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Nothing stayed where the big bang was, but everything flew away at the same speed. There is a flaw in your imagination, because as a being in 3D you probably c

Nothing stayed where the big bang was, but everything flew away at the same speed. There is a flaw in your imagination, because as a being in 3D you probably cannot imagine how a 3D thing explodes (I certainly can't). Don't think of the universe as sphere-shaped -- it is not a 3D sphere. Think of it as the 3D surface of a 4D sphere. Why? Let's reduce by one dimension to be able to imagine this: imagine a small thing (a grain of sand) explodes in our 3D world and all the tiny pieces are flying away at equal speed, then the structure that is created by the explosion is not a 3D sphere, but the surface of a sphere, a 2D structure, because where the explosion started, there is nothing left of the original thing, as every particle of it has moved away from that point, so at any point in time after the start of the explosion, the particles are on the surface of a sphere. That surface is a 2D structure embedded into our 3D world, much like the surface of an expanding balloon. In the same way, our universe is a 3D structure, so looked at from the outside (which we obviously cannot do), it is not a 3D sphere, but probably more like the surface of a 4D sphere. Now imagine us as a dot on a balloon that is expanding, and other stars are also dots on the surface of the balloon. In whichever direction you look, all the stars are moving away from you (the balloon is expanding). You do not need a center of this structure to observe this moving away -- nothing is in the center -- there is no center.

dr_dshiv 4y ago
Your argument and examples actually don’t imply that there is no center. The Big Bang wasnt an explosion per se, but in so far as there is a 3D spatial distribution that is not infinite, there will be parts with empty skies—-that is, edges, last stars, ends of the universe.
- nlitened 4y ago
  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...
- fsckboy 4y ago
  Your argument and examples actually don’t imply that there is no center if the 4th dimension is time, the argument implies that the center is "a long time ago"
  - dr_dshiv 4y ago
    Yeah, but the heat death end of the universe is way further in the future than the Big Bang is in the past.
- LeifCarrotson 4y ago
  The argument is for a 2D observer. You and I both see that the surface area of a sand grain, distributed by explosion to a different surface area with the diameter of a beach ball, has a center in 3D space. But from the perspective of a Flatlander on the expanding surface, looking at the distance to an adjacent microbe, the universe is growing, and there is no meaningful point on that 2D surface from which the expansion emanates, it's expanding everywhere. There's no reason to believe our universe is not infinite. It's certainly effectively so.

dr_dshiv 4y ago

Your argument and examples actually don’t imply that there is no center. The Big Bang wasnt an explosion per se, but in so far as there is a 3D spatial distribution that is not infinite, there will be parts with empty skies—-that is, edges, last stars, ends of the universe.

nlitened 4y ago
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...
fsckboy 4y ago
Your argument and examples actually don’t imply that there is no center if the 4th dimension is time, the argument implies that the center is "a long time ago"
- dr_dshiv 4y ago
  Yeah, but the heat death end of the universe is way further in the future than the Big Bang is in the past.
LeifCarrotson 4y ago
The argument is for a 2D observer. You and I both see that the surface area of a sand grain, distributed by explosion to a different surface area with the diameter of a beach ball, has a center in 3D space. But from the perspective of a Flatlander on the expanding surface, looking at the distance to an adjacent microbe, the universe is growing, and there is no meaningful point on that 2D surface from which the expansion emanates, it's expanding everywhere. There's no reason to believe our universe is not infinite. It's certainly effectively so.