dreamer_easy | Entries tagged with black hole eh

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I've been reading a lot about black holes recently. Fact: you can use a rotating black hole as a power source (there are various ways to accomplish this). Perhaps in the far-flung future our descendants will be powering their civilisations with black holes. Anyway, I was just now reading about flywheels, which you can use to store and retrieve energy, and I realised this was exactly the same physics (pretty much) as the rotating black holes. Conservation of angular momentum, large and small.

I profoundly regret not studying physics in high school, which means as an SF reader and writer I constantly struggle with concepts I barely grasp. So this was a pretty exciting moment. Now to Khan Academy for some lessons.

"According to general relativity, the inward gravitational collapse never stops. Even though, from the outside, the black hole appears to stay a constant size, expanding slightly only when new things fall into it, its interior volume grows bigger and bigger all the time as space stretches toward the center point. For a simplified picture of this eternal growth, imagine a black hole as a funnel extending downward from a two-dimensional sheet representing the fabric of space-time. The funnel gets deeper and deeper, so that infalling things never quite reach the mysterious singularity at the bottom. In reality, a black hole is a funnel that stretches inward from all three spatial directions. A spherical boundary surrounds it called the “event horizon,” marking the point of no return." -- What Keeps Black Holes From Expanding Everywhere? (The Atlantic, 10 December 2018)

Great horny toads!

(Cf the behaviour of space-time in the Big Rip, and the volume of negatively curved space.)