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How To Destroy a Black Hole
KentuckyFC writes "The critical concept that makes a black hole black is the event horizon: a theoretical boundary in space through which light and other objects can pass in one direction but not the other. Since light cannot escape the event horizon, it must be black. The event horizon is a nuisance to astrophysicists because it hides the interesting new physics that must go on inside a black hole. What they would like is a way to get rid of the event horizon so that they can see what goes on behind it. It turns out that just such a thing may be possible, say physicists. According to the mathematics of general relativity, the event horizon should disappear if a black hole were fed enough charge and angular momentum relative to its mass. However the calculations are so fiendish (PDF) that nobody knows whether the black hole would shed this extra angular momentum and charge before it could settle into a stable 'naked' state. However, the possibility that the event horizon could be destroyed raises the question of what astrophysicists would see behind this veil. According to some, black holes are regions of spacetime with infinite curvature called singularities. Many believe that 'naked' singularities cannot exist in nature. And yet there are enough question marks to suggest that this mystery is far from settled."
One of the problems with approaching a black hole (aside from massive amounts of radiation around ones actively eating matter) is the fact that the force of gravity increases as you approach the mass responsible for the gravity.
With small black holes, as you approach (feet first) the difference in gravitational pull at your feet would be many times larger than the gravitational pull at your head. You would be literally ripped apart, down to the molecular level. This is known as "Spaghettification".
http://en.wikipedia.org/wiki/Spaghettification
However, with a large enough black hole, you should be able to pass the event horizon before these tidal forces grow large enough to rip you apart. Of course, this does you no good, because once you are inside the event horizon you cannot exert a great enough force to prevent yourself from falling deeper until the forces ARE great enough to rip you apart.
But for a large black hole, in theory, you could cross the event horizon without being ripped apart.
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Although no one knows what happens at the end point of black hole evaporation it is unlikely it would leave a naked singularity since the mass of the singularity is what is being 'evaporated'. Besides, even if there was a naked singularity around just before the thing evaporates it would be kicking out so much energy you wouldn't be able to get anywhere near it. A 1kg black hole evaporating would release the equivalent energy to a large thermonuclear weapon in a fraction of a second.
(Disclaimer: I Am A Physicist, but this is not my area of expertise, and only the experts understand those equations.)
It's not feeding it mass that does the trick; it's feeding it charge and angular momentum. The only reason you feed it more mass is because you need mass to carry the charge and momentum into the hole.
What you get if you feed it charge and angular momentum is a spinning monopole. I think they are postulating that a spinning monopole causes rotational frame dragging, and if you do it right you can get the charged frame dragging effects to cancel out the gravitational effects -- namely, the event horizon.
After you do all that, what will be left? Like the article says, nobody knows. That's why it's exciting.
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Ding ding ding - we have a winner. This is the point that so many cosmology shows on Discovery Channel or Science Channel (or whatever) completely fail to mention; they keep describing black holes as "so massive, even light can't escape" without explaining why (Michio Kaku, Alex Fillipenko, (sp) I'm looking at you). See Wikipedia for the details, but the important point is that escape velocity is dependent on an object's mass divided by its radius. So if mass goes high enough, or radius low enough, you get an escape velocity greater than the speed of light: AKA an event horizon.
... the place where the escape velocity equals the speed of light.
Say it again, and remember it later:
The event horizon is
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