Dose of STEM: A Non-Terrifying Guide to Vacationing Near a Black Hole (Part 2)

How would Black Hole Civilisations Harness Energy?

Imagine a colony of advanced humans residing close to a black hole. They would probably be harvesting asteroids and dropping them into their black hole so that they can harness the released energy. They may also use other ways to harness the energy - like a black hole bomb.

Black Hole Bomb

To build a black hole bomb, the colony would require a black hole and a mirror. The process of harnessing energy through a black hole bomb involves shooting a beam of electromagnetic waves at the black hole. Some of the waves travel past the event horizon and disappear into the black hole. However, majority of the waves are amplified by the black hole’s rotational energy in the ergosphere, after which they will hit the surface of the mirror, reflect through the ergosphere and continue to amplify endlessly. This principle is called superradiant scattering.

Every time the waves bounce around, they get exponentially stronger, and the energy from the waves can be collected and used. This bomb could be a source of energy for trillions of years! If the waves are not released from the mirror envelope, they would keep getting more and more powerful, and the black hole bomb would explode. The explosion would release more energy than a supernova explosion. This explosion would probably be the biggest in the universe.

So, Are Black Hole Bombs Feasible?

As of now, no. But this is not science fiction. To build a black hole bomb would require a civilisation a thousand times more advanced than ours. On the Kardashev scale, we have still not reached the level at which we would be considered a Type - I civilisation. What is the Kardashev scale? In 1964, scientist Nikolai Kardashev developed the Kardashev scale to classify civilisations based on technological capabilities. The civilisations are classified into 4 main categories -

Type-I civilisation: A type-I civilisation would be able to use the available energy of its home planet to its full potential.
Type-II civilisation: A type-II civilisation would be able to use the energy of its solar system to its full potential.
Type-III civilisation: A type-III civilisation would be able to use the energy of its entire galaxy to its full potential.
Type-IV civilisation: A type-IV civilisation would be able to use the energy of multiple galaxies!

The Kardashev scale: 1 with a picture of the earth & sun, 2 with a picture of the solar system, 3 with a picture of the galaxy, and 4 with a picture of multiple galaxies

Today, humanity ranks at about 0.75 on the Kardashev scale. With our current technological capabilities, it would not be possible to build a black hole bomb, let alone a Dyson sphere. We would have to be a type-III civilisation for that.

Do you know any other way in which we can harness energy from black holes? What do you think black hole civilisations would look like? Comment down below!

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