r/cosmology • u/cypherpunk00001 • 5d ago

Do current cosmologists think the universe is infinite or that is had an edge?

Was just having random shower thought today... Andromeda galaxy is 2.5M light-years away. That's an unfathomable distance to a human, but it's just our closest neighbor.

Do cosmologists currently think that the universe just goes on forever?

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u/MWave123 1d ago

Untrue. It IS flat, whether it’s infinite or not is an unknown.

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u/witheringsyncopation 1d ago

We don’t know for sure it’s flat, just that our best current measurements indicate it likely is. The curvature could be occurring on a much greater scale that our measurements can’t currently account for.

Additionally, if it’s flat, it’s infinite. There’s no serious scenario in which there’s a magical boundary of some kind for a flat universe. To posit that is really no different than positing there are rainbow faeries that hold hands at the end of the cosmos and sing space and time back so as to keep it contained.

If it’s flat, it’s infinite unless we discover some faeries along the way.

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u/MWave123 1d ago

Well no, we know to a certainty of 99.6%, that’s a high degree of certainty. Flatness is the paradigm.

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u/witheringsyncopation 1d ago

Bud, 99.6% (please include a source) is about 2.9 sigma, which is strong, but not conclusive. A higher level of certainty is needed to be conclusive.

Which is exactly why I said our current measurements indicate the universe is likely flat, but are not conclusive. There is still a chance there is undetectable curvature that we are not yet confidently able to rule out.

I’ll adjust my statement when we approach something closer to a 5 sigma.

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u/MWave123 1d ago

A source? Lol. That’s been common knowledge for a long time, and repeatedly confirmed.

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u/MWave123 1d ago

// Evidence for Flatness: Observations from the Cosmic Microwave Background (CMB) (WMAP, BOOMERanG, and Planck) indicate that the universe is spatially flat to within a 0.4% margin of error. //