- #1
nightcleaner
I don't know a lot about this topic so corrections are solicited.
My understanding is that black holes evaporate by Hawking radiation. Hawking radiation, by my reading, occurs when a pair of virtual particles emerges very close to but just outside the event horizon of the black hole. When they emerge (from quantum foam, not from the BH) one of the pair may occur closer to the event horizon, the other further from it. In some cases, this difference is just right to cause one of the virtual particles to enter the event horizon, while the other escapes into our universe.
Normally virtual particles immediately anihiliate each other, but in this case, as they are seperated, they do not immediately anihiliate. In fact, the particle which is free to enter our universe is really no different than any other particle in this regard, and may expect to have the same half-life other particles of its kind enjoy. This would be a cause for concern, since it appears to violate the conservation of mass, since a "new" particle is created and enters our universe.
To explain this apparent violation of conservation of mass, one only has to realize that the particle which enters our universe is matched by an anti-particle which goes into the closed and very small region of the BH. Because this region is closed and very small, particles entering it soon encounter the other particles that are trapped in there. On average, any particle resulting from the stripping of a virtual pair will soon encounter its anti-particle which has been stripped from another pair, and these two will anihiliate. When they do, conservation of mass is restored, since the infall anihiliation accounts for two particles radiated.
Last night while boiling out the deep fryer I was thinking about this, from the point of view of infall. Now it happens that the information ie mass, contained by a BH is proportional to its surface area, not its volume as one might assume. This is because we cannot know what goes on inside a black hole, but we can have an idea anyway of conditions on its surface. The seeming contradiction here is due to the distortion of time near an event horizon.
If we hover outside the event horizon and lob rocks into it, we could watch the rocks as they fall in. But we don't see them enter the event horizon. Instead, they seem to go slower and slower as approach the horizon, and at the same time they grow dimmer and dimmer, and their escaping photons become weaker and weaker, the energy waves longer and longer, until after a while we do not have any quanta from the rocks at all. But during the time that we can watch them, they do not enter the horizon at all, but seem to us to slow down and stop right at the horizon.
So, from our perspective outside the horizon, everything that goes into the event horizon seems to just hang there until we can't see it any more. This is why we can surmize that all the information that goes into a black hole is right there on the surface, and, as far as we are concerned, does not proceed any deeper.
Another way to look at this is to consider that time, viewed from the outside, seems to stop for the infalling object. The infalling object wouldn't see it that way, but from the outside, looking in, that is what we see. In a sense, as far as we are concerned, the infalling object becomes eternal and no longer changes in time as we do. It no longer shows any indication of ageing, moving or reacting.
So that's the puzzle. If, as far as we are concerned, the object as it infalls attains an eternal state, then it cannot, as far as we are concerned, react with its antiparticle on the inside to produce the required mass loss to counter the mass gain resulting from the radiated partner.
Our universe, then, must experience a net gain of mass and energy, upsetting the mass conservation applecart. We now have to look for a sink somewhere else where mass is lost from the universe to restore our precious conservation.
But this is not what concerns me immediately. My immediate concern has to do with the supposed loss of mass of the Black Hole to evaporation, which seems to depend upon the anihiliation of particles enclosed within the horizon. This loss, when calculated, yields an evaporation time for small black holes which is pretty fast, say about 10^-23 seconds. A small black hole doesn't have enough time, at that rate, to interact with much else in the universe. It is not likely, for example, that a small black hole would suck up the Earth's atmosphere, or fall to the center of the Earth and give another revival to the hollow Earth theories. It just can't last long enough to get the matter it needs to stay alive.
However, the analysis above may change that scenario back again to threat status. If my reading is correct, the balanceing act of particle extinction within the black hole does not happen until sometime in the extremely distant future. If that is so, the black hole will not be seen to evaporate, but will continue to have opportunities to encounter some mighty tastey bananas at our expense for a long, long time. The first black hole we create on the planet will indeed have a chance to swallow us all up.
I should very much like to hear an argument that counters this unfortunate scenario.
