4d ago

God is a dick.

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There is no evidence that the Universe is bounded at all. For all we know, it is infinite in spacial dimension.
- John Green: Yikes!
- True, but there is thought to be a finite amount of matter + energy, which cannot be created or destroyed. And since it is spreading out from an original dense point, it stands to reason that there would be a vacuum area that it has not reached yet.
  
  Our current understanding of the big bang is not that it spread out from one place, it happened everywhere all at once. If the universe is infinite, it started from zero volume and infinite density then immediately became infinite in volume and finite in density. The density of matter/energy is what is finite, not the amount of matter/energy, that is infinite (if the universe is infinite). Then there was a period of rapid inflation, then is settled down to the inflation we see today.
  Infinite or finite, the universe is not spreading out into anything, the distances between points are simply increasing.
  
  It's so obvious, to me, to think of the universe as occurring 'in a box'and that expansion happening like someone is inflating a balloon inside it - so we're running out of room as such.
  Take away the box and my brain just melts. I'm not very familiar with this stuff, however
  
  The important thing in the balloon analogy isn't what the balloon is expanding into, it's just that every point on the balloon is drifting away from every other point.
  One thing to consider, though, is that space may not even be a real physical thing. Maybe location is just a property of things, like mass or electrical charge. It could just be an inherent value that adjusts and influences other things according to the laws of physics. Maybe it's less that "space is expanding" and just that "the location property of everything is constantly diverging." There's no need to worry about what anything is expanding into because our conception of space may just be a mental construct.
  
  ...absolutely wild
  edit on a 2nd read it strikes me that determining whether space is expanding vs the location property of everything is diverging is a relatively impossible exercise (key word, there).
  A lot like the non-trivial thought experiments, 'prove you're in/not in a simulation'
  
  it started from zero volume
  This is not true. It started with apparently infinite volume. This is the confusing nature of infinities.
  
  Hum, no. It's widely believed that the amount of matter + energy in the universe changes all the time.
  
  That's not at all how it works. In particular, it didn't start from an original, dense point. It started everywhere, with nearly uniform density apparently infinitely in all directions. If the Universe is boundless, there is no reason to suspect the material it contains is not equally boundless.
- It may as well as it is unreachable. It hasn't existed forever hence only a limited amount of space is closer to us than the age of the universe.
- Not really. As far as we know information can't travel faster than light speed, and the oldest/farthest stuff we can see is 14 billion years old / 14b light years away. That gives us the radius and age of the observable universe.
  By our current understanding of how the universe works we can't see anything further or older than that (and will never be able to), so any assumption about things outside/before the observable universe is completely baseless

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