Search PBS Space Time


2022-05-04: Space DOES NOT Expand Everywhere

  • 04:26: ... - at any one instant it’s a fair representation of a 2-D slice out of a closed universe,   and its growth represents the increase in the scale factor over ...

2022-04-20: Does the Universe Create Itself?

  • 15:24: ... - close, open, flat - dictates the “temporal shape”. As in does a closed universe necessarily collapse, and an open one expand forever, and a flat one ...

2022-03-23: Where Is The Center of The Universe?

  • 05:56: And that’s the most straightforward interpretation of the FLRW metric for a closed universe.
  • 06:21: In the case of the closed universe, that means it started out as a very, very tiny hypersphere surface and got bigger.
  • 07:39: ... line loops around the closed universe as the sphere shrinks, until eventually all points in the universe, ...
  • 09:52: In the case of the closed universe that’s easier to imagine - rewind the growing sphere and it approaches a single point at t=0.

2021-01-26: Is Dark Matter Made of Particles?

  • 13:39: Would a spaceship traveling near the speed of light cause a closed universe to contract so much that it would smash into its own ass?

2021-01-19: Can We Break the Universe?

  • 02:33: ... also imagine that we live in a closed universe - one that loops back on itself, so by traveling far enough you can get ...
  • 05:46: Our ultimate question is about a spaceship crashing into itself in a closed universe - and trust me we’re getting there.
  • 05:53: Let’s first look at the twin paradox in a closed universe.
  • 07:25: It seems that in this closed universe there IS a fundamental difference between frames of reference.
  • 07:54: In the case of the closed universe, that closed topology DOES pick out a special frame - it’s the one with these closed constant time loops.
  • 10:48: Does a near-light-speed spaceship smash into it’s own rear-end in a closed universe?
  • 11:01: ... happens to a ladder in a pacman barn, or a spaceship in a closed universe, when the barn or universe are length contracted to be smaller than the ...
  • 11:54: Long story short -near-light-speed spaceships in closed universes or ladders in pacman barns are safe from colliding with their own asses.

2019-12-09: The Doomsday Argument

  • 16:21: ... some wisdom from Ethan Seigel, whose excellent Forbes article on this closed universe paper emphasized a point that we mentioned only in passing that is worth ...

2019-12-02: Is The Universe Finite?

  • 01:02: ... Nature Astronomy paper that just reported this: Planck evidence for a closed Universe and a possible crisis for cosmology by Eleonora Di Valentino, Alessandro ...

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

  • 02:35: ... only type of non-infinite universe – or closed universe – is the one that curves back on itself – like a 3-D analog of the 2-D ...
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