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I've been following this news for the past couple of weeks-- in essence your statement is what they are hypothesizing, and that the "something at the center tha

I've been following this news for the past couple of weeks-- in essence your statement is what they are hypothesizing, and that the "something at the center that unites the two poles" might be that we are within a black hole. https://en.wikipedia.org/wiki/Black_hole_cosmology https://en.wikipedia.org/wiki/Black_hole_cosmology for the curious.

nashashmi 1y ago
“The universe is an orb and that orb is rotating causing all the other stuff to spiral.” This was a long held theory of mine because I could not understand why a galaxy would spiral. I think there is a men in black scene, where an alien is rotating the universe globe like a toy they are playing.
- rdtsc 1y ago
  > This was a long held theory of mine because I could not understand why a galaxy would spiral. I think in general it would be unusual if they didn’t rotate. Any large non-uniform mass of gas or rocks when colliding will induce some rotation. What is odd though is that for galaxies we see more of them spinning one way than another.
- eightysixfour 1y ago
  Doesn’t it have to spiral? Think of the gravity well, anything not orbiting is just falling. The only things not racing towards the black hole at the center of the galaxy are the ones that are orbiting.
  - nashashmi 1y ago
    It can be directly sucked into the center. A spiral implies a lateral movement plus a centripetal force
    - eightysixfour 1y ago
      Right, I guess what I am saying is if it didn't spiral, it wouldn't be a galaxy for "long." It would just be a super massive black hole.
      - lolc 1y ago
        The trick to having a galaxy is for mass to fall towards the black hole and miss it all the time.
- soulofmischief 1y ago
  Ok but what is making the universe spin? This kind of theory is turtles all the way down.
  - irrational 1y ago
    Is this getting into questions like "Where did the singularity come from?" and "What came before the singularity?". We don't have a way to answer these kinds of questions.
    - soulofmischief 1y ago
      My point is that it's not much helpful to say, "galaxies spin a certain way because the universe spins", because it shifts the problem without actually answering the "why". "Turtles all the way down" is a saying about such infinite regress. https://en.wikipedia.org/wiki/Turtles_all_the_way_down https://en.wikipedia.org/wiki/Turtles_all_the_way_down And yes, I'm familiar with Dawkins' famous retort when someone asked how magnets repel things.
      - thaumasiotes 1y ago
        > And yes, I'm familiar with Dawkins' famous retort when someone asked how magnets repel things. I'm not. I was unable to substantiate that anyone named Dawkins, Richard or otherwise, made or is popularly associated with a comment about magnets. What was the retort?
        soulofmischief 1y ago
        I deeply apologize, it was late and I mixed up my Richards. :) https://youtube.com/watch?v=36GT2zI8lVA https://youtube.com/watch?v=36GT2zI8lVA
askonomm 1y ago
It was my understanding that if two black holes collide, they just form a bigger black hole, but we know there's a black hole in our universe, which then would mean that there's a black hole inside of a black hole that did not merge with the parent black hole, right? Is that something that is considered possible?
- blueflow 1y ago
  The inner black hole did not come from the outside, it formed inside and if i had to guess, it is stuck in the inside together with all the other matter, unable to interact with the outside of the outer black hole.
  - askonomm 1y ago
    Just thinking about this infinite recursion gives me the mental equivalent of a stack overflow.
    - jug 1y ago
      Maybe generating a stack overflow was the true depiction of God!
    - jfengel 1y ago
      The trick is that bigger black holes are less dense. Supermassive black holes can have the density of water. If the universe is gravitationally closed, it would have the density of... well, just look up at night. (Actually much less than that; you see more stars because you're inside a galaxy.) The density makes the scale recursion less mysterious.
      - drusenko 1y ago
        That’s interesting! When you are referring to density, are you referring to average density within the event horizon? Isn’t most (effectively all) matter concentrated in the singularity? Would love to hear you elaborate on this thought further.
bencyoung 1y ago
From what I remembe of Undergrad physics this isn't actually possible. According to GR, within an event horizon, space-like pths become "time-like" which effecitvely means the singularity is unavoidably "in the future". No matter how big a black hole is, you can't just drift around inside it as literally all paths lead downward (hence even light not escaping) If you were inside a black hole you wouldn't be able to see light from "deeper" because it wouldn't be able to travel towards you. This is not what we see within the universe, so I don't think we can be inside a black hole
- kadoban 1y ago
  All paths _eventually_ lead downward. Is there any limit to how long? Can't we just be near the outside of the blackhole and can't see the doom yet?
  - bencyoung 1y ago
    There are no stable orbits inside the event horizon, and my understanding is even things like atom vibration can't move further from the sigularity so I'm guessing timespans would be limited!
    - kadoban 1y ago
      Interesting, thanks. That does sound like you could tell from inside if you there or not. I'll have to read up on that, I always had the vague sense that on ~finite scale of time there existed a region of space where you couldn't really tell the difference if you're inside of a big enough black hole or not. Which sounds like I'm probably just wrong.
      - bencyoung 1y ago
        It's the usual rabbit hole if you search for it, but there are some useful comments here: https://astronomy.stackexchange.com/questions/58610/would-it-be-theoretically-possible-for-something-to-orbit-a-black-hole-inside-it#:~:text=There%20are%20no%20closed%20orbits,away%20from%20the%20black%20hole. https://astronomy.stackexchange.com/questions/58610/would-it... The way I see it is every surface inside an event horizon is another slightly "stronger" event horizon

nashashmi 1y ago

“The universe is an orb and that orb is rotating causing all the other stuff to spiral.” This was a long held theory of mine because I could not understand why a galaxy would spiral. I think there is a men in black scene, where an alien is rotating the universe globe like a toy they are playing.

