4 ms·
That's a classical cartoon sketch of a black hole, it's not how they work in relativity. Black holes (specifically event horizons) are phenomena of space-time.
by InclinedPlane 9y ago
That's a classical cartoon sketch of a black hole, it's not how they work in relativity. Black holes (specifically event horizons) are phenomena of space-time. They are regions where space-time is distorted in a way that leads to no space-time trajectories that leave the event horizon (in fact, all space-time trajectories that start within an event horizon inevitably have futures which go into the singularity). They incidentally trap light, but it's more accurate to say that they trap the future.
- dotancohen 9y ago> They incidentally trap light, but it's more accurate to say that they trap the future. That's an extraordinarily poetic way to put it, and not wrong. But I'd say that the black hole doesn't trap exactly the future, but rather prevents it from occurring. Due to time dilation the theoretical observer falling into the hole observes nothing special at event horizon and indeed time slows and asymptotically stops. That observer is forever falling, forever seeing out, slower and slower.
- TeMPOraL 9y agoMakes me wonder. Could you have a hollow black hole? I.e. some kind of large, spherical boundary for "all space-time trajectories", but left some space(time) in the interior free of large gravitational gradients - a space where stuff could live "normal time", forever isolated from the rest of the universe.
- ianai 9y agoBut where then does the gravity come from the BH? If all forces are transmitted by particles, where do the gravitons come from to pull things into the BH?