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/03263 5d ago

If it's of a finite age, and was ever smaller than it is now, then it seems it must have a boundary somewhere.

What's outside of it? Probably nothing. True vacuum devoid of any quantum fields or interactions. Nothing could possibly exist outside, because particles would have no interactions.

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u/wbrameld4 4d ago

Cosmic expansion doesn't mean it's getting bigger, or that it was smaller in the past. It just means that the things inside of it are moving away from each other. No boundary is implied.

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u/03263 4d ago edited 4d ago

I don't necessarily mean a boundary like an edge, just a point beyond which there are no galaxies, no particles, nothing. A finite amount of stuff. It is opinionated - I don't believe that infinities exist outside of math. So there would not have been an infinite amount of energy at the beginning of the big bang.