The Unreasonable Efficiency of Black Holes

minutephysics2 HN recommenders · 2020–2025
4.5M views · explainer · evergreen · Uploaded 2017-12-31

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.

Linked as a quick, clear primer when black hole energy and efficiency come up.

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3 comments from Hacker News

@willis9362020 · in “Black hole paradoxes reveal a fundamental link between energy and order”

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: [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]

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@jerf2021 · in “We've spotted a planet surviving its dying star”

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: [VIDEO] which is a minutephysics on black hole power using much the same principles but attaining yet higher efficiencies.

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@pantalaimon2025 · in “LIGO detects most massive black hole merger to date”

> minus a few percent to gravitational waves They actually convert up to 42% of their mass into energy, mostly radiation [VIDEO]