How would one destroy a black hole?

Question

Science-Fiction has tools to destroy anything: atoms, molecules, DNA, cellular organisms, multicellular organisms, buildings, streets, cities, countries, continents, planets, and even stars. Some extreme settings even have tools to destroy entire galaxies, and I know of at least one setting (Doctor Who) where they can destroy a whole universe and even the multiverse.

However, as far as I know, no scientist or writer has come up with a way to destroy a black hole. I'm not just talking about "wait for it to decay through Hawking Radiation"; I'm talking about "use this and the black hole just disappears in a reasonable timeframe.

Would such a method even exist? It can require unobtanium, obviously.

Answer 1

Welcome to How to destroy a black hole for dummies

So, are you looking for a way to eliminate the right black hole, arent' you? Well, you're reading the right guide. But before beginning, it could be useful to make some clarifications on the nature of these galactic monsters. As Sun Tzu says, to defeat your enemy, you must first know him. Let's know what a black hole is.

1) Why black holes are a so formidable opponent?

Black holes are the natural enemies of all spacefaring races. With their bottomless capacity to consume all light and matter, it’s just a few septillion years before all things in the Universe have found their way into the cavernous maw of a black hole, crushed into the infinitely dense singularity. For a black hole, any matter entering the event horizon is added to the mass. Shoot bullets at a black hole, and you just make a slightly more massive, slightly more dangerous black hole. Detonate a nuclear bomb inside the event horizon, and you only make the black hole more massive. Fire your forward phasers at the black hole, and that’ll still make it even more massive. Swap those bullets in for lasers and black holes don’t care. Within the event horizon, energy and matter are one, and those very same black holes can convert that energy into mass. So all your projectiles and energy weapons inevitably just make it more dangerous. So the problem is that any material is introduced into a black hole (whatever is physical matter or energy) will be swallowed up and will contribute to the growth of the enemy.

What if I use an anti-matter weapon? Maybe throwing an antimatter black hole into a black hole? We'll have a nice KABOOM, and problem solved

Nice try Jimmy. The problem is that even if you manage to create and stabilize an anti-matter black hole (and it is doubly impossible, because first you have to find a way to contain antimatter, and then you have to find a way to contain an antimatter...black hole), throwing it at a black hole will surely create a huuuge explosion, but all the energy will be converted and processed by the black hole. The bottom line is: if a regular black hole and an antimatter black hole got black-hole-married in space, they wouldn’t vanish.

2) Solutions

So, what are the possibile solutions to destroy a black hole? The answer, surprisingly, lies in the enemy's very features. We must take advantage of the enemy's ability and twist them against it.

Wait

Yess...just wait. I know, it's the most boring one, but at least it's a solution. According to Stephen Hawking, black holes can actually evaporate over enormous periods of time. So, over an incomprehensible period of time, even the most supermassive of the black holes will have evaporated away into a harmless soup of particles. It turns out, in order to defeat the black hole menace, all we need to do is ignore them, and they’ll go away all on their own. But, if you asked how to destroy a black hole, I suppose you need it now. So, next solution is to...

Get rid of event horizon

Getting rid the events get two interesting results; first of all, you get what you want: you killed a black hole. In addition, once removed the horizon, you will have access to real black hole, and all its secrets. The problem is this solution is a bit complicated.

In general relativity, the mathematical condition for the existence of a black hole with an event horizon is simple. It is given by the following inequality: $$ M^2 > \left(\frac{J}{M}\right)^2 + Q^2 $$ where $M$ is the mass of the black hole, $J$ is its angular momentum and $Q$ is its charge.

Getting rid of the event horizon is simply a question of increasing the angular momentum and/or charge of this object until the inequality is reversed. When that happens the event horizon disappears and the exotic object beneath emerges. But that hides a multitude of problems. For a start, things with angular momentum and charge also tend to have mass. And in any case, the equation above describes a steady state. Feeding a black hole creates a dynamic state and there is no guarantee that the object will settle back into a steady state again without shedding the angular momentum and charge that it has been fed. In fact, the calculations are so fiendish that they have defied all attempts to tame them.

Use time travel device

Remember when we said that blacks holes in time dissolve? Sure, it takes eons, but what if you could speed up the time? Creates a kind of space-time bubble, and speeds up the time. The black hole will dissolve as expected, or perhaps even more quickly, failing its nourishment.

Answer 2

Use Negative Energy/Negative Mass.

To visualize this concept, consider the rubber sheet model of gravity:

1. Spacetime is modeled as a taut rubber sheet.
2. Masses placed on the sheet cause a distortion in the sheet, causing nearby objects to fall towards each other (this models gravity).

Now, suppose we have an object of negative mass. Instead of pushing down on the sheet, it will pull up. This will cause positive-energy objects to move away from it, and other negative-energy objects to move towards it.

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If we collide this negative-energy object with the black hole, its mass will be reduced by an amount equivalent in magnitude to the energy of the negative-energy object.

Note that this is all strictly theoretical, and the existence of macroscopic negative-energy particles has not been proven.

However, the physics behind this is very similar to Hawking radiation, which involves negative energy regions on the quantum scale.

