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.

source