Oh I see what you're saying. Spoiler: If someone falls into a black hole they die horribly.
Not if the black hole is big enough, but large enough black holes might not
exist, so for all practical purposes you're probably correct.
iirc I read something a while ago about how it depends on whose perspective you look at. From the perspective of viewing someone falling into a black hole, they approach the event horizon and never actually reach it. Assuming that they aren't horribly killed quickly by the disc of high-velocity plasma around the black hole, you'll see them very slowly approach a horrible death.
From the perspective of someone falling into a black hole, they go past the event horizon just fine and then die horribly once the tidal forces are too strong for their body to stay together.
That sounds about right - assuming that the tidal forces don't kill you before you reach the event horizon.
But the interesting thing is that according to some interpretations different things happen in different perspectives but they both happen.
...that sounds like the
ladder paradox, at least superficially.
PPE: What would falling into a black hole look like, though? Wouldn't the universe around you get brighter and brighter as it appeared to travel faster in time relative to you until it reached a maximum (at which point it might vaporize you because of the massive amount of energy hitting you) at the event horizon before suddenly going dark? After that, I don't have the physics knowledge to make a good guess (and there's a singularity anyway).
Well. Off the top of my head, I know a few things about this scenario. First, the light would be strongly blueshifted. This is because of time dilation. Second, the light visible as you fall into a black hole would likely be
intense, but not
infinite (since there is a finite number of photons received by the black hole over its lifetime). Third, as far as I know, the inside of a black hole is not black - so you would not instantaneously go from "intense" to "pitch-black".
After a bit of research, it seems that from the
observer's perspective, the unfortunate explorer
appears to asymptotically approach the event horizon, but from the
explorer's perspective, they see the universe passing by
quickly but not
infinitely quickly as they approach the event horizon. And from inside the black hole, it is nearly impossible to determine the outside world from the photons received.
As B sees things: A falls toward the event horizon, photons from A take longer and longer to climb out of the "gravtiational well" leading to the apparent slowing down of A's clock as seen by B, and when A is at the horizon, any photon emitted by A's clock takes (formally) an infinite time to get out to B. Imagine that each person's clock emits one photon for each tick of the clock, to make it easy to think about. Thus, A appears to freeze, as seen by B, just as you say. However, A has crossed the event horizon! It is only an illusion (literally an "optical" illusion) that makes B think A never crosses the horizon.
As A sees things: A falls, and crosses the horizon (in perhaps a very short time). A sees B's clock emitting photons, but A is rushing away from B, and so never gets to collect more than a finite number of those photons before crossing the event horizon. (If you wish, you can think of this as due to a cancellation of the gravitational time dilation by a doppler effect --- due to the motion of A away from B). After crossing the event horizon, the photons coming in from above are not easily sorted out by origin, so A cannot figure out how B's clock continued to tick.
A finite number of photons were emitted by A before A crossed the horizon, and a finite number of photons were emitted by B (and collected by A) before A crossed the horizon. (Source)
EDIT: With regards to black holes, aren't they kind of funky in terms of entering them?
First off, once past the event horizon, space is so warped that every direction leads towards the singularity (so even if you could, theoretically, go faster than light, you'd be unable to escape without the ability to un-warp space)
That sounds right, though that is considerably funky. Do you have a source on that?
Second, from what I've been told, space=time thanks to black holes basically telling common, everyday physics to fuck themselves.
Space
equals time? That is even more funky. I found a
source for this one, and it is
cool.And third, again from what I've been told, it's not technically possible to actually enter the event horizon. The gravity is so strong that time dilates more and more and more. To an outside observer, you start to slow down, and stop right outside the horizon, but to you everything is fine, then suddenly there's a massive explosion as the black hole evaporates, and suddenly you're trillions of years in the future.
This is incorrect. That's only from the
outside observer's perspective - if you can survive the radiation and tidal forces, you
can observe yourself entering a black hole.
sourcePPE: What would falling into a black hole look like, though? Wouldn't the universe around you get brighter and brighter as it appeared to travel faster in time relative to you until it reached a maximum (at which point it might vaporize you because of the massive amount of energy hitting you) at the event horizon before suddenly going dark? After that, I don't have the physics knowledge to make a good guess (and there's a singularity anyway).
Actually, since nothing can exit the event horizon, wouldn't it rip your atoms to shreds by dint of Proton A being past the horizon and no longer being able to be next to Neutron B, since that's still outside the horizon?
If nothing else it would cause some electron stripping, which would make everything inside very much on fire.
I'm no expert, but I have a gut feeling that since spacetime "tilts" (i.e., time and space change direction; see
here) gradually as you approach the event horizon, this probably won't completely disrupt all matter passing through. That's hardly a rigorous proof though, so if you have more information, I'd love to hear more.
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Topic: Things that made you go "WTF?" today o_O (Read 14924805 times)