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My understanding is the transition to a white hole exists instead of a singularity at the interior of the black hole, and is therefore hidden by the event horiz

by enkid 8y ago

My understanding is the transition to a white hole exists instead of a singularity at the interior of the black hole, and is therefore hidden by the event horizon. When the event horizon shrinks to the Planck length, the white hole is exposed.

nabla9 8y ago
Yes, but the event horizon shrinks by emitting Hawking radiation, right? When the white hole is exposed, what it looks like? Is it just hole in the space that does not emit anything? Nothing exits (because Hawking radiation already emitted all of the energy) and nothing can enter. What is the radius of the white hole?
- ianai 8y ago
  I think Roger Penrose’s explanation here is appropriate, but I don’t know if the similarity between a black holes evaporation and the eventual entropy death of the universe are similar enough: https://youtube.com/watch?v=z2_6h15UCMg https://youtube.com/watch?v=z2_6h15UCMg. If so, I think it would mean a Plankt scale black hole would have a significant probability of spontaneously evolving a white hole?
  - nabla9 8y ago
    I just listened Sean Carrol's podcast interview wit Penrose and I think they are different. https://www.preposterousuniverse.com/podcast/2019/01/07/episode-28-roger-penrose-on-spacetime-consciousness-and-the-universe/ https://www.preposterousuniverse.com/podcast/2019/01/07/epis... In the loop quantum gravity there is a bounce because at the lowest level spacetime is discrete and can't be compressed. The big bounce theory of relating to big bang in the loop quantum theory might be similar to the black hole/white hole theory. In Penrose's theory it's the gravity/mass that is creating time and clumping things together between the big bang and the heat death of the universe (you need mass to create clock and time). At the beginning of the universe temperature was so high that masses did not matter, at the end of the universe there is no mass, just massless particles (after googol or so when the biggest black holes have evaporated). Massless particles (photon, gluon, graviton) don't experience time so they in a sense fly into the the end of the eternity instantly. Then there is something geometrical I don't understand and the ends meet and the new universe matches the end of the previous across timeless eon. Penrose thinks you could perceive the ripples caused by the massive black holes from the last universe in the background radiation of our universe.
    - ianai 8y ago
      I think it’s like a duality or equivalence through asymptotic states. Ie old universe becomes timeless energy and new univese.
      - nabla9 8y ago
        LQG and big bounce requires big bang and expansion being followed with contraction of the universe ending with big crunch at the end. Pernroses CCC (conformal cyclic cosmology) is a big bang followed by an infinite future expansion and timelike infinity.

by enkid 8y ago

nabla9 8y ago

Yes, but the event horizon shrinks by emitting Hawking radiation, right? When the white hole is exposed, what it looks like? Is it just hole in the space that does not emit anything? Nothing exits (because Hawking radiation already emitted all of the energy) and nothing can enter. What is the radius of the white hole?

ianai 8y ago
I think Roger Penrose’s explanation here is appropriate, but I don’t know if the similarity between a black holes evaporation and the eventual entropy death of the universe are similar enough: https://youtube.com/watch?v=z2_6h15UCMg https://youtube.com/watch?v=z2_6h15UCMg. If so, I think it would mean a Plankt scale black hole would have a significant probability of spontaneously evolving a white hole?
- nabla9 8y ago
  I just listened Sean Carrol's podcast interview wit Penrose and I think they are different. https://www.preposterousuniverse.com/podcast/2019/01/07/episode-28-roger-penrose-on-spacetime-consciousness-and-the-universe/ https://www.preposterousuniverse.com/podcast/2019/01/07/epis... In the loop quantum gravity there is a bounce because at the lowest level spacetime is discrete and can't be compressed. The big bounce theory of relating to big bang in the loop quantum theory might be similar to the black hole/white hole theory. In Penrose's theory it's the gravity/mass that is creating time and clumping things together between the big bang and the heat death of the universe (you need mass to create clock and time). At the beginning of the universe temperature was so high that masses did not matter, at the end of the universe there is no mass, just massless particles (after googol or so when the biggest black holes have evaporated). Massless particles (photon, gluon, graviton) don't experience time so they in a sense fly into the the end of the eternity instantly. Then there is something geometrical I don't understand and the ends meet and the new universe matches the end of the previous across timeless eon. Penrose thinks you could perceive the ripples caused by the massive black holes from the last universe in the background radiation of our universe.
  - ianai 8y ago
    I think it’s like a duality or equivalence through asymptotic states. Ie old universe becomes timeless energy and new univese.
    - nabla9 8y ago
      LQG and big bounce requires big bang and expansion being followed with contraction of the universe ending with big crunch at the end. Pernroses CCC (conformal cyclic cosmology) is a big bang followed by an infinite future expansion and timelike infinity.