A Dyson sphere around a black hole

Better link: https://arxiv.org/abs/2106.15181

The results are fairly obvious: CMB and Hawking radiation provide almost zero power output, while an accretion disk and relativistic jets can provide a lot of power.

Oh cool, CC-BY!

In theory you can get an arbitrary amount of power from Hawking radiation if you have a lot of very small black holes instead of just one big one. I feel like the stability of the negative-feedback control systems for their orbits might be important here, especially if they're orbiting something you care about like your home planet.

As far as I understand, small black holes could be used as a super efficient energy storage („Kugelblitz“), but hardly as a source, assuming that primordial black holes are rare. Primordial black holes afaik are the only theorized origin of a sub stellar mass black hole at this stage of the universe‘s timeline.

If only there was a way to break up the smallest size of black holes (there isn’t). If it was split up into several or thousands of much smaller black holes they, being much smaller would give off energy faster.

Energy is energy wouldn’t a matter black hole and an anti matter black hole just make a black twice the size, minus a bit for gravity waves.

I was thinking given a large enough gravity wave it might be able to stretch a black hole apart. How huge that could be, and how that could be generated is probably beyond the limits of reality.

Oh, you wouldn't want to be able to split up black holes, since that means they could be destroyed during warfare.

Depending on what the cosmological constant is, massive black holes could be quite useful in the far future. 10^100 years from now, long after all the stars have gone out, it could be the case that the only life in the universe would be huddled up against the event horizon of supermassive black holes, exploiting the tiny temperature difference between the pseudosurface and the void to generate a trickle of power.

Splitting black holes would rob the far future of that power source to be used now. You could do it, but why shorten the useful life of the universe?