Adam Brown

The thing that Hawking and Bekenstein discovered in the 70s is that once quantum mechanics is involved, that's not true anymore.

Once quantum mechanics is involved, in fact, energy, even without you doing anything, starts to...

leave black holes.

The problem, as far as our distant descendants will be concerned, is that it leaves black holes extremely slowly.

So if you took a solar mass black hole, same mass as the sun, just collapsed to form a black hole, there'll be this little quantum, what's called Hawking radiation nowadays, little quantum Hawking radiation in which the energy will leach out again, very, very slowly.

And the temperature of a solar mass black hole is measured in nanokelvins.

So very,

low temperature.

So the energy leaches out when something that cold, you know, so cold you couldn't even see it in the cosmic background, it leaches out incredibly slowly back into the universe.

And that's bad news because it means the energy comes out super duper slowly.

So the mining question

is can you speed that up?

A solar mass black hole, if you don't help it, will take about 10 to the 55 times the current age of the universe to have given out all its energy back into the universe.

Can you make that faster?

And there were these proposals stretching back a few decades that you could.

You could do what's called mining black holes, where...

We see the Hawking radiation that escapes when we're a very long way away from the black hole.

But actually, mathematically, it's known that much of the Hawking radiation doesn't escape.

It just sort of makes it a little bit out of the black hole and then falls back in again.

And there was this proposal that you could reach in with a mechanical claw, obviously not crossing the horizon, because otherwise you've lost the claw and you're...