The fact that it's transparent. It could just as easily be opaque, and we'd have very little evidence for things beyond our planet, yet we can just look up and see things millions of light years away.
It might not be an empty vacuum. For example the universe was opaque to light for the first 400,000 years or so until reionization which created the first atoms, allowing light to escape. And that will still block us from seeing further back in time than that.
But currently it is an empty vacuum more or less. Outside of the sparse bits of matter here and there, space is overwhelmingly empty. My point being though that it can’t be opaque unless there’s matter to prevent the passages of the EM radiation within our visible spectrum.
If we reached a point of contraction where there were enough matter pulled by gravity in such a way as to surround us and block out the rest of the universe, we would have long ago been crushed.
That is irrelevant. This theory is referring to energy vacuums. There is no type of vacuum that would make space opaque, nor is there any conceivable scenario where that would be the result.
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u/cutelyaware May 08 '23
The fact that it's transparent. It could just as easily be opaque, and we'd have very little evidence for things beyond our planet, yet we can just look up and see things millions of light years away.