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You can only get inside black hole after time ends. That's because universe-time stops at the horizon. The moment you fall in, Anne is dead eternally long ago.

You can only get inside black hole after time ends. That's because universe-time stops at the horizon. The moment you fall in, Anne is dead eternally long ago. Also, you are incinerated by a billion years of starlight per your second, including energetic particles I guess. You will observe the end of universe and death of everything in it before diving.

thomasahle 11y ago
Well, it has to be slightly more complicated than that. After all you are going to be emitted as hawking radiation a lot earlier than the end of the universe.
- deleted 11y ago
  [deleted]
- guard-of-terra 11y ago
  Large black holes have life expectancy so much larger than universe age that it's not even funny. They're not going anywhere AFAIK. No, you will stay there and watch. "The power in the Hawking radiation from a solar mass black hole turns out to be a minuscule 9 × 10−29 watts. It is indeed an extremely good approximation to call such an object 'black'."
  - tfgg 11y ago
    Larger than the current life of the universe, not necessarily longer than the end of the universe, though that really depends on your model of how it'll all end. Some do involve black holes gradually boiling away to radiation being the last things being left.
    - guard-of-terra 11y ago
      Maybe there would be an eternity of black holes boiling / protons decaying. I doubt that since something ought to lose stability in the long run.
      - logfromblammo 11y ago
        If spacetime continues to accelerate its expansion, a black hole at the future end of time might be like suddenly dropping the air pressure over a boiling pot of water--or maybe more like popping a blackhead pimple by stretching the skin on either side of it. I am not a theoretical physicist, though, so whenever I think too hard about how that would actually work, I give myself a headache and need a good lie-down in a very dark room.
tvmalsv 11y ago
If that were the case, wouldn't that mean that the moment a black hole is formed, it would never become any larger? How have super-massive black holes formed in less than 14 billion years?
- guard-of-terra 11y ago
  This is a very interesting question and I'm unaware of a definite answer.
- ars 11y ago
  The answer is both simple and controversial: They have not. Black holes do not exist because they take an infinite amount of time to form. See the thread elsewhere on this page.
  - oldmanjay 11y ago
    You're making some awfully assertive statements for not having proved your case. Dismissal of all answers as "hand-wavy" does not actually make your non-argument more compelling.
    - jdmichal 11y ago
      The concept is known as "eternally collapsing objects", and has survived peer review just as much as any other concept discussed here. http://en.wikipedia.org/wiki/Magnetospheric_eternally_collapsing_object http://en.wikipedia.org/wiki/Magnetospheric_eternally_collap... This is actually something that is verifiable, given time, since traditional black holes may not sustain their own magnetic field, but MECOs can.
repsilat 11y ago
> The moment you fall in, Anne is dead eternally long ago. Nonsense. By this logic, if you cross the event horizon feet-first, your head will have died of old age before it gets inside!
- guard-of-terra 11y ago
  It is not so, as the relative time difference between your feet and head is very small (for large black holes). There is no barrier in place of event horizon, but from the POV of external observer it takes infinite time for you to dive.
  - repsilat 11y ago
    > the relative time difference between your feet and head is very small If there's nothing significant going on between your head and your feet, there's nothing significant between your head and an "external observer" two metres above your head. Say Anne is falling in behind you, and she either decides to "back out at the last minute" or just keep falling with you. As you fall, time is passing more or less the same for the both of you, so we can just go by your clock: You cross the event horizon at t=0, she makes her decision at t=1, and she either crosses at t=2 or doesn't cross at all. Now, if Anne "backs out", her clock does diverge sharply from yours as she stops her fall and accelerates away from the event horizon, but this clock divergence happens after you've crossed the event horizon, not as you cross it or before.
    - guard-of-terra 11y ago
      "there's nothing significant between your head and an "external observer" two metres above your head." Of course, but when we talk about "external observer" far from the black hole, difference appears.

thomasahle 11y ago

Well, it has to be slightly more complicated than that. After all you are going to be emitted as hawking radiation a lot earlier than the end of the universe.

deleted 11y ago
[deleted]
guard-of-terra 11y ago
Large black holes have life expectancy so much larger than universe age that it's not even funny. They're not going anywhere AFAIK. No, you will stay there and watch. "The power in the Hawking radiation from a solar mass black hole turns out to be a minuscule 9 × 10−29 watts. It is indeed an extremely good approximation to call such an object 'black'."
- tfgg 11y ago
  Larger than the current life of the universe, not necessarily longer than the end of the universe, though that really depends on your model of how it'll all end. Some do involve black holes gradually boiling away to radiation being the last things being left.
  - guard-of-terra 11y ago
    Maybe there would be an eternity of black holes boiling / protons decaying. I doubt that since something ought to lose stability in the long run.
    - logfromblammo 11y ago
      If spacetime continues to accelerate its expansion, a black hole at the future end of time might be like suddenly dropping the air pressure over a boiling pot of water--or maybe more like popping a blackhead pimple by stretching the skin on either side of it. I am not a theoretical physicist, though, so whenever I think too hard about how that would actually work, I give myself a headache and need a good lie-down in a very dark room.

tvmalsv 11y ago

If that were the case, wouldn't that mean that the moment a black hole is formed, it would never become any larger? How have super-massive black holes formed in less than 14 billion years?

guard-of-terra 11y ago
This is a very interesting question and I'm unaware of a definite answer.
ars 11y ago
The answer is both simple and controversial: They have not. Black holes do not exist because they take an infinite amount of time to form. See the thread elsewhere on this page.
- oldmanjay 11y ago
  You're making some awfully assertive statements for not having proved your case. Dismissal of all answers as "hand-wavy" does not actually make your non-argument more compelling.
  - jdmichal 11y ago
    The concept is known as "eternally collapsing objects", and has survived peer review just as much as any other concept discussed here. http://en.wikipedia.org/wiki/Magnetospheric_eternally_collapsing_object http://en.wikipedia.org/wiki/Magnetospheric_eternally_collap... This is actually something that is verifiable, given time, since traditional black holes may not sustain their own magnetic field, but MECOs can.

repsilat 11y ago

> The moment you fall in, Anne is dead eternally long ago. Nonsense. By this logic, if you cross the event horizon feet-first, your head will have died of old age before it gets inside!

guard-of-terra 11y ago
It is not so, as the relative time difference between your feet and head is very small (for large black holes). There is no barrier in place of event horizon, but from the POV of external observer it takes infinite time for you to dive.
- repsilat 11y ago
  > the relative time difference between your feet and head is very small If there's nothing significant going on between your head and your feet, there's nothing significant between your head and an "external observer" two metres above your head. Say Anne is falling in behind you, and she either decides to "back out at the last minute" or just keep falling with you. As you fall, time is passing more or less the same for the both of you, so we can just go by your clock: You cross the event horizon at t=0, she makes her decision at t=1, and she either crosses at t=2 or doesn't cross at all. Now, if Anne "backs out", her clock does diverge sharply from yours as she stops her fall and accelerates away from the event horizon, but this clock divergence happens after you've crossed the event horizon, not as you cross it or before.
  - guard-of-terra 11y ago
    "there's nothing significant between your head and an "external observer" two metres above your head." Of course, but when we talk about "external observer" far from the black hole, difference appears.