Comment by thehappypm
Comment by thehappypm 4 hours ago
I have a question about black holes, HN.
Let’s say you have a black hole. You fire a laser beam straight into it. Just by symmetry, shouldn’t it blueshift on the way in, gain some preposterous amount of energy — enough that it can escape?
> shouldn’t it blueshift on the way in, gain some preposterous amount of energy — enough that it can escape
You're devilishly close to the Penrose process by which "energy can be extracted from a rotating black hole" [1]. (You can also make them explode [2].)
[1] https://en.wikipedia.org/wiki/Penrose_process
[2] https://en.wikipedia.org/wiki/Black_hole_bomb