such thing as a 'graviton' at all. I'm sick of all this stuff.


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  • $\begingroup$ Take a break. come back if you want to. $\endgroup$ – JMLCarter Jul 15 '18 at 22:24
  • $\begingroup$ Sounds god. Please go ahead and can the whole quantum gravity stuff altogether. $\endgroup$ – safesphere Jul 16 '18 at 1:06
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    $\begingroup$ I don't see why you're making this leap from "tunneling electrons" and the electroweak field to gravity - there's no connection. But in any case general relativity (a non-quantum theory) works perfectly well for the purpose it's intended and quantum field theories do a perfectly good job of explaining the standard model of particle physics without general relativity. A quantum gravity theory is really the exploration of the extreme edge of theory and beyond our current experimental capabilities. $\endgroup$ – StephenG Jul 16 '18 at 3:52
  • $\begingroup$ @StephenG 'there's no connection' - ok, then we clearly need to stop QG research altogether. For what purpose was GR intended? To explain gravity's effects within the solar system. "A quantum gravity theory is really the exploration of the extreme edge of theory and beyond our current experimental capabilities." If that's the case, they're not even doing science. $\endgroup$ – Sam Cottle Jul 16 '18 at 14:58

I'm just guessing, but your logic seems to be that if gravity is unified with electroweak force, then a graviton has to be like a W boson and that's only a short-range force, so the two electrons would have to get close to exchange a graviton.

But a W boson is a short-range particle only because it is massive, and it is massive only because the Higgs field (1) has an electroweak charge (2) has a nonzero vev in its ground state.

By cotrast, the photon is the electroweak boson that doesn't interact with the Higgs field, and it is massless and long-range.

Also, quantum gravity does not conceptually require that gravity and electroweak forces are unified. Naively, gravitons are just a different class of particle. It's only in supergravity and string theory that they are unified with gauge bosons in various ways.

  • $\begingroup$ Ok, thanks for that. I was coming at this with supergravity/string theories in mind; I've always been told that they are a major, if not the major, approach to 'quantum gravity'. I guess I was also unsure as to what, exactly, the difference between unification theories and quantum gravity would amount to; in my understanding, it's only gravity and EM that appear to be long-range forces whereas the weak force just acts on the quantum scale. $\endgroup$ – Sam Cottle Jul 16 '18 at 15:01

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