cross-posted from: https://lemm.ee/post/64402838
TLDR:
Theoretical and experimental evidence now strongly supports the possibility of energy extraction from spinning objects, including black holes.
Creating a “black hole bomb” is no longer just science fiction—lab-scale analogs exist.
Realizing a full-scale version (especially around a real black hole) is still far in the future, but the groundwork is being laid.
Main Idea
It is theoretically and experimentally possible to extract energy from spinning black holes, and under specific conditions, this could be amplified to create what’s known as a “black hole bomb.”
Theoretical Background
Penrose Process (1969)
Proposed by Roger Penrose.
Energy can be extracted from a spinning black hole via its ergosphere.
The ergosphere is a region just outside the event horizon where spacetime is dragged due to the black hole’s spin.
Inside this region:
- Objects cannot remain stationary.
- Energy can be gained if mass is ejected in the right way.
- A spacecraft, for instance, could enter the ergosphere and leave with more energy than it had.
Zeldovich Effect (1971)
- Proposed by Yakov Zeldovich.
- Rotating bodies (not just black holes) can amplify electromagnetic waves via rotational energy.
- Predicted that light or sound aimed at a spinning object could gain energy upon reflection.
- Required extremely high rotational speeds—nearly relativistic—for noticeable effects.
Experimental Verification
Sound Waves (2020)
- Spinning absorptive disc increased the energy of low-frequency sound waves.
- Proved the Zeldovich effect using acoustics.
Electromagnetic Waves (2023–2024)
- A spinning aluminum cylinder with surrounding magnetic coils showed energy amplification of EM waves.
- Rotation direction affected energy gain/loss.
- First real-world proof of the superradiance concept from Zeldovich’s theory.
Black Hole Bomb Concept (1972)
Key Mechanism
Enclose a spinning black hole (or any rotating energy source) with a reflective mirror.
Waves bounce between the mirror and ergosphere, each time gaining energy from the black hole’s spin.
This creates a positive feedback loop:
- Energy builds exponentially.
- Could result in an enormous explosion (i.e., a “black hole bomb”).
- Or energy could be released in a controlled burst, like a black hole plasma gun.
Recent Experiments (2024)
Miniature black hole bomb analog was created:
- A metal cylinder was rotated.
- Surrounded by coils acting as magnetic mirrors.
- EM waves were amplified exponentially when rotation threshold was met.
- Verified theoretical predictions experimentally for the first time.
Challenges & Future Research
For Actual Black Holes
- Creating a real reflective mirror around a black hole is still theoretical.
- Stabilizing such a structure near a black hole is currently beyond our technology.
Next Step: Quantum Foam
Researchers aim to attempt amplification using quantum vacuum energy (quantum foam).
If successful:
- Could demonstrate energy extraction from spacetime itself.
- Would confirm another Zeldovich prediction.
- Potential Nobel Prize-level breakthrough.
Whoa! You can get energy from gravity and spin?? Who would have guessed
The thing missing from most of these bullet points is that extracting energy from rotation reduces the speed of the rotating object.
Even black holes are affected by the gravity of objects near them, same as anything else - which means that the black hole will slow down if you slingshot an object around it.
That’s why it’s called energy extraction rather than energy creation.
So sure, you could make a black hole bomb… but making the black hole in the first place would take as much - if not more - energy than you’ll get out of it. And usually you’re going to do enough damage just throwing a black hole through your target.
But a black hole bomb is the only way to be sure
Oh thank God, a black hole bomb.
I was worried we hit our limit for our potential to completely destroy the planet.
So this all seems to hinge on the creation of black holes. Last I checked we can’t do that, right?
In familiar three-dimensional gravity, the minimum energy of a microscopic black hole is 1016 TeV (equivalent to 1.6 GJ or 444 kWh), which would have to be condensed into a region on the order of the Planck length. This is far beyond the limits of any current technology. It is estimated that to collide two particles to within a distance of a Planck length with currently achievable magnetic field strengths would require a ring accelerator about 1,000 light years in diameter to keep the particles on track.[citation needed]
From: https://en.m.wikipedia.org/wiki/Micro_black_hole
So it’s quite unfeasible and energy consuming. To say the least.
Why not simply use an antimatter bomb? Wouldn’t that have way more explosive power?
Where are you getting the antimatter from? You need to eat a lot of bananas to get enough for a sizeable explosion.
I honestly think it is more realistic for humanity to use a black hole as energy source than using antimatter.
Yeah, and where do you get a black hole that happens to have the appropriate size?
We already know of some. We “just” have to get there.
Yeah sure. We just have to build a spaceship, travel a few thousand lightyears, then accelerate the black hole into the desired direction, probably with an amount if energy that also requires us to build a dyson sphere around the next star. Then wait some ten thousands of years, decelerate it, build the energy harvesting mechanism around it, and boom, enemy obliterated.
I really feel it could be more efficient to just make some antimatter out of pure energy, here on earth, and just mail it to them in a letter bomb.
I mean producing antimatter is ridiculous, too. But so is obtaining a black hole. And I don’t get why you wouldn’t then directly use it as is, or use the energy you wasted on the project directly. But instead harvest a tiny amount of a black hole’s energy to convert specifically that into a weapon… And what kind of application needs “bombs” which are fine to arrive in a few hundred thousands of years or so?
I honestly totally blanked out the “bomb” part in my head. You’re right.
It’s probably also easier to harness the black hole’s energy to produce anti matter and mail it to the aliens than it is to use the hole directly.
Or build a death star. I suppose that skips one conversion step, sucks energy from something and blasts this directly as energy in a death ray. I guess that would do for most cases a bomb works. (And it’s kind of similar to the idea here, minus the black hole and spin energy.)
Some people can get energy from their hole directly.
Could demonstrate energy extraction from **spacetime itself
Please, don’t tell the capitalists.
How much time would a black hole bomb take to go off?
In the lore for the game VALORANT they use these to steal radianite from parallel universes
