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DanielLC comments on Stupid Questions December 2014 - Less Wrong
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How do they propose to move the blackholes? Nothing can touch a blackhole, right?
It can, as long as you don't mind that you won't get it back when you're done. You have to constantly fuel the black hole anyway. Just throw the fuel in from the opposite direction that you want the black hole to go.
Throwing mass into a black hole is harder than it sounds. Conveniently sized black holes that you actually would have a chance at moving around are extremely small, much smaller than atoms, I believe. I think they would just sit there without eating much, despite strenous efforts at feeding them. The cross-section is way too small.
To make matters worse, such holes would emit a lot of Hawking radiation, which would a) interfere with trying to feed them, and b) quickly evaporate them ending in an intense flash of gamma rays.
The problem is throwing mass into other mass hard enough to make a black hole in the first place.
Hawking radiation isn't a big deal. In fact, the problem is making a black hole small enough to get a significant amount of it. An atom-sized black hole has around a tenth of a watt of Hawking radiation. I think it might be possible to get extra energy from it. From what I understand, Hawking radiation is just what doesn't fall back in. If you enclose the black hole, you might be able to absorb some of this energy.
Yes, making them would be incredibly hard, and because of their relatively short lifetimes, it would be extremely surprising to find any lying around somewhere. Atom sized black holes would be very heavy and not produce much Hawking readiation, as you say. Smaller ones would produce more Hawking radiation, be even harder to feed, and evaporate much faster.