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How can gravitons be emitted from a mass to cause an attractive force to another mass? The same question could be asked of attractive e-m forces as well. Don't these violate the conservation of momentum (not of the masses themselves, but of the particles mediating the forces)?

Qmechanic
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Jiminion
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    Possible duplicates: http://physics.stackexchange.com/q/171564/2451 and links therein. – Qmechanic Jan 04 '16 at 19:13
  • The notion of a field is introduced to salvage the conservation of energy and momentum. The field acts as a reservoirs of both the quantities, which are mediated by the quanta of the field (on a quantum level). – Phoenix87 Jan 04 '16 at 19:13
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    Please see my answer here http://physics.stackexchange.com/q/227218/ to understand that the exchanged "particles" are mathematical representations in Feynman diagrams, not real particles with a fixed mass. – anna v Jan 04 '16 at 19:13
  • The reason why the mental model breaks down is because it is wrong to begin with. Force mediating bosons don't "move", they are measurement values on a field. – CuriousOne Jan 04 '16 at 19:14
  • Thank you. My initial reaction to the "because of fields" answer is that is substitutes the vague particle with the vague field. Especially since the gravity field is allegedly the deformation of space and the E-M field is something else, but also conveniently acts as an 1/R2 force. – Jiminion Jan 04 '16 at 19:31
  • There is nothing "vague" about either particles (which do not even belong in here) or fields. You might be uncomfortable with the necessary relativity of science in general. In physics, in particular, we can only express one set of natural observations trough their effects in terms of other sets of natural observations. This is perfectly well defined but, admittedly, unsatisfactory if you are looking for some "absolute" set of truths... that's just not how science operates. The experimentalist is a little more comfortable with it, since he/she doesn't have to chase philosophical wild geese. – CuriousOne Jan 04 '16 at 19:45
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    Maybe the graviton is the wild goose – Bill Alsept Jan 04 '16 at 20:46
  • OK, based on Phoenix87, does this mean that the fields can embody (effectively) negative energies of say, virtual photons? (I'll stick with E-M as gravitons are a bit suspect.) Like CO, I don't see fields as a definition vs. an observation. But just observing something doesn't mean we understand it. – Jiminion Jan 04 '16 at 21:02

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