As in… if I shoot enough electrons at a black hole it will start to repel any negatively charged matter rather than attract it? No, that’d allow me to scout out information past the event horizon.
(Disclaimer: I’m not a physicist, so this may be BS.) This might not be a problem. If a black hole repels negative charges, all that tells you is the black hole’s position and net charge, and AFAIK that kind of information is allowed to ‘escape’ the black hole: position is OK because that’s frame-dependent, and the no-hair theorem says it’s OK to know the net charge.
If a black hole can be charged sufficiently that it repels an electron rather than attracts via gravity then:
There will be a point at which the gravity is perfectly balanced by the repulsion of the negative charges.
Just after that point there there will be a point where the electron is subject to a slight acceleration away from the center of the black hole.
If I shoot an electron at a suitable speed at such a black hole the electron will slow down and reverse in direction at a point determined by the initial speed and the acceleration. This point could be below the event horizon.
If such an election hit something inside the event horizon it would not return to me.
This tells me something about things inside the event horizon.
The teacher says I am not allowed to discover things about the inside of the event horizon.
Something in the above scenario must not be right.
I think you will find that the charge repulsion never exceeds the gravitational attraction in this way. The mass of a black hole places a bound on how much charge it can have; if the bound is exceeded, you get a naked singularity. You may actually be rediscovering this!
ETA: The two horizons you mentioned earlier merge when this bound is reached. I suppose this means that if you try to shoot a charge into one of these “extremal” black holes, the charge will be repelled outside the event horizon. That would be a consistent way for everything to work out, so that the bound can never be violated. But I will have to check.
I suppose this means that if you try to shoot a charge into one of these “extremal” black holes, the charge will be repelled outside the event horizon.
You could be right, but how? I inject enough electrons into the black hole to maintain it at as high a charge as possible. Then I launch more electrons from a platform that is doing a slighshot pass right by the event horizon. And I dedicate the energy from a nearby star to shooting photons at it to force the extra particles in...
And even forgetting extreme options. Just why? If the black hole is not charged to a level that will repel electrons it will attract them. Add more and they will just hover there without accelerating. Add more still and they will be repelled. This works unless weird math comes in to play.
Red suggests discharge via Hawking radiation. I would not be able to rule out some sort of asymptotic increase in Hawking Radiation discharge toward my electron input rate. (Basically because I don’t know how Hawking Radiation works.)
I had never heard the term before but that is just where my thoughts were leading me.
Looking a bit more closely it would seem that ‘strong’ forces would ensure there is always at least a tiny horizon at which even electrons couldn’t escape no matter what the charge. (And if there wasn’t the thing would fall apart). It just doesn’t matter how big you make the charge. ‘Squared’ just doesn’t cut it. So while the electrons would return from where even photons could not escape they would still get stuck if they went deep enough. But I don’t know where things like strong forces start to break down...
(Disclaimer: I’m not a physicist, so this may be BS.) This might not be a problem. If a black hole repels negative charges, all that tells you is the black hole’s position and net charge, and AFAIK that kind of information is allowed to ‘escape’ the black hole: position is OK because that’s frame-dependent, and the no-hair theorem says it’s OK to know the net charge.
I am just speaking BS too but:
If a black hole can be charged sufficiently that it repels an electron rather than attracts via gravity then:
There will be a point at which the gravity is perfectly balanced by the repulsion of the negative charges.
Just after that point there there will be a point where the electron is subject to a slight acceleration away from the center of the black hole.
If I shoot an electron at a suitable speed at such a black hole the electron will slow down and reverse in direction at a point determined by the initial speed and the acceleration. This point could be below the event horizon.
If such an election hit something inside the event horizon it would not return to me.
This tells me something about things inside the event horizon.
The teacher says I am not allowed to discover things about the inside of the event horizon.
Something in the above scenario must not be right.
I think you will find that the charge repulsion never exceeds the gravitational attraction in this way. The mass of a black hole places a bound on how much charge it can have; if the bound is exceeded, you get a naked singularity. You may actually be rediscovering this!
ETA: The two horizons you mentioned earlier merge when this bound is reached. I suppose this means that if you try to shoot a charge into one of these “extremal” black holes, the charge will be repelled outside the event horizon. That would be a consistent way for everything to work out, so that the bound can never be violated. But I will have to check.
You could be right, but how? I inject enough electrons into the black hole to maintain it at as high a charge as possible. Then I launch more electrons from a platform that is doing a slighshot pass right by the event horizon. And I dedicate the energy from a nearby star to shooting photons at it to force the extra particles in...
And even forgetting extreme options. Just why? If the black hole is not charged to a level that will repel electrons it will attract them. Add more and they will just hover there without accelerating. Add more still and they will be repelled. This works unless weird math comes in to play.
Red suggests discharge via Hawking radiation. I would not be able to rule out some sort of asymptotic increase in Hawking Radiation discharge toward my electron input rate. (Basically because I don’t know how Hawking Radiation works.)
I had never heard the term before but that is just where my thoughts were leading me.
Looking a bit more closely it would seem that ‘strong’ forces would ensure there is always at least a tiny horizon at which even electrons couldn’t escape no matter what the charge. (And if there wasn’t the thing would fall apart). It just doesn’t matter how big you make the charge. ‘Squared’ just doesn’t cut it. So while the electrons would return from where even photons could not escape they would still get stuck if they went deep enough. But I don’t know where things like strong forces start to break down...
BTW, it seems that charged black hole will discharge via Hawking radiation.