# Methods to turn a black hole into a energy source?
**URL:** https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356
**Category:** Factual Questions
**Created:** [September 9, 2009, 12:26am UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356 "2009-09-09T00:26:13Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)
#### Post date: [September 9, 2009, 12:26am UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/1 "2009-09-09T00:26:13Z")
I’m hoping for further information on this topic raised by Chronos [here](http://boards.straightdope.com/sdmb/showpost.php?p=11526543&postcount=4).
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### Author:  [@The\_Tao\_s\_Revenge](https://boards.straightdope.com/u/The_Tao_s_Revenge)
#### Post date: [September 9, 2009, 12:45am UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/2 "2009-09-09T00:45:34Z")
Also could this be a way to collect negative mass? Seems like if the black hole is eating virtual particles and emit Hawking radiation, then it should be a 50/50 shot whether it emits positive or negative mass.
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### Author:  [@badlyburnttoast](https://boards.straightdope.com/u/badlyburnttoast)
#### Post date: [September 9, 2009, 12:51am UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/3 "2009-09-09T00:51:51Z")
Assuming you can somehow contain it without it sinking out of reach into the center of the earth?
You could throw things (literally anything) into it and harness the hawking radiation that comes out. Free mass to energy conversion, hooray!
**The Tao’s Revenge** - it’s my understanding the negative energy particles always fall into the black hole, which makes everything balance out. I’m not a physicist or anything and, to be honest, I’m not sure I totally understand it so take that with a grain of salt.
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### Author:  [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)
#### Post date: [September 9, 2009, 1:06am UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/4 "2009-09-09T01:06:35Z")
I should have added at the end: So far as I’m aware, there’s never a free lunch in anything. Is there any reason to think that the power necessary to create a black hole would be small enough that you would able to get back more energy production within any sort of human time scale (within 100 years say)?
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### Author:  [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)
#### Post date: [September 9, 2009, 1:06am UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/5 "2009-09-09T01:06:56Z")
> [@badlyburnttoast](#):
>
> You could throw things (literally anything) into it and harness the hawking radiation that comes out. Free mass to energy conversion, hooray!
It’s not just Hawking radiation; stuff that gets squeezed as it gets sucked into the hole, stuff that orbits the hole at high speeds as it gets pulled in will put out lots of energy. That’s what you see when you see astronomical pictures of active black holes; Hawking radiation is so tiny with those massive holes that it barely exists. The spectacular effects are all due to the hole’s effect on matter as it falls in.
Basically, as you say if you want energy from a black hole you just have to toss stuff in.
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### Author:  [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)
#### Post date: [September 9, 2009, 1:09am UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/6 "2009-09-09T01:09:06Z")
> [@Sage\_Rat](#):
>
> I should have added at the end: So far as I’m aware, there’s never a free lunch in anything. Is there any reason to think that the power necessary to create a black hole would be small enough that you would able to get back more energy production within any sort of human time scale (within 100 years say)?
It would depend on the process used. But remember; a hole isn’t limited to the energy you put into it at its creation. You can keep feeding more matter to it and extracting energy from that matter indefinitely.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [September 9, 2009, 5:31pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/7 "2009-09-09T17:31:09Z")
There are three basic methods. First and most straightforward, there’s the gravitational potential energy. You can get usable energy out of things falling downhill. Well, a black hole is pretty much the ultimate downhill. This method can be used with any black hole whatsoever, and gives you energy equivalent to up to half of the amount of mass you toss in. This process is also what powers quasars, as **Der Trihs** mentioned.
Second, there’s Hawking radiation. It’s negligible for a large black hole (like, one formed from a star), but for a smaller hole (like one we might hope to form in a laboratory), it can be quite significant. Left to its own devices, a small black hole would evaporate away to nothing, but if you can continually feed it normal matter at the same rate that it’s radiating, you’ve effectively got 100% conversion of matter to energy. Unfortunately, a significant portion of the energy output would be in neutrinos, which we can’t harness, and you’d have to maintain a balancing act to feed the hole just the right amount: Get it too big, and it cools off and doesn’t produce as much radiation any more, and get it too small, and it’ll shrink away out of control and you lose your hole.
