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I think it feels weird because we define universe as having neither outside nor boundaries. There's a contradiction in terms. It ceases to feel strange as soon
by thibauts 9y ago
I think it feels weird because we define universe as having neither outside nor boundaries. There's a contradiction in terms. It ceases to feel strange as soon as you update the concept to something that has a boundary either in its spacial extension or through some kind of extra dimension.
- Baeocystin 9y agoThe analogy I use to explain this to people is simply how it is impossible to go further south than the South Pole. There is no physical barrier stopping you from moving in any direction, but due to the shape of the Earth you have reached the southernmost point. It is likely the same with our universe, and its inherent morphology, too.
- raattgift 9y ago> we define universe as having neither outside nor boundaries Do we? > boundaries There's one at the Big Bang. You can go through contortions to try to remove it (Hartle & Hawking's "no boundary proposal"; Carroll & Chen's "two-ways-to-de-Sitter from arbitrary initial surface") but so far attempts have come at the cost of introducing a lot more conceptual baggage. > outside "more of mostly the same" unless you think that one metre or one light year or two hundred million light years beyond the Hubble radius the universe is vastly different from the stars and galaxies we have around here. What could have happened to early galaxies that 200 million years ago were in principle observable from the Milky Way, such that they wouldn't now resemble the descendants of early galaxies that are 200 million light years closer to us?