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> Time doesn't work inside black holes, we have no clue how that even works or if things are frozen or if it happens instantly. […] This isn't just the time par

> Time doesn't work inside black holes, we have no clue how that even works or if things are frozen or if it happens instantly. […] This isn't just the time paradox of near light travel, the math says that inside black holes you have an entire different dimension of time instead of our regular one There is no such thing inside a black hole as "an entire different dimension of time." Yes, by the very definition of an event horizon, the coordinate chart of an observer at infinity cannot extend inside a black hole. Needing multiple coordinate charts is not really unusual, though. The two-dimensional sphere S² also requires at least two charts. All in all, time inside a black hole locally works the way it does outside a black hole. Yes, there might be interesting non-local effects like closed timelike curves but you can also have those outside.

Jensson 2y ago
> time inside a black hole locally works the way it does outside a black hole That doesn't mean that it actually runs though, you can interpret the lack of possible shared reference of time as the black holes time either happens instantly, but also that it never ever happens and everything in it is stuck and time is frozen from our perspective. In the time frozen perspective the singularity would never form, all objects are frozen and never reach it.
- db48x 2y ago
  Time doesn’t magically freeze inside of a black hole. That is a misunderstanding of what happens to light rays carrying the image of the infalling diver as they approach the event horizon. From the perspective of an outside observer, those light rays are slowed down more and more and light from the instant of crossing the event horizon never actually arrives; it appears to take an infinite amount of time to do so. The mistake is to think that the object is still there, hovering at the event horizon, for an infinite amount of time. The reality is that the diver notices nothing unusual as they cross the event horizon; they may not even be able to tell exactly when it happens. They certainly do not freeze in place forever.
  - Jensson 2y ago
    > The reality is that the diver notices nothing unusual as they cross the event horizon That doesn't mean that he actually crosses it from our reference frame. Relativity is all about understanding that time is relative, that applies here as well, except that there is no connection between the two reference frame unlike regular space, so we can't say anything about how time flows inside of a black hole from our perspective. Basically what I am saying is, you can't say whether the singularity has actually formed, since your reference frame is just as connected to the instant anything fell into the black hole as it is connected to the end state of the singularity. That makes it just as valid to say that things freeze the instant they touch the black hole as to say that they merge with the singularity the instant they touch it, since both are equally valid viewpoints from our perspective.
    - db48x 2y ago
      There is no disconnection between the interior of the black hole and the exterior. They are smoothly and continuously connected, and the “normal” axis of time blends seamlessly with the “bent” axis of time inside the black hole. That’s why orbits are so weird outside the black hole. You’re simply wrong about this.
      - Jensson 2y ago
        So how long does it take for a thing to enter the singularity as seen from our reference frame? If you say there is no way to answer it, then you say that I am right, so I'd like to see a link to a formula saying how long that takes from our point of view. I studied up to a masters in physics, I've seen the math, I don't believe there is a way to calculate that, there is no way to compare time inside with time outside. Edit: I'd love to see such a formula if there is one btw, so if you know there is one please link!
        qubitcoder 2y ago
        I'm not sure what you mean by "enter the singularity". Once an object has crossed the event horizon, its light rays can no longer reach us. From an outside perspective, the time required would be based on the object's orbit and when it intersected with the event horizon. When you say "thing", it's more like photons. While thought experiments of a diver falling into a black hole are fun to ponder, nature isn't so gentle. The corona, tidal forces, magnetic fields--and other factors--would obliterate matter into a stream of subatomic particles and light before crossing the event horizon. So the concept of a "thing" moving inside a black hole is likely misguided. It’s been called one of the most extreme physical environments in the universe. Strong magnetic fields threading the inner accretion disk extend out of it, creating a tenuous, turbulent, billion-degree cloud. Particles in the corona orbit the black hole at velocities approaching the speed of light. It’s a source of X-rays with much higher energies than those emanating from the accretion disk, but astronomers are still trying to figure out its extent, shape, and other characteristics. [0] NASA provides a fantastic overview here [0]. A few resources to check out: Sean Carrol, PBS Space Time, Ask a Spaceman, and Why this Universe are all great resources--and frequently do deep dives into this topic. [0] https://science.nasa.gov/universe/black-holes/anatomy/ https://science.nasa.gov/universe/black-holes/anatomy/

