Stephen Hawking has said that mini black holes could potentially provide enough energy to supply the world's electricity demands – but could also destroy the planet. He made these comments as part of the BBC's Reith lectures. The special series on black holes looks at the physicist's ideas about these collapsed stars from which nothing can escape.
In the latest talk – a full transcript of which can be found here – Hawking said that 'mini' black holes, with the same mass of a mountain, would give off enough electricity to power the planet.
"There could be much smaller mini black holes with the mass of say, a mountain," he said. "A mountain-sized black hole would give off X-rays and gamma rays, at a rate of about 10 million megawatts, enough to power the world's electricity supply. It wouldn't be easy however, to harness a mini black hole. You couldn't keep it in a power station, because it would drop through the floor and end up at the centre of the Earth. If we had such a black hole, about the only way to keep hold of it would be to have it in orbit around the Earth. People have searched for mini black holes of this mass, but have so far not found any. This is a pity, because if they had I would have got a Nobel Prize."
However, all is not lost, he said. Some theories say we could a mini black hole on Earth with the extra dimensions of space-time – where the universe we experience is a four-dimensional surface in a 10-dimensional space, for example. He said the film Interstellar provided a picture of this – the extra dimensions would not be visible because light would not propagate through them. This suggests that we only see the four dimensions of our universe.
"Gravity, however, would affect the extra dimensions and would be much stronger than in our universe. This would make it much easier to form a little black hole in the extra dimensions. It might be possible to observe this at the LHC, the Large Hadron Collider, at CERN in Switzerland. This consists of a circular tunnel, 27 kilometres [16.8 miles] long. Two beams of particles travel round this tunnel in opposite directions, and are made to collide. Some of the collisions might create micro black holes. These would radiate particles in a pattern that would be easy to recognise. So I might get a Nobel Prize after all."