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Do the Einstein field equations successfully predict/describe physical processes other than gravitational ones?

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  • $\begingroup$ From the very link you provide, first sentence: "The Einstein field equations (EFE; also known as "Einstein's equations") are the set of 10 equations in Albert Einstein's general theory of relativity that describes the fundamental interaction of gravitation". What is your question? $\endgroup$ – Stéphane Rollandin Jun 24 '16 at 18:19
  • $\begingroup$ Sorry if it was confusing Stephane. The question is, do the EFE predict and/or describe any physical processes other than gravity itself? For example, do they provide a basis for electromagnetic radiation, that sort of a thing. $\endgroup$ – yimiller Jun 24 '16 at 23:18
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    $\begingroup$ Are you asking if EFEs contain Maxwell's equations? $\endgroup$ – Qmechanic Jun 25 '16 at 15:41
  • $\begingroup$ I didn't mean to ask specifically about Maxwell's equations. I am just seeking a broader understanding of what the EFE predict and/or describe, other than what I find in standard astronomy/cosmology references. $\endgroup$ – yimiller Jun 25 '16 at 18:48
  • $\begingroup$ See my comment below, placed in the wrong place and can't move it. The other thing is that you can insert electromagnetic fields in the EFE and it seems to work, so interactions of EM and gravity or EM in strong gravita Iona's fileds are covered, but not quantum effects. You can also insert other quantum field in EFE gravity. $\endgroup$ – Bob Bee Jun 25 '16 at 21:19
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General relativity is a theory of gravity; as such, it makes predictions about gravity. However, general relativity does make predictions about time and physical entities such as black holes. Some of the predictions general relativity did make:

  • Gravitational waves exist (proved by LIGO last year)
  • Black holes exist
  • Light bends (proved in 1919 by an expedition led by Sir Arthur Eddington)
  • Mercury's orbit was predicted (Newton's predictions weren't perfect)
  • Time is variable from person to person (the only constant is the speed of light)
  • Other predictions are included at this website.

Hope this helps!

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Certain condensed matter systems show emergent behavior that is similar to general relativity: see this for example. Also, in fluid mechanics, sound waves can become trapped behind an "event horizon" called an acoustic black hole. Finally, the Einstein field equations are essentially the only possible classical equations of motion for a massless spin-two particle, so any massless spin-two particle would "look like" a graviton even if it didn't actually mediate the gravitational force, as discussed in the question Would a spin-2 particle necessarily have to be a graviton?

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  • $\begingroup$ If spin 2 it has to interact with matter the same way as gravity, and have the geometric interpretation. Sure, it could have a different coupling constant than G, but unless much lower we would have observed it. From what I understand the only other possibility is that gravity as we know it does not interact with certain kinds of particles (antiparticles, ssuperparticles, etc), and maybe some other flavor of graviton might. Not sure the limits on that but no evidence of any of that. $\endgroup$ – Bob Bee Jun 25 '16 at 21:16

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