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So basically it's impossible to know what is "inside" a black hole because it's not part of this universe ? But aren't black hole formed by stars that collapsed

So basically it's impossible to know what is "inside" a black hole because it's not part of this universe ? But aren't black hole formed by stars that collapsed under their own mass ? So black holes are created from objects that belong to this universe right ? I get the idea that black holes aren't like a sink. However all that matter or light that get "trapped" into it must go somewhere, in some form .

InclinedPlane 10y ago
Yep. Black holes aren't phenomena of matter, they are formed initially from matter but they are phenomena of space-time. The event horizon is basically a one way door, there's no way, no route in space-time, to cross it and return.
- ajuc 10y ago
  But black holes evaporate?
  - zamalek 10y ago
    The curvature is the cause of the event horizon, the mass or energy is the cause of the curvature. Remove energy and you remove curvature, remove the curvature and you remove the event horizon.
  - deleted 10y ago
    [deleted]
  - contravariant 10y ago
    Only if you go beyond general relativity. Once you include quantum physics there are some strong indications that black holes must somehow evaporate (although this hasn't been observed directly), but that model is still incomplete.
  - InclinedPlane 10y ago
    Yup, and that's a problem that hasn't been fully worked out yet.
- zubspace 10y ago
  So, it's an 'information' black hole, right? But matter, energy, whatever is trapped inside it with very high density and does not simply vanish right? .. Or am I completely wrong?
  - deleted 10y ago
    [deleted]
x5n1 10y ago
Not necessarily. https://en.wikipedia.org/wiki/Black_hole_information_paradox https://en.wikipedia.org/wiki/Black_hole_information_paradox
- spriggan3 10y ago
  > Information is stored in a baby universe that separates from our own universe I like this idea, but then it means that there is no universe but multiverses, yet these multiverses need to be part of a greater structure or container, right ? do we have clues that strongly suggest the multiverse theory ?
  - x5n1 10y ago
    http://www.independent.co.uk/news/science/black-holes-are-a-passage-to-another-universe-says-stephen-hawking-10471397.html http://www.independent.co.uk/news/science/black-holes-are-a-... We have many theories but little evidence of any of the theories having to do with black holes.
  - Ruud-v-A 10y ago
    From a practical point of view, the baby universe theory is no different than the “information is lost” theory. Although it might be satisfying to think that information is not “really lost”, there is no way in which we -- in our universe -- would be able to tell the difference. The distinction is philosophical, not physical. There is a different theory not mentioned prominently on that page that in my opinion provides the most useful resolution: Black Hole Complementarity. In a sense it is not a satisfying resolution, because it basically states “the paradox is not a paradox”. It is very counter-intuitive, but that is a problem with intuition. The wave-particle duality of light, which is nowadays not really considered a paradox any more although it was ~110 years ago, is a good analogy. As always happens with questions like these, in the end the answer is “that is a nonsensical question to ask”.

InclinedPlane 10y ago

Yep. Black holes aren't phenomena of matter, they are formed initially from matter but they are phenomena of space-time. The event horizon is basically a one way door, there's no way, no route in space-time, to cross it and return.

ajuc 10y ago
But black holes evaporate?
- zamalek 10y ago
  The curvature is the cause of the event horizon, the mass or energy is the cause of the curvature. Remove energy and you remove curvature, remove the curvature and you remove the event horizon.
- deleted 10y ago
  [deleted]
- contravariant 10y ago
  Only if you go beyond general relativity. Once you include quantum physics there are some strong indications that black holes must somehow evaporate (although this hasn't been observed directly), but that model is still incomplete.
- InclinedPlane 10y ago
  Yup, and that's a problem that hasn't been fully worked out yet.
zubspace 10y ago
So, it's an 'information' black hole, right? But matter, energy, whatever is trapped inside it with very high density and does not simply vanish right? .. Or am I completely wrong?
- deleted 10y ago
  [deleted]

x5n1 10y ago

Not necessarily. https://en.wikipedia.org/wiki/Black_hole_information_paradox https://en.wikipedia.org/wiki/Black_hole_information_paradox

spriggan3 10y ago
> Information is stored in a baby universe that separates from our own universe I like this idea, but then it means that there is no universe but multiverses, yet these multiverses need to be part of a greater structure or container, right ? do we have clues that strongly suggest the multiverse theory ?
- x5n1 10y ago
  http://www.independent.co.uk/news/science/black-holes-are-a-passage-to-another-universe-says-stephen-hawking-10471397.html http://www.independent.co.uk/news/science/black-holes-are-a-... We have many theories but little evidence of any of the theories having to do with black holes.
- Ruud-v-A 10y ago
  From a practical point of view, the baby universe theory is no different than the “information is lost” theory. Although it might be satisfying to think that information is not “really lost”, there is no way in which we -- in our universe -- would be able to tell the difference. The distinction is philosophical, not physical. There is a different theory not mentioned prominently on that page that in my opinion provides the most useful resolution: Black Hole Complementarity. In a sense it is not a satisfying resolution, because it basically states “the paradox is not a paradox”. It is very counter-intuitive, but that is a problem with intuition. The wave-particle duality of light, which is nowadays not really considered a paradox any more although it was ~110 years ago, is a good analogy. As always happens with questions like these, in the end the answer is “that is a nonsensical question to ask”.