ArmonSore wrote:Well, inertia is certainly a resistance to accelerations. And somehow your amount of inertia also causes bends in spacetime. So there should be some connection, though I'm not aware what the link between the two is.
Yeah, yeah. We've heard it all before. This is more than a coincidence.Not quite: gravitational mass (the quantity proportional to how much you "bend" space-time) and inertial mass (the quantity proportional to your resistance to acceleration) are distinct concepts. It just so happens that they appear to have the same value for all kinds of matter we know about.
SpitValve wrote:I thought the point of GR was that it's no longer a coincidence that gravitational mass is equal to inertial mass because gravity isn't a force anymore?
In Newtonian you have a=F/m=GMm/r^2/m=GM/r^2 which is indpt of m, and seems awfully convenient, but in GR it's just a natural consequence of the metric.
ArmonSore wrote:I agree with Vaniver, it's too nice to be by chance.
And I'd like to know more about what SpitValve is talking about.
ArmonSore wrote:But I'm still not understanding why your mass causes a change in spacetime, while also defining how you'd react to regular old forces. Why does this single quantity we call inertia do both things?
ArmonSore wrote:Is the mass that causes gravity in GR the rest mass, or the apparent mass?
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