Come to think of it, could black holes actually be used as an energy source? A setup like the one he describes would create a temperature gradient, and it's easy to extract power from that.
That would only make sense if this process somehow "depleted" the black hole; otherwise one could reverse entropy. IANA theoretical physicist so I don't know which mechanisms would be at work here.
If your blackhole is spinning, you can use its magnetic field as a source of energy. Eventually you will have robbed it of its spin, but that will take ... some time.
I wonder if black holes might be usable as cosmic-scale batteries. Suppose your civ was preparing to settle in for long-term survival into the super distant future. You might not need high amounts of energy, just a low constant supply for incredibly long amounts of time. You could drop a good percentage of a galaxy's mass into a black hole, then use the evaporated Hawking radiation over cosmological time scales to power your civ.
Suppose that the entities living inside this civ are simulations. A second to us might be tens of thousands of years to them, because their hardware processing runs very slowly because of the low amounts of available energy.
Or for young whipper-snapper civilizations who want to live faster, you could turn that black hole + galaxy-sized mass into a really big hydro-electric plant -- that is, power your civ from the potential energy.
Non-relativistically speaking (danger will robinson!), the photons emitted by the radiator have a huge gravitational potential associated with them. You're free, I believe, to extract that energy through a heat engine if you like, but I'm not sure the how feasible or efficient it would be.
I'm totally ignorant on the GR front; where's RobotRollCall?
Comments
That's a really good idea.
Come to think of it, could black holes actually be used as an energy source? A setup like the one he describes would create a temperature gradient, and it's easy to extract power from that.
That would only make sense if this process somehow "depleted" the black hole; otherwise one could reverse entropy. IANA theoretical physicist so I don't know which mechanisms would be at work here.
If your blackhole is spinning, you can use its magnetic field as a source of energy. Eventually you will have robbed it of its spin, but that will take ... some time.
I wonder if black holes might be usable as cosmic-scale batteries. Suppose your civ was preparing to settle in for long-term survival into the super distant future. You might not need high amounts of energy, just a low constant supply for incredibly long amounts of time. You could drop a good percentage of a galaxy's mass into a black hole, then use the evaporated Hawking radiation over cosmological time scales to power your civ.
Suppose that the entities living inside this civ are simulations. A second to us might be tens of thousands of years to them, because their hardware processing runs very slowly because of the low amounts of available energy.
Or for young whipper-snapper civilizations who want to live faster, you could turn that black hole + galaxy-sized mass into a really big hydro-electric plant -- that is, power your civ from the potential energy.
There's a lot of energy to be had simply in pushing black holes around 'til they crash into each other.
Non-relativistically speaking (danger will robinson!), the photons emitted by the radiator have a huge gravitational potential associated with them. You're free, I believe, to extract that energy through a heat engine if you like, but I'm not sure the how feasible or efficient it would be.
I'm totally ignorant on the GR front; where's RobotRollCall?
Microscopic black holes have been theorized as power sources for starships. The Hawking radiation becomes more intense, the smaller the black hole is.
http://en.wikipedia.org/wiki/Black_hole_starship