Renowned theoretical physicist Stephen Hawking said that if humans were able to find mini-black holes that have masses the size of mountains, it is theoretically plausible to harness them to power electricity on Earth.

Speaking at the BBC Reith Lectures, Hawking discussed concepts relating to black holes: what constructs them, the paradoxes behind their existence, and the possibility that these spacetime objects actually emit radiation.

Escaping A Black Hole

The true nature of what goes on inside a black hole remains one big, perplexing mystery for scientists. Because "black holes have no hair," scientists cannot tell from the outside what happens on the inside, apart from the object's electric charge, mass and rotation.

Black holes form after a star collapses in on itself when it has exhausted its nuclear fuel.

These spacetime regions are not easy to detect because they are not visible, but scientists infer the presence of black holes by studying their effects on surrounding matter. As such, light cannot escape black holes because the latter exhibit very strong gravitational forces.

This concept, however, was challenged by Hawking during his lecture.

Black holes contain information which are hidden to the outside. In this context, information constitutes the details of every particle and every force associated with an object. If this were true, this meant that black holes would glow like a piece of hot metal, but it was impossible.

Hawking found an answer to the problem. He discovered that black holes actually emit radiation, with a temperature that is inversely proportional to mass and directly proportional to surface gravity.

Quantum mechanics best explains the occurrence. It implies that everything in space is made up of pairs of virtual particles and anti-particles that are constantly materializing, and separating. Then, the separated pair would come together again, and annihilate one another.

In the presence of a black hole, Hawking said one member of the pair may fall into the hole, leaving the other without a partner. The remaining particle or antiparticle may follow its fallen partner, or escape to infinity. This would appear as if the escaping particle or antiparticle is being spat out by the black hole. This is called Hawking Radiation.

Harnessing A Mini-Black Hole

Hawking said a black hole with the mass of the sun would leak out radiation at a slow rate, and would be impossible to detect. There is also a black hole with a mass four million times as massive as that of the sun, and it is found at the center of the Milky Way.

It is different for smaller black holes, though. Hawking said a black hole with a mass of a mountain would emit gamma rays and X-Rays at a rate of approximately 10 million megawatts. This would be enough to supply the world's electricity.

Harnessing a mini-black hole would not be easy, unfortunately. It can't be kept at a power station, Hawking said, because it would drop to the floor and end up at the Earth's core. The only way to harness it is by having it orbit around our planet.

"People have searched for mini black holes of this mass, but have so far not found any," said Hawking. "This is a pity, because if they had I would have got a Nobel Prize."

That too, might change. If a team of scientists operating the Large Hadron Collider succeed in creating micro black holes, these would radiate particles that would help support the theory. If so, Hawking might receive his Nobel Prize after all.

Photo: Leslie Kommunikáció | Flickr

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