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What is beyond the edge of the observable universe? Scientists say that the Big Bang is the cause of all creation in the known universe, but it would seem the bang must have happened in the center of the universe ?

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    $\begingroup$ The universe has no center. See this question. $\endgroup$ – StephenG Oct 28 '17 at 20:43
  • $\begingroup$ Why ? there is no center ? $\endgroup$ – PL_Pathum Oct 29 '17 at 13:07
  • $\begingroup$ Chewy butterscotch toffee. - prove me wrong. Center is impossible to find without going into surrounding higher dimensional stuff, which we don't even know for sure is there. $\endgroup$ – Wayfaring Stranger Oct 29 '17 at 14:36
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    $\begingroup$ I don't think this question should get close votes. It's a sincere question. Better to mark it a duplicate if it was already asked, or give it an answer. $\endgroup$ – userLTK Oct 29 '17 at 22:47
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    $\begingroup$ Possible duplicate of What is in the center of the universe? $\endgroup$ – zephyr Oct 30 '17 at 14:31
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What is beyond the observable universe?

There's no way to know because we can't see it. No information from the unobservable part of the universe can ever get to us. If we can't see it, we can't know what's there.

Over time, the observable universe grows and we see more of the universe, though this is actually a pretty complicated due to the rate of expansion and I'd rather not open that can of worms, but for further reading, see this question or this one.

But avoiding the complexities of dark energy expansion, we have a pretty good idea that the unobservable universe is very much like what we can see. This makes logical sense because it likely formed the same way at roughly the same time and out of the same stuff. So, we expect it's just more galaxies and more space.

In addition to this, if there was a point where the galaxies stopped being there at a theoretical 'edge', not far from the edge of the observable universe, we'd expect to see that lack of gravitation resulting in the galaxies moving away less fast and that's not observed. The galaxies appear to be moving away from us equally fast in all directions, so we have good reason to believe that the universe is uniform out considerably beyond what we can observe. It's at least several times larger than what we can see.

If we think of the big bang at happening at a point, which is often depicted in sciency-tv shows, then we shouldn't expect uniformity due to gravity and faster moving parts spreading out more, but what we see when we observe the universe is uniformity. That means that if it did explode from a singular point, it must be so large that we can't see any variation.

The more popular approach is that the big bang didn't happen at a point but it happened everywhere. Google Everywhere Stretch for some explanations of this.

It's worth noting that not all shapes (or manifolds) have centers. The surface of the Earth has no center on the surface. So even if we could see the entire universe, finding it's center might still not be possible.

Determining the center of the observable universe, however, is easy. We can see in all directions just about equally so we're the center. But we can't get a good grasp on the size and shape of the entire universe, or just universe is more correct. Since we can't see all of it, finding the center is impossible.

The bang must have happened in the center of the universe.

Keep in mind that the big bang isn't well understood. It's what physicists call a singularity which means, the math breaks down. The point exploding outwards is often represented, but shouldn't be considered accurate.

Mathematical approaches can come up with a variety of possibilities like hyperplanes intersecting or 4 or 5 dimensional spheres. (Stephen Hawking had a 5 dimensional sphere argument where no big bang happened, it's just all a circle - that's in one of his books, I think blackholes and baby universes). He was able to create a universe without a big bang. That the universe is infinite and the big bang happened across infinite space is also a popular idea today. The singular point that blew up into the universe isn't big right now, though that viewpoint still applies to the observable universe, but it's fallen out of favor for the entire universe.

My two cents anyway, as a layman.

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  • $\begingroup$ "lack of gravitation resulting in the galaxies moving away less fast". Actually, at these distances from us it's the cumulative expansion of space itself that determines the speed of recession; gravity only affects galaxies at filament or supercluster level or less. But I'd be interested to know what implications there would be for a "bubble" of mass (the observable universe) in a much vaster emptiness. Fascinating thought, but probably untestable. $\endgroup$ – Chappo Hasn't Forgotten Monica Nov 10 '17 at 1:18
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    $\begingroup$ @Chappo It's been said that the observable universe is roughly the right mass to form a black hole. That suggests to me if stuff stops not far beyond the observable universe, the gravity would be significant. But you're right about the expansion of space not gravity determining the recessive speed. If mass wasn't mostly uniform, that might no longer be true. Then again, expansion might stretch gravity the way it stretches wavelegth of photons. - red shifted gravity. hmmm. It gets over my paygrade pretty fast. $\endgroup$ – userLTK Nov 10 '17 at 2:02

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