The Black Hole Bomb and Black Hole Civilizations

The Black Hole Bomb and Black Hole Civilizations


Black holes are the largest collections of pure violent energy in the universe. If you come too close, they’ll devour you and add your energy to their collection. And so, the energy is lost to us forever. Or is it? It turns out there’s a universe cheat code. A way of powering civilizations until the very death of everything, or of constructing the largest bomb in the universe. But how? Didn’t we learn that all energy is trapped forever in black holes, even light? This is true. Everything you think you know about the weirdest thing in the universe is about to get weirder, for one simple reason: Black holes are spinning. When really really massive stars die, their cores collapse under their own gravity into black holes. This means something very big becomes very, very tiny. Like the tiniest anything can be in this universe. But stars are rotating and a fundamental property of our universe is that things that are spinning don’t want to stop spinning. We call this: angular momentum. And this angular momentum can’t go away. A big thing that spins and becomes smaller, spins faster. So, as the core of a star collapses, its momentum makes it spin faster and faster and faster, until it collapses into a black hole . And the black hole keeps on spinning, inconceivably fast. Some of them spin millions of times a second. Just like non spinning black holes, …spinning black holes have an event horizon and a singularity at their core, where all of their mass is concentrated. The singularity is usually described as a single infinitely small point with no surface area. But points can’t rotate, so a rotating singularity can’t be a point. Instead, it’s a RINGularity. A ringularity is a ring with a thickness of zero and no surface, spinning extremely fast, containing all the mass of the black hole. The black hole is spinning so fast, that it morphs space and time itself. It literally drags space with it, such is its power. This creates a new and super weird region of space-time: the Ergosphere, which envelops the black hole. If space and time are completely broken inside the event horizon, then they’re only half broken inside the ergosphere. Inside the ergosphere, nothing makes sense. It’s possible to enter it and then leave it again, but it’s probably not a great experience. You can imagine it like this: Falling into a static black hole is like sliding down a hole. Being inside the ergosphere of a spinning black hole is like spiraling down a deadly drain. The black hole transfers its own kinetic energy in the form of rotation, to everything that enters the ergosphere. The ringularity makes you dance whether you want to or not. You need to move faster than the speed of light just to stand still here, which is impossible. But here’s our cheat code: We can steal this energy, and there’s a lot of energy to steal. Take the supermassive black hole at the center of the Milky Way. We could steal as much energy from it as every single star in the Milky Way emits in a billion years combined. The easiest way to steal this energy is, oddly enough, to drop something into the black hole. We’ve seen that the ringularity forces energy on us when we enter the ergosphere, …which is a lot like being in a whirlpool, with space-time rushing around and around. If you’re clever you can use the water to your advantage, and swim faster than before. In practice, this means sending a rocket into the ergosphere, and making a trade with the black hole: We give it some mass-energy, and it gives us some of its rotational energy. But it’s not a fair trade, we get the better deal. Normally, if you fire a rocket, you exchange chemical energy for kinetic energy. This is like pushing yourself forward in a swimming pool. But if you fire a rocket inside the ergosphere, it’s like pushing yourself forward in a wave pool. The rotational energy of the waves gives you a much stronger boost than you could get just by pushing yourself. The boost from the rotation of the back hole is so big, that you leave the ergosphere with much more energy than you entered it. The black hole gives a tiny amount of its rotational energy to you, and slows down a little. Obviously, this requires a lot of food. Fortunately, black holes aren’t picky eaters. An advanced future civilization would probably harvest asteroids to drop them into the black hole when they needed an energy boost. But there’s an even better way to get energy from a black hole, and oddly enough, it builds the biggest bomb any living thing could ever hope to build: We only need two things to build a black hole bomb: a fast-spinning black hole, and a big mirror. The mirror has to completely envelop the black hole, …which is similar to a Dyson Sphere, a mega structure that harvests the energy of an entire star. Although, our mirror would be easier to build. Mirrors are simpler, and black holes are much, much more compact than stars. If we made the mirror 10 centimeters thick, the metal of a big asteroid would probably be enough material for a black hole with the mass of our Sun. Once our mirror is in place, we only need to open a window, and shoot electromagnetic waves at the black hole. You can imagine what happens next, by imagining tossing a ball at a wall, and it coming back faster than a bullet. The waves hit the black hole at light speed. A small proportion of the waves falls past the event horizon to disappear forever. But a much larger amount sloshes through the ergosphere, …where the black hole forces some of its rotational energy on them, and amplifies them. They now begin superradiant scattering, which are fancy science words meaning: “Bouncing around between mirror and black hole and getting stronger.” Every time they go around, they are getting exponentially stronger. By opening some windows in the mirror, we can extract the energy from the waves as fast as they grow. Which we could use, in theory, to create what would be for all practical purposes, an endless source of energy for trillions of years. Or, we could blow it up. If the waves are not released, they will continue to get stronger and stronger, …and take more and more energy from the black hole, until the mirror shatters. A supermassive black hole would release as much energy as a supernova, …making the bomb the largest explosion any living being could ever create. The beauty of the black hole bomb, the Penrose process, and the super radiant scattering, is that they are not science-fiction. In the far far future, this might be the only way to survive in our dying universe. After all the red dwarfs have cooled down, and all the white dwarfs transformed into black dwarfs, the universe will turn dark forever. Rotating black holes might be the only sources of energy in the entire universe that life could harvest. If so, the last living being in existence might one day end its life around a black hole. Which is equally chilling and uplifting. It turns out that even without any light, there are places we can go. Black holes are as interesting as they are mysterious, but there’s actually a surprising amount we do know. Using math we can calculate things and come up with theories about how we die if we fall into them. If you’re the sort of person who gets excited about maths and calculating these things for yourself, …our friends at Brilliant have put together a fantastic black hole quiz to help you get your head around them. Brilliant is a problem-solving website that teaches you to think like a scientist, by guiding you through the problems. They take concepts like these, break them up into bite-sized pieces, present clear thinking in each part, and then build back up to an interesting conclusion. If you visit Brilliant.org/nutshell or click the link in the description, you can sign up for free and learn all kinds of cool stuff. And as a bonus for Kurzgesagt viewers, the first 688 people will also get 20% off their annual membership. If you want to truly learn about black holes and support Kurzgesagt, this is one of the best ways to do it.

