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2019-04-03: The Edge of an Infinite Universe

  • 00:46: It’s boundary is called the particle horizon.
  • 01:22: To review: the particle horizon defines the limit of the visible past, and there’s also cosmic event horizon defining the limit of the visible future.

2016-03-02: What’s Wrong With the Big Bang Theory?

  • 07:05: Another way to say this is that those edges of the universe have always been beyond each other's particle horizons.

2015-10-07: The Speed of Light is NOT About Light

  • 11:17: RedomaxRedomax asks what you would see if you traveled 18 times the distance to the particle horizon to come back to where you started.
  • 11:26: ... that number, 18 times the particle horizon, only applies if the universe has positive curvature, making it a ...

2015-09-30: What Happens At The Edge Of The Universe?

  • 01:47: We call this the particle horizon of the universe.
  • 01:56: Anything inside the particle horizon is referred to as the known universe.
  • 02:33: To travel to the particle horizon, we need to move through expanding space.
  • 03:33: The event horizon of the universe is actually closer to us than the particle horizon.
  • 04:22: But for now, let's just assume we have a nice Alcubierre-class warp-ship and we burn the mass energy of entire stars to chase the particle horizon.
  • 04:36: Remember, the particle horizon is just defined by the limit of our current view.
  • 04:43: Wait a minute, and my particle horizon expands.
  • 04:46: Travel to the particle horizon instantaneously and you'll see the Milky Way as a cute baby CMB blob on your new particle horizon.
  • 05:37: So if it's true, what happens if you cross the particle horizon?
  • 06:46: ... you'd need to travel an absolute minimum of 18 times the distance to the particle horizon to get back to where you started, assuming expansion froze for the whole ...
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