Interview, Fireside Chat
Why Space Elevators Can't Mine Black Holes – Adam Brown
- Black holes are projected as a potential final energy source for distant descendants only after all stellar and other energy reserves are exhausted, with a solar-mass black hole naturally releasing its energy via Hawking radiation over a timescale of roughly 10^55 times the current age of the universe.
- Mechanical proposals to accelerate extraction by dragging Hawking radiation from near the event horizon face severe material constraints and are deemed unlikely to meet current or near-future energy needs due to the slow pace of the process.
- While carbon nanotubes could theoretically enable an Earth-based space elevator within the next century if produced with sufficient length, purity, and strength, they are entirely inadequate for black hole mining because their tensile strength-to-mass ratio of approximately 10^-12 falls short of requirements.
- Physical laws impose a fundamental upper bound on the tensile strength-to-mass ratio of any rope, which hypothetical fundamental strings from string theory might just saturate, though such a limit would leave no residual strength capacity to support a payload.
- Rapid black hole mining is ultimately doomed by the necessity of ropes with maximum theoretical strength, as any material reaching this limit would lack the capacity to transport energy or payloads.
- Conventional nuclear processes offer a maximum energy yield of one part in 1,000 to 10,000 of the starting material's rest mass, leaving approximately 99.9% of the energy in protons and neutrons inaccessible due to baryon number conservation.
- Future technological utility for black holes may depend on creating small black holes and feeding them protons and neutrons to convert them into photons, gravitons, and neutrinos.
- Power plants utilizing this mechanism are theoretically capable of 100% efficiency by capturing all emitted radiation to convert the entire rest mass ($mc^2$) of input matter into energy.