View Single Post
rbj
rbj is offline
#68
Aug30-08, 11:32 PM
P: 2,265
Quote Quote by MeJennifer View Post
I think you are mistaken. In fact if you look how Einstein derived GR you will see he simply included the Newtonian limit as a given. Technically GR is simply Newtonian gravity plus relativistic effects. GR does not explain anything, it is simply a more accurate theory.

If you think I am mistaken, please demonstrate how it explains the inverse square law. Or an even simpler question: How does GR get to the Newtonian limit.
does John Baez do that here?

or maybe Sean Carroll does that here or here?

i think they can derive the inverse-square relationship (or maybe it's a 1/r relationship for potential energy) for the flat space-time limit. the constant of proportionality in the Einstein equation ([itex]8 \pi G[/itex]) does come about to be compatible with Newtonian gravitation.

i can't actually do the math myself (i am ashamed to confess i never figured out tensors), but it appears that this is what they do.