rdtsc 1y ago
> This was a long held theory of mine because I could not understand why a galaxy would spiral. I think in general it would be unusual if they didn’t rotate. Any large non-uniform mass of gas or rocks when colliding will induce some rotation. What is odd though is that for galaxies we see more of them spinning one way than another.
eightysixfour 1y ago
Doesn’t it have to spiral? Think of the gravity well, anything not orbiting is just falling. The only things not racing towards the black hole at the center of the galaxy are the ones that are orbiting.
- nashashmi 1y ago
  It can be directly sucked into the center. A spiral implies a lateral movement plus a centripetal force
  - eightysixfour 1y ago
    Right, I guess what I am saying is if it didn't spiral, it wouldn't be a galaxy for "long." It would just be a super massive black hole.
    - lolc 1y ago
      The trick to having a galaxy is for mass to fall towards the black hole and miss it all the time.
soulofmischief 1y ago
Ok but what is making the universe spin? This kind of theory is turtles all the way down.
- irrational 1y ago
  Is this getting into questions like "Where did the singularity come from?" and "What came before the singularity?". We don't have a way to answer these kinds of questions.
  - soulofmischief 1y ago
    My point is that it's not much helpful to say, "galaxies spin a certain way because the universe spins", because it shifts the problem without actually answering the "why". "Turtles all the way down" is a saying about such infinite regress. https://en.wikipedia.org/wiki/Turtles_all_the_way_down https://en.wikipedia.org/wiki/Turtles_all_the_way_down And yes, I'm familiar with Dawkins' famous retort when someone asked how magnets repel things.
    - thaumasiotes 1y ago
      > And yes, I'm familiar with Dawkins' famous retort when someone asked how magnets repel things. I'm not. I was unable to substantiate that anyone named Dawkins, Richard or otherwise, made or is popularly associated with a comment about magnets. What was the retort?
      - soulofmischief 1y ago
        I deeply apologize, it was late and I mixed up my Richards. :) https://youtube.com/watch?v=36GT2zI8lVA https://youtube.com/watch?v=36GT2zI8lVA

askonomm 1y ago

It was my understanding that if two black holes collide, they just form a bigger black hole, but we know there's a black hole in our universe, which then would mean that there's a black hole inside of a black hole that did not merge with the parent black hole, right? Is that something that is considered possible?

blueflow 1y ago
The inner black hole did not come from the outside, it formed inside and if i had to guess, it is stuck in the inside together with all the other matter, unable to interact with the outside of the outer black hole.
- askonomm 1y ago
  Just thinking about this infinite recursion gives me the mental equivalent of a stack overflow.
  - jug 1y ago
    Maybe generating a stack overflow was the true depiction of God!
  - jfengel 1y ago
    The trick is that bigger black holes are less dense. Supermassive black holes can have the density of water. If the universe is gravitationally closed, it would have the density of... well, just look up at night. (Actually much less than that; you see more stars because you're inside a galaxy.) The density makes the scale recursion less mysterious.
    - drusenko 1y ago
      That’s interesting! When you are referring to density, are you referring to average density within the event horizon? Isn’t most (effectively all) matter concentrated in the singularity? Would love to hear you elaborate on this thought further.

bencyoung 1y ago

From what I remembe of Undergrad physics this isn't actually possible. According to GR, within an event horizon, space-like pths become "time-like" which effecitvely means the singularity is unavoidably "in the future". No matter how big a black hole is, you can't just drift around inside it as literally all paths lead downward (hence even light not escaping) If you were inside a black hole you wouldn't be able to see light from "deeper" because it wouldn't be able to travel towards you. This is not what we see within the universe, so I don't think we can be inside a black hole

kadoban 1y ago
All paths _eventually_ lead downward. Is there any limit to how long? Can't we just be near the outside of the blackhole and can't see the doom yet?
- bencyoung 1y ago
  There are no stable orbits inside the event horizon, and my understanding is even things like atom vibration can't move further from the sigularity so I'm guessing timespans would be limited!
  - kadoban 1y ago
    Interesting, thanks. That does sound like you could tell from inside if you there or not. I'll have to read up on that, I always had the vague sense that on ~finite scale of time there existed a region of space where you couldn't really tell the difference if you're inside of a big enough black hole or not. Which sounds like I'm probably just wrong.
    - bencyoung 1y ago
      It's the usual rabbit hole if you search for it, but there are some useful comments here: https://astronomy.stackexchange.com/questions/58610/would-it-be-theoretically-possible-for-something-to-orbit-a-black-hole-inside-it#:~:text=There%20are%20no%20closed%20orbits,away%20from%20the%20black%20hole. https://astronomy.stackexchange.com/questions/58610/would-it... The way I see it is every surface inside an event horizon is another slightly "stronger" event horizon