Far out cosmology: spacetime is flat (Introduction)

by David Turell , Thursday, July 22, 2021, 15:44 (1218 days ago) @ David Turell

Other possibilities of topology are considered:

https://www.forbes.com/sites/startswithabang/2021/07/21/why-the-universe-probably-isnt-...

"The true problem with the Universe is that there’s only one to observe, or at least, only one that we’re capable of observing. We don’t have a large sample of Universes to compare between, and we don’t have a large set of data points available to us within our Universe. It’s like rolling five dice, together, once. Your odds of getting all sixes is small: about 1-in-7800. Yet if you rolled five dice at once and saw that it came up all sixes, you wouldn’t necessarily conclude that it was anything more than random chance. Sometimes, nature just doesn’t give you the most likely outcome.

"It’s possible that the leftover photons from the Big Bang, reaching us today as a snapshot from 13.8 billion years ago, really are the result of expanding from a donut-shaped Universe, one that’s barely larger than the observational limits of what we perceive today. But the one piece of evidence we have to support that scenario isn’t particularly compelling, and cannot rule out the null hypothesis: that we live in a Universe indistinguishable from flat, simply connected, and without any fancy topological traits. Unless we find a way to extract more information from our Universe — and we’ve already pulled everything out of the cosmic microwave background that we can, to the limits of our observations — we may never be able to meaningfully discriminate between these two possibilities."

Comment: This is an enormous theoretical article basically disputing all theories but a flat universe, By Ethan Siegel, at Forbes, an Ph.D. astrophysicist, author, and science communicator, who professes physics and astronomy at various colleges.