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seen Jun 22 '12 at 3:14

Undergraduate student in Mathematics and Physics.


Jun
26
comment Asymptotic Invariants in General Relativity
On an unrelated topic, I was wondering if you have any thoughts on why ADM energy and momentum are the only possible $1/r$ invariants, or maybe you know a reference that touches on these matters? Thanks again.
Jun
26
comment Asymptotic Invariants in General Relativity
Hi Willie, thank you for your comments and for the reference. I should have thought that a general definition of angular momentum requires stronger fall-off conditions than the ones presented in the definition of asymptotic flatness, since otherwise it would be defined together with ADM energy and momentum in most references. But I certainly didn't expect for the problem to be so much trickier; for instance, in the paper you linked it is argued that one cannot choose arbitrary coordinates for then covariance of angular momentum cannot be guaranteed.
Jun
25
awarded  Student
Jun
25
asked Asymptotic Invariants in General Relativity
Jun
24
comment Can black holes form in a finite amount of time?
@Anixx Yes. See the Schoen-Yau paper on formation of apparent horizons (the relevant result is theorem 2).
Feb
12
awarded  Editor
Feb
12
revised Can black holes form in a finite amount of time?
added 1 characters in body
Feb
12
awarded  Supporter
Feb
12
answered Can black holes form in a finite amount of time?
Nov
20
comment Event Horizon violability?
By topological sphere I mean a surface which is homeomorphic to a sphere. It does not need to be precisely spherical, all that is needed is that the Euler characteristic be 2. Of course, during the merging of the black holes the event horizon might deform, but at any time it is homeomorphic to a sphere, i.e., you can't create "holes" in it.
Nov
20
awarded  Teacher
Nov
20
answered Event Horizon violability?