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TimeRip496
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What happens if you apply EFE to a small particle like electron? Is it where efe breaks down and have to be replaced with quantum gravity? My apologies for such a dumb qns as I just started.
TimeRip496 said:What happens if you apply EFE to a small particle like electron? Is it where efe breaks down and have to be replaced with quantum gravity? My apologies for such a dumb qns as I just started.
stevendaryl said:GR doesn't say that nothing can violate this constraint, but something that violates it will not have an event horizon. It will be a "naked singularity" I guess.
Do you mind telling me more about that event horizon? As far as I know, it is a border of a black hole at which light cannot escape upon crossing it. But how do you obtain that equation?stevendaryl said:If you try to analyze a single electron using General Relativity, there are a few peculiarities that make it difficult:
- Since it's a point-mass, you might expect that it would be a black hole. However, the sort of black hole that is studied most extensively, one with an "event horizon", is only possible with the constraint: [itex]Q^2 + \frac{J^2}{M^2} \leq M^2[/itex], where [itex]Q[/itex] is the charge, [itex]J[/itex] is the angular momentum, and [itex]M[/itex] is the mass (in some units). An electron violates this constraint, because its mass is so small compared with its charge and angular momentum. GR doesn't say that nothing can violate this constraint, but something that violates it will not have an event horizon. It will be a "naked singularity" I guess.
- As I understand it (which is not very well), standard General Relativity does not allow for point particles with intrinsic spin. This is a technical point that I really don't understand very well, but GR assumes that the stress-energy tensor, which is the source of spacetime curvature, is symmetric. If you have particles with nonzero intrinsic spin, the stress-energy tensor becomes nonsymmetric, and a generalization of GR is required.
TimeRip496 said:Do you mind telling me more about that event horizon? As far as I know, it is a border of a black hole at which light cannot escape upon crossing it.
TimeRip496 said:how do you obtain that equation?
TimeRip496 said:Do you mind telling me more about that event horizon? As far as I know, it is a border of a black hole at which light cannot escape upon crossing it. But how do you obtain that equation?
stevebd1 said:what would happen to the ergosphere in the case of an over-extremal black hole
seaocean1234 said:Do you mean Maxwell's equations?
seaocean1234 said:Doesn't electromagnetic shielding prove gravity is not an electromagnetic phenomenon.
PeterDonis said:There isn't one; in fact there isn't even a black hole any more in the super-extremal case, because there isn't an event horizon.
The Einstein field equation is a set of 10 equations that make up the cornerstone of Einstein's theory of general relativity. It relates the curvature of spacetime to the distribution of matter and energy.
The Einstein field equation was developed by Albert Einstein in 1915 as part of his theory of general relativity. It was a major breakthrough in understanding the nature of gravity and its effects on the universe.
The Einstein field equation is significant because it provides a comprehensive framework for understanding the relationship between gravity, matter, and energy in the universe. It has been tested and confirmed through numerous experiments and is widely accepted by the scientific community.
The Einstein field equation is used in a variety of scientific research, particularly in the fields of astrophysics and cosmology. It is used to study and explain phenomena such as black holes, gravitational waves, and the evolution of the universe.
While the Einstein field equation is a powerful and widely accepted theory, it does have its limitations. It does not account for the effects of quantum mechanics and is not compatible with other fundamental theories, such as the standard model of particle physics. Scientists are still working on developing a more complete theory that can unify all of these theories.