Jensson 2y ago

> time inside a black hole locally works the way it does outside a black hole That doesn't mean that it actually runs though, you can interpret the lack of possible shared reference of time as the black holes time either happens instantly, but also that it never ever happens and everything in it is stuck and time is frozen from our perspective. In the time frozen perspective the singularity would never form, all objects are frozen and never reach it.

db48x 2y ago
Time doesn’t magically freeze inside of a black hole. That is a misunderstanding of what happens to light rays carrying the image of the infalling diver as they approach the event horizon. From the perspective of an outside observer, those light rays are slowed down more and more and light from the instant of crossing the event horizon never actually arrives; it appears to take an infinite amount of time to do so. The mistake is to think that the object is still there, hovering at the event horizon, for an infinite amount of time. The reality is that the diver notices nothing unusual as they cross the event horizon; they may not even be able to tell exactly when it happens. They certainly do not freeze in place forever.
- Jensson 2y ago
  > The reality is that the diver notices nothing unusual as they cross the event horizon That doesn't mean that he actually crosses it from our reference frame. Relativity is all about understanding that time is relative, that applies here as well, except that there is no connection between the two reference frame unlike regular space, so we can't say anything about how time flows inside of a black hole from our perspective. Basically what I am saying is, you can't say whether the singularity has actually formed, since your reference frame is just as connected to the instant anything fell into the black hole as it is connected to the end state of the singularity. That makes it just as valid to say that things freeze the instant they touch the black hole as to say that they merge with the singularity the instant they touch it, since both are equally valid viewpoints from our perspective.
  - db48x 2y ago
    There is no disconnection between the interior of the black hole and the exterior. They are smoothly and continuously connected, and the “normal” axis of time blends seamlessly with the “bent” axis of time inside the black hole. That’s why orbits are so weird outside the black hole. You’re simply wrong about this.
    - Jensson 2y ago
      So how long does it take for a thing to enter the singularity as seen from our reference frame? If you say there is no way to answer it, then you say that I am right, so I'd like to see a link to a formula saying how long that takes from our point of view. I studied up to a masters in physics, I've seen the math, I don't believe there is a way to calculate that, there is no way to compare time inside with time outside. Edit: I'd love to see such a formula if there is one btw, so if you know there is one please link!
      - qubitcoder 2y ago
        I'm not sure what you mean by "enter the singularity". Once an object has crossed the event horizon, its light rays can no longer reach us. From an outside perspective, the time required would be based on the object's orbit and when it intersected with the event horizon. When you say "thing", it's more like photons. While thought experiments of a diver falling into a black hole are fun to ponder, nature isn't so gentle. The corona, tidal forces, magnetic fields--and other factors--would obliterate matter into a stream of subatomic particles and light before crossing the event horizon. So the concept of a "thing" moving inside a black hole is likely misguided. It’s been called one of the most extreme physical environments in the universe. Strong magnetic fields threading the inner accretion disk extend out of it, creating a tenuous, turbulent, billion-degree cloud. Particles in the corona orbit the black hole at velocities approaching the speed of light. It’s a source of X-rays with much higher energies than those emanating from the accretion disk, but astronomers are still trying to figure out its extent, shape, and other characteristics. [0] NASA provides a fantastic overview here [0]. A few resources to check out: Sean Carrol, PBS Space Time, Ask a Spaceman, and Why this Universe are all great resources--and frequently do deep dives into this topic. [0] https://science.nasa.gov/universe/black-holes/anatomy/ https://science.nasa.gov/universe/black-holes/anatomy/