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As far as I understand, if the “empty skies” regions even exist, we physically will _never_ be able to observe them, because due to cosmic expansion they are mo

As far as I understand, if the “empty skies” regions even exist, we physically will _never_ be able to observe them, because due to cosmic expansion they are moving away from us faster than speed of light. So from our point of view, we can never know if universe is actually infinitely distributed or not.

dr_dshiv 4y ago
Well, just because we can’t reach the emptiness doesn’t mean we wouldn’t be able to observe the trend — of less and less stars towards the edge.
- polishdude20 4y ago
  Isn't that the whole thing about the fact that when we look at any patch of sky, we don't see it just lit up with stars filling all of it ? Like if it was infinite and we had infinite stars randomly distributed, there's be a patch of sky where we'd have an infinite amount of stars in front of eachother. The fact that we do see darkness between stars indicates that there is some portion of the universe that has an edge. Then again, there's the matter of looking so far back that you can't see stars because it's so old and thus it's not that there is an edge but just that we can't observe one.
  - nlitened 4y ago
    But we _do_ see a uniform glow from every single point in the sky, it’s called Cosmic Microwave Background. We don’t see it with a naked eye because the light’s frequency has been red-shifted, the light is coming from so far away in space and time, that universe grew so much since then and stretched its wave length. There’s no “darkness between stars”, we see there an image of universe so old that stars didn’t even form yet, and it’s uniform and infinite where it’s physically possible for us to see due to speed of light limit.
  - withinboredom 4y ago
    > Isn't that the whole thing about the fact that when we look at any patch of sky, we don't see it just lit up with stars filling all of it ? Like if it was infinite and we had infinite stars randomly distributed, there's be a patch of sky where we'd have an infinite amount of stars in front of eachother. That would require stars to be outputting infinite energy in the form of light we can see. They are not, so we do get enough of their light to see them with the naked eye. The farther away they are, the less and less photons make it to our eyes. So, yes, you can look up in the night sky and see infinite galaxies, but your eyes are not sensitive enough to pick out the one or two photons every few seconds and tell you there is something there. However, we have tools to do that for us: https://www.space.com/17755-farthest-universe-view-hubble-space-telescope.html https://www.space.com/17755-farthest-universe-view-hubble-sp...

dr_dshiv 4y ago

Well, just because we can’t reach the emptiness doesn’t mean we wouldn’t be able to observe the trend — of less and less stars towards the edge.

polishdude20 4y ago
Isn't that the whole thing about the fact that when we look at any patch of sky, we don't see it just lit up with stars filling all of it ? Like if it was infinite and we had infinite stars randomly distributed, there's be a patch of sky where we'd have an infinite amount of stars in front of eachother. The fact that we do see darkness between stars indicates that there is some portion of the universe that has an edge. Then again, there's the matter of looking so far back that you can't see stars because it's so old and thus it's not that there is an edge but just that we can't observe one.
- nlitened 4y ago
  But we _do_ see a uniform glow from every single point in the sky, it’s called Cosmic Microwave Background. We don’t see it with a naked eye because the light’s frequency has been red-shifted, the light is coming from so far away in space and time, that universe grew so much since then and stretched its wave length. There’s no “darkness between stars”, we see there an image of universe so old that stars didn’t even form yet, and it’s uniform and infinite where it’s physically possible for us to see due to speed of light limit.
- withinboredom 4y ago
  > Isn't that the whole thing about the fact that when we look at any patch of sky, we don't see it just lit up with stars filling all of it ? Like if it was infinite and we had infinite stars randomly distributed, there's be a patch of sky where we'd have an infinite amount of stars in front of eachother. That would require stars to be outputting infinite energy in the form of light we can see. They are not, so we do get enough of their light to see them with the naked eye. The farther away they are, the less and less photons make it to our eyes. So, yes, you can look up in the night sky and see infinite galaxies, but your eyes are not sensitive enough to pick out the one or two photons every few seconds and tell you there is something there. However, we have tools to do that for us: https://www.space.com/17755-farthest-universe-view-hubble-space-telescope.html https://www.space.com/17755-farthest-universe-view-hubble-sp...