Also note that negative energy matter is very different from antimatter, which has been proven to exist and has positive energy.

Answer 3

The only way a black hole will ever disappear, as far as we know, is through Hawking radiation. Think of a black hole as a ball of energy. You don't destroy energy, we know that well, you just do stuff to it. Well, you can't do anything to a black hole, so regardless of what you throw at it, nukes, lasers, stars, etc., you will just add more energy to it.

If you have control of time, you could encapsulate the black hole in a localized time distortion in which time is accelerated, so that the black hole evaporates faster.

You could try and create your own anti blackhole with antimatter and collide the two, but we don't really know what happens to matter in a black hole, so you might just end up creating a normal black hole.

Answer 4

The problem is that once anything has crossed the event horizon it needs to be travelling faster than light to come back out - which is impossible with any known science.

So you either need to accelerate the mass to FTL speeds or reduce the curvature of space-time so that mass can escape.

However you do this I'm viewing it as being like puncturing a balloon, you create a breach in the event horizon and let the mass from the black hole pour out through it. The mass would jet away into space gradually reducing the size of the black hole until it is all out.

The breach can be explained using either of the mechanics I explain above - either you're forming a wormhole or in some other way accelerating the matter to FTL speeds or you're reducing the gravitational effect in a region so it's no longer a singularity at that point.

Doing this would require a LOT of energy, you need to overcome the gravitational force of the black hole to suck the matter inside it out or you're going to be violating several laws of thermodynamics.

Answer 5

Can you convert a black hole into gravitational radiation?

The recently observed merger of two black holes converted three solar masses of black hole, or about 5% of the total mass. So what if you could place a massive object in close orbit around a black hole and feed energy into it to prevent it spiralling in to the black hole? That is a continuous gravitational wave source. The question I don't know the answer to, is whether it will be emitting more in gravitational radiation, than is being supplied to prevent inspiralling. If more, the black hole's mass is being converted to energy. If less, you have just found an exotic and inefficient way to make the black hole grow.

One for the physicists, I think!

Answer 6

The answer is to manipulate Hawking radiation. It is thought that "virtual particles" pop in and out of existence all the time in our universe, but generally they are anti particles of each other and instantaneously collide, and return to the vacuum (big handwaving paraphrase here to introduce the topic).

Near the event horizon of a black hole, the virtual pair can appear, but there is a chance that one of the particles is absorbed by the black hole while the other is ejected into the "real" universe. The black hole loses the mass and energy of the ejected particle, which is registered in the universe as Hawking radiation.

Since we want to make the black hole disappear, we need to induce Hawking radiation to flow out of the black hole at a much faster rate than normal. By much faster we mean orders of magnitude, since a solar sized black hole could take 2×10⁶⁷ years to evaporate under natural circumstances.

Virtual particles appearing near a black hole's event horizon will need to be accelerated away from the hole in order to drain its mass. One possible way to do this would be to position something like a neutron star in close orbit around the black hole, just skimming over the event horizon. The powerful gravitational pull of the neutron star will rapidly accelerate any virtual particles away from the hole itself, and create a sort of "anti accretion" disc of now real particles streaming away from the hole in the wake of the neutron star.

The other thing for this to work is to ensure that there is little or no matter and energy in falling into the black hole. The neutron star could be used to transfer momentum of the material in the accretion disc away from the black hole during the period it is being manoeuvred into position, clearing the disc and preparing for the phase where it is "vacuuming" virtual particles away from the event horizon.

One could enhance the project by employing multiple neutron stars in tight orbits to strip away the accretion disc and channel virtual particles away from the event horizon. The amount of super science and technology needed to do this would be pretty mind boggling, though.

Answer 7

NovaLogic already got the right idea: The only known way to diminish a black hole is by using the Hawking radiation. But he did not given an implementation of an exploit. Here is mine:

The inverse Dyson sphere

You construct a Dyson sphere well out of the reach of the black hole's horizon. Than you cool down the inside of the Dyson sphere to be colder than the temperature of the enclosed black hole. At this moment, you start reducing the black hole by catching Hawking radiation from it and pumping it outwards.

Note that this method will be incredibly slow and it needs a lot of energy, too. But in the end, your black hole is destroyed.

P.S. In an always expanding universe, the cosmis background will become colder and colder, and all black holes will naturally die of this cause.

Answer 8

Doesn't sound too difficult.

You need:
- Unobtanium hull (handwavium is also good)
- FTL drive (not the old-fashioned types that don't work in a gravity well, but a modern one)
- Suicide crew (or AI without self-protection circuits)

Enter the event horizon (the hull protects you from tidal stresses); approach the singularity and turn on the FTL drive. The ship and the singularity (where all the mass is) take off to the programmed destination.

You can't pass the event horizon without exceeding the speed of light, so we do just that. We program the FTL to rematerialize outside the Milky way, since what will arrive there is a naked singularity. This will cause all sorts of problems for the crew, but it will take thousands of years before they affect us. That'll be somebody else's problem.

Answer 9

Temporarily suspend local gravity.

A black hole is a gravity bound, infinitely dense ball of matter. It holds together because the force of gravity is sufficient to overcome the forces pushing it apart.