Thanks,
nc
My understanding is that black holes evaporate by Hawking radiation. Hawking radiation, by my reading, occurs when a pair of virtual particles emerges very close to but just outside the event horizon of the black hole. When they emerge (from quantum foam, not from the BH) one of the pair may occur closer to the event horizon, the other further from it. In some cases, this difference is just right to cause one of the virtual particles to enter the event horizon, while the other escapes into our universe.
Normally virtual particles immediately anihiliate each other, but in this case, as they are seperated, they do not immediately anihiliate. In fact, the particle which is free to enter our universe is really no different than any other particle in this regard, and may expect to have the same half-life other particles of its kind enjoy. This would be a cause for concern, since it appears to violate the conservation of mass, since a "new" particle is created and enters our universe.
To explain this apparent violation of conservation of mass, one only has to realize that the particle which enters our universe is matched by an anti-particle which goes into the closed and very small region of the BH. Because this region is closed and very small, particles entering it soon encounter the other particles that are trapped in there. On average, any particle resulting from the stripping of a virtual pair will soon encounter its anti-particle which has been stripped from another pair, and these two will anihiliate. When they do, conservation of mass is restored, since the infall anihiliation accounts for two particles radiated.
Last night while boiling out the deep fryer I was thinking about this, from the point of view of infall. Now it happens that the information ie mass, contained by a BH is proportional to its surface area, not its volume as one might assume. This is because we cannot know what goes on inside a black hole, but we can have an idea anyway of conditions on its surface. The seeming contradiction here is due to the distortion of time near an event horizon.
If we hover outside the event horizon and lob rocks into it, we could watch the rocks as they fall in. But we don't see them enter the event horizon. Instead, they seem to go slower and slower as approach the horizon, and at the same time they grow dimmer and dimmer, and their escaping photons become weaker and weaker, the energy waves longer and longer, until after a while we do not have any quanta from the rocks at all. But during the time that we can watch them, they do not enter the horizon at all, but seem to us to slow down and stop right at the horizon.
So, from our perspective outside the horizon, everything that goes into the event horizon seems to just hang there until we can't see it any more. This is why we can surmize that all the information that goes into a black hole is right there on the surface, and, as far as we are concerned, does not proceed any deeper.
Another way to look at this is to consider that time, viewed from the outside, seems to stop for the infalling object. The infalling object wouldn't see it that way, but from the outside, looking in, that is what we see. In a sense, as far as we are concerned, the infalling object becomes eternal and no longer changes in time as we do. It no longer shows any indication of ageing, moving or reacting.
So that's the puzzle. If, as far as we are concerned, the object as it infalls attains an eternal state, then it cannot, as far as we are concerned, react with its antiparticle on the inside to produce the required mass loss to counter the mass gain resulting from the radiated partner.
Our universe, then, must experience a net gain of mass and energy, upsetting the mass conservation applecart. We now have to look for a sink somewhere else where mass is lost from the universe to restore our precious conservation.
But this is not what concerns me immediately. My immediate concern has to do with the supposed loss of mass of the Black Hole to evaporation, which seems to depend upon the anihiliation of particles enclosed within the horizon. This loss, when calculated, yields an evaporation time for small black holes which is pretty fast, say about 10^-23 seconds. A small black hole doesn't have enough time, at that rate, to interact with much else in the universe. It is not likely, for example, that a small black hole would suck up the Earth's atmosphere, or fall to the center of the Earth and give another revival to the hollow Earth theories. It just can't last long enough to get the matter it needs to stay alive.
However, the analysis above may change that scenario back again to threat status. If my reading is correct, the balanceing act of particle extinction within the black hole does not happen until sometime in the extremely distant future. If that is so, the black hole will not be seen to evaporate, but will continue to have opportunities to encounter some mighty tastey bananas at our expense for a long, long time. The first black hole we create on the planet will indeed have a chance to swallow us all up.
I should very much like to hear an argument that counters this unfortunate scenario.
Thanks,
nc