3 ms·

> but then you have to explain why the mass is in a shell, rather than collapsing in on itself. That is an easy one. It is the only "stable" configuration giv

by keenerd 11y ago

> but then you have to explain why the mass is in a shell, rather than collapsing in on itself. That is an easy one. It is the only "stable" configuration given two pieces of information: 1) The force of (and therefor effects of) gravity of a sphere is maximum on the surface and tapers to zero at the center. 2) Time (and therefor motion) all but stops at when the force of gravity reaches black-hole proportions. So the center becomes an unstable region of low density and rapid time/motion, and the surface becomes a stable region of treacle-time. A hollow sphere would be the result. That said it is almost certainly wrong because it is sufficiently simple that every pop-culture astrophysicist would have written about it, and none have.

akiselev 11y ago
The net force on a particle due to gravity tapers towards the center but the pull of gravity on the surrounding particles accumulates into pressure preventing any lower density from forming on the interior unless there is another force like fusion providing outward pressure. Since black holes form after gravitational collapse that is no longer possible. The only natural equivalent I can think of would be rotational vorteces (tornadoes) but the "shell" would be two dimensional and such a system requires two fluids with different properties, which couldn't exist in the black hole.
- keenerd 11y ago
  > the pull of gravity on the surrounding particles accumulates into pressure preventing any lower density from forming on the interior unless there is another force ... providing outward pressure. (Keep in mind I don't believe this, it is just fun to argue cute ideas from basic principles.) In this case the secondary force would be time dilation. Assuming that black holes have finite density, there must be a second event horizon inside the body. Just as a particle can't escape the surface going upwards, particles inside the black hole would not be able to escape downwards, if between the two horizons. While the force of gravity would still pull particles towards the center and away from the interior horizon, any brownian motion away from the center is self-reinforcing since the particle moves towards a region of greater time dilation. There would be an intermediary unstable stage like a nut rattling around inside a shell, but the slightest instability would start the core oscillating, and each time it brushes the shell it loses a bit more mass. When matter approaches an event horizon it tends to release a lot of energy, repeatedly breaking up (or boiling off) the core and launching bits of it into the shell. This provides a another source of outward pressure. Reiterating: this is likely complete poppycock. edit: Ah, I see the snag. There isn't a second event horizon inside the black hole. Just because opposing gravitational forces cancel each other out in the center (and space is flat there) does not mean time is any less distorted by all the surrounding mass.
  - akiselev 11y ago
    >> edit: Ah, I see the snag. There isn't a second event horizon inside the black hole. Just because opposing gravitational forces cancel each other out in the center (and space is flat there) does not mean time is any less distorted by all the surrounding mass. Exactly. The relationship between mass, space, and time is complicated but there is a causal link going (roughly) in the direction of mass -> space -> time. The presence of mass warps space which dilates time (ignoring special relativity and quantum gravity which makes it weirder). The combined effects of the gravitational force (pressure) necessitates an increase in density, which further warps space, which further dilates time around the singularity. Time dilation isn't "fighting" the force of gravity and the warping of space, it is an observational effect that is only meaningful outside of the reference frame of the singularity. All other forces and phenomenon are already dependent on time so if the laws of nature do exist inside of a singularity, the existence of other effects like brownian motion will be entirely dependent on the mass/gravitational forces (aka they likely wouldn't be relevant due to the overwhelming effect of compressing matter and energy to such a small volume).

by keenerd 11y ago

akiselev 11y ago

The net force on a particle due to gravity tapers towards the center but the pull of gravity on the surrounding particles accumulates into pressure preventing any lower density from forming on the interior unless there is another force like fusion providing outward pressure. Since black holes form after gravitational collapse that is no longer possible. The only natural equivalent I can think of would be rotational vorteces (tornadoes) but the "shell" would be two dimensional and such a system requires two fluids with different properties, which couldn't exist in the black hole.

keenerd 11y ago
> the pull of gravity on the surrounding particles accumulates into pressure preventing any lower density from forming on the interior unless there is another force ... providing outward pressure. (Keep in mind I don't believe this, it is just fun to argue cute ideas from basic principles.) In this case the secondary force would be time dilation. Assuming that black holes have finite density, there must be a second event horizon inside the body. Just as a particle can't escape the surface going upwards, particles inside the black hole would not be able to escape downwards, if between the two horizons. While the force of gravity would still pull particles towards the center and away from the interior horizon, any brownian motion away from the center is self-reinforcing since the particle moves towards a region of greater time dilation. There would be an intermediary unstable stage like a nut rattling around inside a shell, but the slightest instability would start the core oscillating, and each time it brushes the shell it loses a bit more mass. When matter approaches an event horizon it tends to release a lot of energy, repeatedly breaking up (or boiling off) the core and launching bits of it into the shell. This provides a another source of outward pressure. Reiterating: this is likely complete poppycock. edit: Ah, I see the snag. There isn't a second event horizon inside the black hole. Just because opposing gravitational forces cancel each other out in the center (and space is flat there) does not mean time is any less distorted by all the surrounding mass.
- akiselev 11y ago
  >> edit: Ah, I see the snag. There isn't a second event horizon inside the black hole. Just because opposing gravitational forces cancel each other out in the center (and space is flat there) does not mean time is any less distorted by all the surrounding mass. Exactly. The relationship between mass, space, and time is complicated but there is a causal link going (roughly) in the direction of mass -> space -> time. The presence of mass warps space which dilates time (ignoring special relativity and quantum gravity which makes it weirder). The combined effects of the gravitational force (pressure) necessitates an increase in density, which further warps space, which further dilates time around the singularity. Time dilation isn't "fighting" the force of gravity and the warping of space, it is an observational effect that is only meaningful outside of the reference frame of the singularity. All other forces and phenomenon are already dependent on time so if the laws of nature do exist inside of a singularity, the existence of other effects like brownian motion will be entirely dependent on the mass/gravitational forces (aka they likely wouldn't be relevant due to the overwhelming effect of compressing matter and energy to such a small volume).