Finally, black holes can in principle be magnetic monopoles, and if we have the capability to make them from scratch in a particle accelerator, then we can probably make the monopole kind as well. According to the grand unified theories that combine the strong and electroweak forces, the proton is unstable, and eventually decays into lighter particles. Ordinarily, the proton’s lifetime is exceedingly long (far, far longer than the lifetime of the Universe), but in the presence of a magnetic monopole, the decay should occur much more rapidly. So putting a monopole (including a monopolar black hole) in with normal matter should cause the protons in the matter to decay, effectively converting matter to energy. This method would probably also waste some energy in neutrinos, though how much we can’t say yet without knowing the exact decay process. It might have a greater non-neutrino efficiency than the Hawking radiation process, and you don’t need to worry about ruining your engine: A magnetically-charged black hole would be absolutely stable, unless it meets another one of the opposite charge, so once you get the pair separated they’ll last forever.
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### Author:  [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)
#### Post date: [September 9, 2009, 6:02pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/8 "2009-09-09T18:02:10Z")
> [@The\_Tao\_s\_Revenge](#):
>
> Also could this be a way to collect negative mass? Seems like if the black hole is eating virtual particles and emit Hawking radiation, then it should be a 50/50 shot whether it emits positive or negative mass.
Nope.
The particle that falls into the Black Hole has to have negative energy. The rest of the Universe gets the now real particle.
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### Author:  [@SSgtBaloo](https://boards.straightdope.com/u/SSgtBaloo)
#### Post date: [September 9, 2009, 9:35pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/9 "2009-09-09T21:35:27Z")
Excerpted from the [Alpha Quadrant Institute of Technology](http://www.geocities.com/Area51/Shire/8641/index.htm) (my website, which I just learned is going to shut down when Yahoo deep-sixes Geocities – if you want to download anything from the site, now’s the time). While a work of fiction, I did look into the actual science and tried to be as correct as my feeble mind could muster. Note that references to “evaporation” of a black hole refer to the theory that a black hole loses mass over time due to (very slight) imbalances in the annihilation of virtual matter at the event horizon.
> [@](#):
>
> Fifth Report from the Vulcan Institute of Very Advanced Logic, Applied Science, and Various Endeavors of Generally Advanced Studies (VIVA LAS VEGAS)
>
> * * *
>
> It has come to our attention that many otherwise educated beings do not have a proper understanding of the technology used aboard starships. The following is intended to serve as a primer on the artificial singularity, known to be used as a power source by the Romulans.
>
> * * *
>
> **Typical primordial (quantum) singularity (QS) facts:**
>
> (The symbol in the angle brackets \<~\> is shorthand for “approximately”.)
>
> Event horizon diameter: about the size of a proton.
> Mass: 1 billion tons (equivalent to 1 cubic kilometer of water)
> Energy output from evaporation: ~6,000 megawatts (continuous)
> Approximate life span: ~10 billion years.
> Strength of gravity field:
> At 50 meters: ~1 gee
> At 1 meter: ~4,000 gees
>
> Energy released by final stages of evaporation resembles a massive explosion. Minimum energy released by this final decay is equivalent to a one million megaton nuclear blast (depends on the total types of particles which can exist). For comparison, Earth’s Sun releases this much energy in a tenth of a second.
>
> **Some thoughts:**
>
> Could a starship easily maneuver with an object (however small) that massed 1 billion tons (1,000,000,000,000 kg) aboard?
>
> How would you construct such an object and have it be “real”. By this, I mean, you would have to create a gravity field at least as intense as the smallest QS, and pump in about 1 billion tons of matter (it makes no difference what kind. It would be torn into atomic particles and photons before it reached the event horizon).
>
> Would you want something as dangerous as this to be permanent?
> We propose that there may be more than one way to create an artificial quantum singularity (the terminology used below was “coined” by our colleagues from Earth. We have agreed to use this terminology in honor of the human scholar who deduced a great deal of what we know about the workings uf the universe, Stephen Hawking).
>
> “Normal” AQS. This AQS is identical to a “real” QS, except it is created by artificial means. It has about 1 billion tons of mass and will be with us for a very, very long time. Don’t get in it’s way.
>
> AQS “light”: The AQS is created as above, but a smaller amount of matter is added to the singularity to make it “real”. When the sustaining fields are shut down, it evaporates within a few minutes (unless it ingests a huge amount of matter in the meantime) and releases as much energy as a real QS when it evaporates. (Vital statistics for this type of AQS are given below).
>
> Virtual AQS: The AQS is created by intense convergent subspace fields. Although it has no mass, it has a strong gravitic field and thus, “virtual mass”. It acts as a singularity as long as the fields remain in place, but “evaporates” with a much lower yield than a “real” QS when the fields are shut off.
>
> **Statistics for AQS “light”:**
>
> Event horizon diameter: somewhat smaller than a proton.
