Gr Questions.

Its not the amount of mass that is singular in classical general relativity for a black hole, it is the "density" of the mass that is singular. Who knows, maybe the correct quantum gravity theory will not have an infinite density for it. My point is that both classical electromagnetism without general relativity, and general relativity treat charges as point masses. Both treat them as having finite mass, but infinite density. Both describe the density as a singularity. The only difference is that for black holes there are event horizons around the singularity. I don't think the divergent terms in the Reimann tensor corresponding to the mass density at its location can be transformed into something finite without giving rise to other divergent terms.

This post has been edited by waitedavid137 on Sep 20 2011, 05:32 PM

I'm aware of the point particle treatment but I never thought about treating the black hole that way. Treating a particle as a 'string' with finite extent eliminates the infinite density. String theory has it's own problem with finding a preferred vacuum from a 'huge' population of candidates. I certainly don't think GR has any problems since all this stuff is outside the GR domain of applicability. Just want to make that clear so that boundaries don't get theoretically washed over. Thank you for your comments. Have you thought about 'choosing the preferred vacuum for string theory'? The two camps of thought. One requiring empirical confirmation and the other utilizing anthropic reasoning. A bit off topic.

I really don't put too much stock in strings yet. It seems presumptuous to me to be trying to determine which string theory, or which guage for strings really, is correct when there's no real physical evidence that strings are the correct approach to unification at all yet.

I wouldn't say presumptous since the domain of applicability is, for the most part, untestable. I take from your comment that you might think the research on quantum gravity is doomed to failure because the domain is essentially untestable?

No, I'm sure we'll come to be able to test it someday. This is still a world of savages. There is a lot of room for growth for our descendants yet.

I like to hear that. Thanks for all the informative comments in this thread.

Very nice explanation. Pleased to read you.