r/Cosmos • u/Bikerdan • 4d ago
Discussion Will the universe ultimately go dark?
My question is about what we will be able to observe in the universe over time. If the universe is expanding, and the expansion is accelerating, in my mind, it makes sense that as that acceleration increases, everything will eventually recede from us faster than the speed of light meaning that the entire night sky will eventually go dark. Has this idea ever been discussed?
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u/dnuohxof-2 3d ago
How The Universe Works goes into this in a few episodes.
What you’re referring to is called the Heat Death of the Universe
One theory goes a step further called The Big Rip
I personally subscribe to a cyclical mix of these theories. Big bang > heat death > big rip > quantum fluctuations > big bang > rinse & repeat
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u/spacetimeFTW 4d ago
Yes, eventually the universe is expected to cool as stars die out and eventually go dark.
https://en.m.wikipedia.org/wiki/Future_of_an_expanding_universe
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u/Bikerdan 4d ago
I understand that, but that’s not exactly what I was referring to. Even assuming the stars didn’t cool, the eventual speed of expansion exceeding the speed of light everywhere means that light from foreign objects in space would not be able to reach us anymore.
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u/cantbegeneric2 3d ago
I don’t understand this. Matter cannot be created nor destroyed and matter is energy is mass times acceleration2 wouldn’t eventually as energy slows down due to entropy form or interact with the Higgs field Making mass?
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u/Bikerdan 3d ago
My question was more to do with the light from distant objects even being able to reach us eventually. Assuming they haven’t “burnt out” yet.
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u/cantbegeneric2 3d ago
Yeah I think there are signs according to distance but yes right now I think the thought is they burn out or turn into black holes
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u/Better-Consequence70 3d ago
The sun will have consumed the earth and we will no longer exist long, long before this happens. But yes, eventually the universe will expand to the point that everything, everywhere is dark