> Mass: 1 million tons (equivalent to the mass of a cube of water 100 meters on a side)
> Energy output from evaporation: more than ~6,000 gigawatts
> Approximate life span: (substantially) less than 10 billion years.
> Strength of gravity field:
>
> At 2 meters: ~1 gee
> At 1 meter: ~4 gees
>
> Advantages of AQS “light” over “normal” AQS: It won’t hang around for 10 billion years. You don’t have to pump it full of nearly as much “stuff” before you can use it. It releases more energy than the bigger one. Why? Because virtual particles forming near it have a better chance to escape, due to the lower mass and smaller surface area.
> Advantages of “virtual” AQS over other types: Possibility of adjusting field strength to match output to power requirements. Probably doesn’t make the ship disappear in an impressive radioactive fireball if something seriously goes wrong. You can turn it off if you want to (say, for maintenance). You can turn it back on when you want to (as long as there’s nothing wrong with the mechanism and you have power to “jump-start” it).
>
> How do you extract power from an AQS? There are at least three ways which require no technology more advanced than ours:
>
> If the AQS has spin, it will generate a rotating magnetic field. This rotating field will act as a rotor in a dynamo and will induce current in any wire placed in proximity to the AQS. It need not be very close, since a magnetic field is only slightly affected by the strong gravity field of the AQS. Induction coils can be integrated within the structure of the containment field generation equipment.
>
> Plasma can be produced by injecting matter at high velocity into the AQS chamber on a tangent to the event horizon (so it won’t vanish into the AQS’s event horizon). The distance from the singularity at which tidal forces turn matter into plasma is significantly greater than the radius of the event horizon. The plasma, already at a high velocity, may be removed with magnetic fields and run through a Magneto-Hydro-Dynamic (MHD) generator.
>
> The less massive a singularity is, the greater the amount of radiation it emits. Introduce a stream of matter well clear of the event horizon and the strong tidal zone and the radiation itself will heat the matter to a plasma state so it can be used in an MHD as in example 2.
>
> **How could an AQS be used as a weapon?**
>
> A “normal” AQS has a (relatively) large area of effect. Even if you grazed your target, it would suffer catastrophic effects. If it was detected before it came so close that the target vessel was unable to accelerate away from it, it might be severely damaged by tidal forces even if it did escape. If it was detected before it came too close, the target vessel might be able to muster enough gees of acceleration to get away. Whether you hit or you missed, you’d certainly have to remember where it went so you wouldn’t run into it later.
>
> The AQS “light” could be used in one of two ways. The first way would be to collide it with the target. Once it was in contact with the target, it would just “suck it up”, just like the heavier version. The other way would be to time things so that just as the AQS arrived at the target, it evaporated (with 1 million megatons’ worth of energy. Even the Borg don’t have shielding that good, one would imagine). A Borg cube masses well over one billion tons or more. It might be better to throw a barrage of AQSs at one with sufficient velocity so only a fraction of the total mass is carried off by any one AQS. This ensures that they will decay within a reasonable time.
>
> A “virtual” AQS would be used much like either of the above, but might be configured to collapse its sustaining fields before it ingested enough matter to form a permanent singularity. Actually, that would be very interesting. You’d have the initial effect of a regular QS, followed by the same sort of energy released by a real QS because it would have ingested enough mass before the sustainer field collapsed to be a real QS.
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### Author:  [@BrandonR](https://boards.straightdope.com/u/BrandonR)
#### Post date: [September 9, 2009, 9:39pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/10 "2009-09-09T21:39:49Z")
Couldn’t we just make a ridiculously long cable, wind it up on a drum connected to a generator, connect the end of the cable to a mass and throw it in the black hole? Obviously I know the logistics seem a bit off but at least it seems theoretically feasible…
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### Author:  [@ivn1188](https://boards.straightdope.com/u/ivn1188)
#### Post date: [September 9, 2009, 9:57pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/11 "2009-09-09T21:57:55Z")
You can also take a spinning kerr-newman black hole and kick some particles through the ergosphere of the hole, and then part of them will come out with more energy than the mass+energy put in.
It’s called the Penrose process. Basically, think of the hole as a giant flywheel (most black holes should be spinning) – you can add or subtract angular momentum from the hole.
As far as using black holes as energy sources, this should be the most efficient method if it works.
