Minutephysics compares how efficiently different processes convert mass to energy per E=mc^2, from fire and fission to fusion, antimatter and black holes, which can convert a large fraction of mass to energy.
Why Hacker News points people here: Linked as a quick, clear primer when black hole energy and efficiency come up.
Quick info on Kugelblitzes and getting energy from black holes
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I don’t see why it’s unbelievable. High mass energy conversion is one of the least crazy things about black holes imo. For readers who want some quick info: this video This PBS SpaceTime video doesn’t talk about the practical uses of Kugelblitzes, but it isn’t a big leap from understanding what they are to how to get energy out of them. Hawking radiation rate increases as schwarzschild radius decreases. If you could make a properly sized black hole you could convert a little bit of mass into a lot of energy. Maybe this could be harnessed to solve all electricity demand issues. Maybe it could be used to make a room sized bomb that blows up Earth. Vote now on your phones. link
RecommendsjerfOct 2021
“You may also enjoy: which is a minutephysics on black hole power”
Black hole power using similar principles at higher efficiency
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Well, that very nearly is the method of power generation. It would presumably be paired with some sort of Dyson sphere around the white dwarf. (Remember that a "Dyson sphere" isn't necessarily a solid shell, but just some configuration of matter where no matter which direction the energy goes it is intercepted by something.) You may also enjoy: this video which is a minutephysics on black hole power using much the same principles but attaining yet higher efficiencies.
Cites itpantalaimonJul 2025
“They actually convert up to 42% of their mass into energy, mostly radiation”
Black holes convert up to 42% of mass into energy
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> minus a few percent to gravitational waves They actually convert up to 42% of their mass into energy, mostly radiation this video
