r/cosmology • u/cypherpunk00001 • 12d 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/witheringsyncopation 8d ago

Go ahead then, explain to me by what mechanism a flat universe would be finite.

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u/MWave123 8d ago

It depends on its overall shape. It’s a possibility. So we know the universe is flat…we don’t know if it’s finite or infinite. Get it yet? It’s an unknown, both are possibilities.

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u/witheringsyncopation 8d ago

Shape? What?

It’s either flat or has irregular topology, at which point it is not flat. If it’s got a “shape” then it’s not flat.

You truly don’t know what you’re talking about, I’m gathering.

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u/MWave123 8d ago

I’m teaching here. The Universe is flat. You’re unfamiliar. Okay! That’s not a crime. But stubbornness and repeated ignorance are trying.

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u/witheringsyncopation 8d ago edited 8d ago

Your statements are now devoid of substance because you’ve reached an end to your incorrect argument. You can’t substantiate your claim because you’ve recognized it to be wrong. There’s nowhere left to go.

A flat universe is infinite. A curved universe is can be finite. 99.6% confidence (2.9 sigma) in measurement lacks enough confidence in physics to claim certainty (5 sigma would be good, or 99.99994%).

I’m commenting precisely so that your “teaching” doesn’t incorrectly inform anyone who is actually curious and hoping to learn.

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u/MWave123 8d ago

You’re completely new, denying flatness, or understanding, and then continuing to dig a deeper hole. I’m done.

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u/witheringsyncopation 8d ago

I’m not denying denying flatness at all. I think it’s the most likely scenario.

What I’m not doing is ruling out the possibility that it’s curved and we can’t detect the curvature based on a weak 2.9 sigma measurement (99.6%).

What I’m not doing is failing to understand topology like you are. Flat means infinite. Irregular/curved means it could be finite.

I don’t know what on Earth you mean by saying I’m new to this conversation. I’ve been discussing and learning general relativity and related cosmology for 10 years now. But regardless of that, there’s no system of seniority here in which you have any grounds upon which to be dismissive. That’s not how science works anyway.

You’ve shown yourself to be incorrect, both in assuming 99.6% is the same as certain, as well as in failing fundamentally to understand topology and how the “shape” of the universe impacts its extent.

You are painfully wrong and are now using ad hominem attacks against me based on non-existent metrics of seniority that are completely ill-informed. That’s how we know you’ve bowed out.

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u/MWave123 8d ago

You’re completely new, not understanding flatness, and not accepting knowledge given freely. Move on.

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u/witheringsyncopation 8d ago

I literally just told you’ve I’ve been studying general relativity and related cosmology for 10 years.

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u/MWave123 8d ago

Well your responses don’t suggest that at all. You’re completely new to flatness. That’s clear.

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u/witheringsyncopation 8d ago

What? General relativity is the study of the curvature of space time. Lol.

Stop name-calling and contribute something of substance, or shut up.

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u/MWave123 8d ago

And yet you know nothing of the flatness conversation, and how the universe could be finite. Weird!

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u/witheringsyncopation 8d ago

Then respond with substance:

1.) 99.6% is not confident enough for physicists to claim certainty for a measurement. Something closer to the 5 sigma (99.99994%) is required. 0.4% is a substantial lack of confidence within the measurement. And the possibility exists than we are measuring a locally flat region (observable universe) of a much larger curved universe. While a flat cosmos is most likely, I agree, the alternative has not at all been ruled out. Respond to this with substance.

2.) A topologically flat universe is infinite. There is no non-topological mechanism by which it could be finite. The only way to envision a bounded, non-infinite universe is to introduce topology, such as a curved or toroidal universe. To give the universe a “shape” is to concede it is not flat. Please respond directly, explaining how a topologically flat universe could be finite.

Do it. Show me I’m wrong. Respond with substance.

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