[http://www.indopedia.org/Kerr-Newman\_black\_hole.html](http://www.indopedia.org/Kerr-Newman_black_hole.html)
[http://en.wikipedia.org/wiki/Penrose\_process](http://en.wikipedia.org/wiki/Penrose_process)
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### Author:  [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)
#### Post date: [September 9, 2009, 10:20pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/12 "2009-09-09T22:20:43Z")
> [@BrandonR](#):
>
> Couldn’t we just make a ridiculously long cable, wind it up on a drum connected to a generator, connect the end of the cable to a mass and throw it in the black hole? Obviously I know the logistics seem a bit off but at least it seems theoretically feasible…
Not sure why you’d even need a black hole for this.
Jupiter has a pretty impressive magnetic field.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [September 9, 2009, 11:54pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/13 "2009-09-09T23:54:15Z")
What’s Jupiter’s magnetic field have to do with anything? What **BrandonR** is proposing is one possible way to use the gravitational potential energy method. I’m no engineer, so I can’t say if that would be the most practical way to do it, but sure, it would work.
And the Penrose process can only extract that portion of the energy which is stored in the hole’s rotation. Eventually, once you’ve extracted all of the rotational energy the hole started with, you’ve got a non-spinning black hole that can no longer be used for the Penrose process, and no cheap way to spin it back up again. Basically, you’re using the black hole itself as a fuel, rather than the hole enabling you to use some other sort of matter as fuel.
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### Author:  [@ivn1188](https://boards.straightdope.com/u/ivn1188)
#### Post date: [September 10, 2009, 12:14am UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/14 "2009-09-10T00:14:19Z")
> [@Chronos](#):
>
> And the Penrose process can only extract that portion of the energy which is stored in the hole’s rotation. Eventually, once you’ve extracted all of the rotational energy the hole started with, you’ve got a non-spinning black hole that can no longer be used for the Penrose process, and no cheap way to spin it back up again. Basically, you’re using the black hole itself as a fuel, rather than the hole enabling you to use some other sort of matter as fuel.
Yes, well, harnessing the freely available angular momentum of a super-stellar sized mass seems a lot more effective, cheap, and efficient way of collecting usable energy than just tossing stuff in like its a campfire, and seems to meet the OP’s lack of criteria just fine.
And hey, when you finally have a schwarschild black hole, _then_ you can just throw things in it if you want.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [September 10, 2009, 1:11am UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/15 "2009-09-10T01:11:25Z")
I guess that depends on whether we get the technology for cheap, deep interstellar travel first, or the technology for laboratory-scale manufactured black holes.
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### Author:  [@tim314](https://boards.straightdope.com/u/tim314)
#### Post date: [September 10, 2009, 7:39am UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/16 "2009-09-10T07:39:40Z")
> [@Chronos](#):
>
> What’s Jupiter’s magnetic field have to do with anything? What **BrandonR** is proposing is one possible way to use the gravitational potential energy method. I’m no engineer, so I can’t say if that would be the most practical way to do it, but sure, it would work.
I’m guessing maybe **Whack-a-Mole** meant to refer to Jupiter’s _gravitational_ field.
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### Author:  [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)
#### Post date: [September 10, 2009, 3:27pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/17 "2009-09-10T15:27:53Z")
> [@tim314](#):
>
> I’m guessing maybe **Whack-a-Mole** meant to refer to Jupiter’s _gravitational_ field.
Err…yeah. :smack:
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [September 10, 2009, 7:34pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/18 "2009-09-10T19:34:58Z")
Eh, Jupiter’s gravity well isn’t all that useful, since to get down into Jupiter’s well, you first have to get up out of Earth’s well, as well as further up away from the Sun. The surface of the Earth is probably at a lower total gravitational potential than Jupiter. But in any event, none of them are at all even remotely significant compared to the gravity well of a black hole.
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### Author:  [@ivn1188](https://boards.straightdope.com/u/ivn1188)
#### Post date: [September 10, 2009, 8:41pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/19 "2009-09-10T20:41:53Z")
A “laboratory sized” black hole will not have significant gravity above the nano-scale event horizon. How would this provide energy?
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### Author:  [@tim314](https://boards.straightdope.com/u/tim314)
#### Post date: [September 10, 2009, 9:05pm UTC](https://boards.straightdope.com/t/methods-to-turn-a-black-hole-into-a-energy-source/509356/20 "2009-09-10T21:05:47Z")
> [@Chronos](#):
>
> According to the grand unified theories that combine the strong and electroweak forces, the proton is unstable, and eventually decays into lighter particles. Ordinarily, the proton’s lifetime is exceedingly long (far, far longer than the lifetime of the Universe), but in the presence of a magnetic monopole, the decay should occur much more rapidly.
Is this monopole-induced proton decay a generic feature of all GUTs? Or would it depend on how the forces are unified?
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