If one had the ability to manipulate gravity, perhaps one has antigravity spaceships, one might potentially temporarily shut down gravity in a local region of space for a tiny fraction of a second.

I have no mechanism for how this might be achieved. This falls outside of any current physics.

This would make a very considerable bang

It would be worth noting that this would likely create quite a big bang, probably on the order of a supernova. Large enough to destroy any nearby star system. Probably large enough to cook any planets within a few light years of the event.

Answer 10

Peer Pressure.

I fully expect someone to explain why this won't work (I'm guessing it'll be the divide-by-distance-squared part of the gravitational force equation), and that would be just fine.

But let's give it a shot.

1) Find a black hole that's only about 20 solar masses. This isn't a general solution, maybe after we pick off a few of the weak ones we can aspire to more.

2) Find several stars that are about 5-10 solar masses each.

3) Using your unobtanium power sources and some bored engineers, maneuver those stars into a globe centered around the black hole.

4) Carefully and synchronously move the stars closer to the black hole, not letting any of them get sucked in, until the stars are exerting more force on the matter inside the event horizon than the singularity itself.

5) If the matter won't come out yet (due to being pulled equally in all directions), shift stars around until enough net force is exerted in a given direction from the center of the black hole that matter previously inside its event horizon starts to move away from it again.

6) Figure out what to do with 4*10^31 kilograms of post-stellar matter.

Answer 11

I think antigravity would be the "simple" approach using common sci-fi devices. Hypothetically, we could have gravitons and anti-gravitons of some kind where the one cancels out the other. Then we just stream ridiculous amounts of antigravity towards the gravity, and eventually the black hole falls apart.

This presumes that A) your scientists find a way to create artificial gravity, and B) that negative gravity exists. And C) that you have a bunch of stars lying around with Dyson spheres you can use to power your antigravity beams.

Answer 12

So. Black holes are hard to approach. Time gets a little, shall we say, funky as you get closer. And then, of course, there's the tide. They'll tear a ship apart quicker than anything. I won't even give more than a cursory nod to the radiation, as we're all familiar with that. So, obviously, dropping some sort of magic bomb into the black hole won't work.

So, instead of trying to bring something to the black hole, we do the opposite. We bring the black hole to us.

Now, now, I know what you're saying. You don't move a black hole. And you're right. But think - We can create wormholes, right? We've been using them to get from place to place for a century now.

Only one problem. The wormholes only work one way. Generate one, put something in it, and it pops out the other end. What if I told you we found a way to reverse that? The generator, instead of creating the entrance, creates the exit? We've found a way - And while the maths of it are beyond me, Doctor Selene here will be more than happy to explain when I'm done.

So, we set up a generator and target it below the black hole's surface. The wormhole opens, and the black hole's own gravity pushes mass through. But, very quickly, that mass will be the entire black hole. At that point, we've only managed to move the black hole, and right on top of ourselves. Bad, right?

The solution is fairly obvious. Using a network of a few, let's say four, dozen generators spread across just as many systems, we use a quantum clock to synchronize them. They all open their wormholes at the same time, siphon off some of the black hole's mass, and close the wormholes before too much comes through. At that point, we have loads of what Doctor Selene calls exotic materials floating around ready to be harvested. Scoop them up, put them on some novelty keychains, and sell them in a gift shop, right? Oh, yes, the scientists will get their turn too.

It'd take a few cycles of this to completely remove the black hole, maybe a few months, but think of the rewards! Beta Three-Thirteen is sitting right in the middle of what would be a prime route between Caldari and Melantis. We'd see huge amounts of traffic between the two systems if we got rid of it! And I'm told the materials we'd be able to gain from the hole would be usable in dozens of industries!

We can do this, and we will do this. Now, I'll leave you Doctor Selene to answer the more technical questions.

Answer 13

reduce the pressure with a tiny portal/teleporter

Teleporters or portal technology is pretty common in sf. You just use some additional dimensions to "fold" space (like I explained here) and punch a hole through space into the black hole.

You have to be careful though:
1. Only make a very tiny hole! If to much mass comes through that hole at once, it will just create a second black hole at the other end of the portal.
2. Aim the output-hole at empty space or something you want to destroy. You will get a constant stream of mass at a very high speed coming through.

But you also have some really neat side-effects:
1. You can power a big generator with the kinetic energy from that stream.
2. After you draw most of the kinetic energy from that stream, you can use the huge amount of mass to build a complete new stellar system or two.
3. You can fire the full power of that stream on an enemy battle fleet/base/planet
4. You can fire that stream roughly in the direction where you want to build that intergalactic highway, thus blowing away all that debris (planets, suns and stuff) to clear the way.

If that is to slow for you, you can use several tiny portals and direct the stream in different directions.
After a while, the mass of the black hole will have reduced enough, that it is just a big sun and the stream(s) will be reduced to a trickle of plasma from that sun. Now you can use your standard death star to blow it up and have some neat empty space.

Answer 14

You find the spot in a parallel dimension that is closest to the location of the singularity in the black hole. You then poke a hole between the dimensions so that some of the singularity can spill over into the other side.

The mechanics are left as an exercise for the student.