- #1
jonmtkisco
- 532
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1. As a thought experiment, imagine a region of space which (inexplicably) is very densely filled with electrons and contains no other matter. Gravity would drive collapse towards a singularity, but electromagnetism would cause the electrons to repulse each other. Since electromagnetic potential is far stronger than gravitational potential per unit of mass, is it impossible for such a collection of electrons to self-collapse into a black hole, regardless of the density of the electron cloud? My guess is that it is impossible.
2. Now let's imagine a region of space filled very densely with (electrically neutral) dust. Gravity causes the dust cloud to collapse, but then random motions and interactions. cause the dust cloud to virialize. If dust continues to infall into this region (from "outside"), thereby increasing its density indefinitely, and the newly infalling dust also virializes, is there any density threshold at which the total gravity of dust would "overcome" the virial resistance and cause the cloud to collapse into a black hole? (No gravity waves or external perturbations are allowed in this exercise). My guess is that the dust cloud would continue to virialize more and more with ever increasing angular momentum, withstanding collapse until the virial motion reaches a significant percentage of the speed of light, at which time the energy required to further increase the angular momentum would grow (due to special relativity) to the point where the cloud collapses into a black hole rather than gaining further angular momentum.
Jon
2. Now let's imagine a region of space filled very densely with (electrically neutral) dust. Gravity causes the dust cloud to collapse, but then random motions and interactions. cause the dust cloud to virialize. If dust continues to infall into this region (from "outside"), thereby increasing its density indefinitely, and the newly infalling dust also virializes, is there any density threshold at which the total gravity of dust would "overcome" the virial resistance and cause the cloud to collapse into a black hole? (No gravity waves or external perturbations are allowed in this exercise). My guess is that the dust cloud would continue to virialize more and more with ever increasing angular momentum, withstanding collapse until the virial motion reaches a significant percentage of the speed of light, at which time the energy required to further increase the angular momentum would grow (due to special relativity) to the point where the cloud collapses into a black hole rather than gaining further angular momentum.
Jon