Can we conceptualise the shape of the universe?
Discussion
The Spruce goose said:
Why is so difficult to know the shape, if such a shape even exists?
We can visualise the shape of three dimensional objects, I think, because we can see them. We cannot see space, so trying to visualise it is just hard.We need to project a three (or more) dimensional space into lower dimension for it to have shape we can visualise. We see the same issue projecting a 3D globe onto paper, it gets distorted, one way or another, depending on the projection technique.
The universe does have a shape, but it boils down to maths and some people can see these shapes in the maths. I can't, but I can kind of see them and visualise them with topological graphs. These potential shapes, more properly called topologies reflect the shape of the entire cosmos. We know gravity deflects space on a smaller scale, but there is a lot of uncertainty at the large scale.
The three main options for the shape of the universe are Open, Closed and flat.
Flat is pretty easy, the universe has no shape on the grand scale and is infinite in all directions. This is also called the steady state universe and now considered unlikely. It makes the universe just too fine tuned for most physicists and means the universe is also infinite in time, there was no big bang.
Closed means it loops back on its self in all directions rather like a sphere in an extra dimension. So a straight line in X, Y or Z will eventually return to its starting point. This is a big bang universe that has finite existence in time. It will eventually collapse into a big crunch.
Open is the most interesting topologically, the universe could literally be any shape, from a doughnut to a corkscrew, or a conch shell. Visualising these shapes requires taking the surface of the shape I named and projecting it into that extra third dimension and is the one I find hardest to grasp. This is a big bang universe but has an infinite future existence in time.
Edited by 4x4Tyke on Wednesday 8th November 17:25
The Spruce goose said:
SantaBarbara said:
What about our neighbouring Universes?
if we can describe neighboring universes, then we would have an idea on the shape of ours, surely? Topologically a universe could be a Coffee cup or a donut, they are the same 'shape'.
https://www.youtube.com/watch?v=4iHjt2Ovqag
https://www.youtube.com/watch?v=4iHjt2Ovqag
The Spruce goose said:
is it possible we as humans could never understand (limitations to visualisation) it where as a computer could?
I think there are some people that could really understand it, but they are rare. Hawkins level intellects and attuned to this sort of thinking. Probably only a handful in the world as a whole.We do have the maths, but don't yet have the measurements to prove things one way or another with any real degree of certainty. There are satellites making the measurements needed to answer the question mathematically and I expect the shape will be resolved in the next decade or so.
Another issue which might well throw a spanner in the works. You'll have heard of the event horizon for a blackhole, the boundary beyond which nothing can escape, not light, not energy or even information. This is why we will never know with absolutely certainty the true nature of a blackhole by observation or experiment. What we do know is determined entirely with maths.
The Universe has the same thing, actually several examples of the same thing, universal event horizons.
One I find intriguing. We know the speed of light is finite, multiply that by time and we have a maximum distance that we can see out into the universe and also into the past. We (humanity or any sentient observer really) will never see the entire universe we are part of. So even our largest telescopes like Hubble have limits, even if we had an array of telescopes right across the Earth, they would still have a limit.
The whole thing is mind blowing really, which makes it so interesting, I'm still a dilettante about this, so you should expect somebody to come along and correct me on bits of this, particularly around the degree of certainty, but the overall picture I've painted should be right.
The Universe has the same thing, actually several examples of the same thing, universal event horizons.
One I find intriguing. We know the speed of light is finite, multiply that by time and we have a maximum distance that we can see out into the universe and also into the past. We (humanity or any sentient observer really) will never see the entire universe we are part of. So even our largest telescopes like Hubble have limits, even if we had an array of telescopes right across the Earth, they would still have a limit.
The whole thing is mind blowing really, which makes it so interesting, I'm still a dilettante about this, so you should expect somebody to come along and correct me on bits of this, particularly around the degree of certainty, but the overall picture I've painted should be right.
Edited by 4x4Tyke on Tuesday 7th November 21:24
Roofless Toothless said:
4x4Tyke said:
I think there are some people that could really understand it, but they are rare. Hawkins level intellects and attuned to this sort of thinking. Probably only a handful in the world as a whole.
Believe me, I do know what a doughnut looks like.4x4Tyke said:
Roofless Toothless said:
4x4Tyke said:
I think there are some people that could really understand it, but they are rare. Hawkins level intellects and attuned to this sort of thinking. Probably only a handful in the world as a whole.
Believe me, I do know what a doughnut looks like.Thing that baffles me is,if the Universe is expanding what is it expanding into ?
Is the Universe creating "space" as it expands ?
Even if it is,then that void into which it expands is a something.
So what is that something?
One theory is that eventually the Universe will stop expanding and will collapse into itself,the "Big Crunch".
I rather like this theory as it provides a cycle,Big Bang,Big Crunch...then when the collapse ends there is another Big Bang.
Problem is what created the first Big Bang ?
Is the Universe creating "space" as it expands ?
Even if it is,then that void into which it expands is a something.
So what is that something?
One theory is that eventually the Universe will stop expanding and will collapse into itself,the "Big Crunch".
I rather like this theory as it provides a cycle,Big Bang,Big Crunch...then when the collapse ends there is another Big Bang.
Problem is what created the first Big Bang ?
avinalarf said:
Thing that baffles me is,if the Universe is expanding what is it expanding into ?
Is the Universe creating "space" as it expands ?
Even if it is,then that void into which it expands is a something.
So what is that something?
One theory is that eventually the Universe will stop expanding and will collapse into itself,the "Big Crunch".
I rather like this theory as it provides a cycle,Big Bang,Big Crunch...then when the collapse ends there is another Big Bang.
Problem is what created the first Big Bang ?
I thought that had been disproved, something to do with the critical density of the universe. If the density of the universe exceeds the critical density, then gravity will eventually slow down the expansion and the universe would collapse back into itself. I don't remember the details, but last thing I read on the subject, the universe's density was below the critical value and was found to be that expected for a 'flat' universe. Is the Universe creating "space" as it expands ?
Even if it is,then that void into which it expands is a something.
So what is that something?
One theory is that eventually the Universe will stop expanding and will collapse into itself,the "Big Crunch".
I rather like this theory as it provides a cycle,Big Bang,Big Crunch...then when the collapse ends there is another Big Bang.
Problem is what created the first Big Bang ?
Also topology is a fascinating subject, things like Mobius strips that can exist in 3D space, but have only a single edge and a single surface. Klein Bottles are similar to Mobius Strips in that they're a 4 dimensional object represented in 3 dimensional space, and again have only one surface, no edges and cannot hold a volume. Things get even weirder in higher dimensions, Strange spheres in higher dimensions.
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