28 | Roger Penrose on Spacetime, Consciousness, and the Universe
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
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The Differential Topology of Gravity
Gravitation acts like an astigmatic lens. If you just go through empty space, then it focuses one way and expands out in the other direction. This is what leads to spaghettification if you fall into a black hole. So I knew about these things by thinking about these focusing effects and so on. And it was using this kind of argument together with topological arguments that you could see if you reached a point of no return and that was a critical point which would make gravitational waves irreversible. Really it gets to a point where you don't know what happens, it sort of stops, space time gives up.
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