- #1
Phrak
- 4,267
- 6
Does a Schwartzchild black hole have a singularity at its center?
That is one of the big problems of current physics. General relativity predicts there is one, Quantum theory won't allow it. The reconciliation of these two main theories of modern physics is the impetus (not necessarily the only one) for theories such as string theory and loop quantum gravity.Phrak said:Does a Schwartzchild black hole have a singularity at its center?
Jonathan Scott said:Note that General Relativity and Einstein's field equations do NOT actually directly predict the existence or otherwise of black holes, contrary to popular opinion. In the solutions of those equations described by the Schwarzschild solution and later extensions such as the Kerr solution for rotating central bodies, the radial coordinate involves a constant of integration which is determined by assumed boundary conditions. Karl Schwarzschild himself derived his solution using a Euclidean radial coordinate, making the assumption that a point mass was located at the origin, but then pointed out that the mathematics for describing the solution could be simplified by using a different radial coordinate which had a value of 2GM at the physical origin. (See arXiv:physics/9905030 for a translation of Schwarzschild's original paper). When Hilbert later described Schwarzschild's solution, he did it directly in terms of the simplified coordinate system, but assumed that the physical origin was where Schwarzschild's modified radial coordinate was zero rather than 2GM.
It is this assumption which gives rise to the possibility of black holes, and for a long time it seems that no-one noticed that any assumption had been made, until Leonard S Abrams dared to point this out in 1989 (arXiv:gr-qc/0102055). Unfortunately, as there doesn't seem to be any obvious way to prove which boundary assumption is better, this has given rise to various surprisingly fierce battles based on somewhat unsatisfactory arguments which appear to boil down to "my assumptions are better than your assumptions".
George Jones said:These ideas have been thoroughly discredited; see
https://www.physicsforums.com/showthread.php?t=141985&highlight=Abrams
http://arxiv.org/abs/gr-qc/0608033.
Phrak said:In a vernacular way, it would be rather scitzoid if the particle crossed the event horizon in one coordinate system, and not another.
Phrak said:In a vernacular way, it would be rather scitzoid if the particle crossed the event horizon in one coordinate system, and not another.
George Jones said:The particle crosses the event horizon in all coordinate systems that cover the event horizon; Schwarzschild coordinates do not cover the even horizon.
A Schwarzchild blackhole is a type of blackhole predicted by Einstein's theory of general relativity. It is a region of space where the gravitational pull is so strong that nothing, including light, can escape from it.
A Schwarzchild blackhole is formed when a massive star dies and its core collapses under its own gravity. As the star's core collapses, it becomes infinitely dense and its gravity becomes so strong that it creates a singularity at its center, forming a blackhole.
A singularity is a point of infinite density and zero volume at the center of a Schwarzchild blackhole. In this point, the laws of physics, as we know them, break down, making it impossible to predict what happens inside a blackhole.
No, nothing can escape from a Schwarzchild blackhole. Once something crosses the event horizon (the point of no return), it is pulled into the blackhole and cannot escape. This includes light, which is why blackholes are invisible.
The existence of a singularity in a Schwarzchild blackhole is a theoretical prediction of general relativity, but it has not been confirmed by observational evidence. Some scientists believe that a more complete theory, such as quantum gravity, may provide a different understanding of blackholes and their singularities.