100 Replies to “The Black Hole Bomb and Black Hole Civilizations”

  1. It would be ideal for waste management especially nuclear waste. Convert waste to energy. The idea that it could be contained and controlled in a dyson sphere is laughable. The energy and heat would get so intense it would blow up on its own pretty quickly. I don't even think you'd have time to build the sphere before the energy contained would explode out. You really think you can contain the electromagnetic field or release it fast enough? lol.

  2. instead of a 100% mirror put a slightly see through mirror and shoot a light wave inside. the light will radiate out side the mirror and provide an immensely bright light

  3. The thing about black holes I dont understand is not the explanations of black holes it's the fact we say what it's like to be inside or near or around yet noone has even been within the same thinking distance of one.

  4. While the media around the world is doing its best to convince us that blackholes will be the last known source of energy for civilization . . they are forgetting the fact that us humans/living things are proof that entropy is not the only way the universe grow old. The idea of creating something from nothing (splitting matter and dark matter from 0) has not picked up interest, but it is the ultimate reality of existence.

  5. So, finally we have a solution to the Fermi paradox: A planet-destoyer bomb is possible. Just make a micro black hole and contain its energy until it explodes. Sooner or later some maniac on Earth will build it when the technology sufficiently adavanced, maybe in a 1000 yrs. And sooner or later (another) maniac will detonate it. Goodbye Earth.

  6. i am HIGHLY skeptical

    1. how would you build it without it being sucked up
    2. how would it be strong enough to not be ripped apart (far before supernova strength)
    3. we have not even colonized the moon, and you're already planning harvesting energy from black holes?
    4. no

  7. Jesus. So even when the universe itself decides we aren't allowed to live and tries to take away everything, we can make use out of something like this to live anyways.

    I suppose the only way to surely kill everything would be for another big bang to occur, of course we'll die but it will bring about the potential for new life at a later date.

    Ha, screw you universe!

  8. Wait couldn’t you have an infinite civilization made from the ashes of a black hole nuclear bomb genocide. Couldn’t it use the energy part to survive the war and go till literally the end of energy until a new galaxy???

  9. perhaps in just a few hundred more years human will think of much better way to harvest black hole energy instead of this inefficient superradiant method…

  10. A ring with the thickness of zero? Its much easier for me to imagine black holes don't exist. And wouldn't you know it? They don't.

  11. Good peaple: yay a power source from a black hole we do so many good things.

    Presidents: my nuke power is over 999999999!!!!!!

  12. Well imagine throwing this at someone and it explodes, well lets hope a very specific person that wants to nuke every country doesnt get its hands on it. Cough

  13. Step 1: achieve world peace and efficient world budget.

    Step 2. Terraform other planets.

    Step 3. Create a Dyson sphere around tye sun to sustaib those planets

    Step 4. Detect, sustain , and harvest wormwholes

    Step 5. Terraform the rest of the galaxy.

    Step 6. Create a Black hole bomb at the center. (Achieve galactic peace first!)

    Step 7. Live for millions of years.

    Step 8. Create mega black holes and harvest them.

    Step 9 . Live forever.

  14. Humans: put a mirror around it and hit it with electromagnetic beam

    Black hole: I don’t care about the physics I myself deny anymore

  15. Kurzgesagt : "We could use it as an endless source of energy for trillions of years"

    "Or we could blow it up"

    Me : I'm about to end my whole career

  16. Nothing gives me a good laugh like listening to this nonsense. " It spins so fast that it morphs space and time ". Yeah, sure. And to think it does it without puking too.

  17. We have not been to a black hole and we do not know how to do any of that until its done… this entire video is conjecture prove me wrong.

  18. 7:00 And in the last days, when the universe had gone dark and all of life was huddled around the last of the Ringularities, a unknown being fell asleep at the controls of the sphere. In a instant, the last flicker of existence was snuffed from the Universe. All that remains is a faint echo across the eternal void…

    "Doh!"

  19. Hey black holes have near limitless potential that you can use to watch more bird videos…

    Humanity: That'd be pretty good to make a real big explosion with, lets do that instead.

    Aliens at the end of time: Hey where is everyone else?

    They all made bombs out of black holes and nuked each other to death.

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