# Does the universe have a centre? **URL:** \ **Category:** Factual Questions\ **Created:** [April 16, 2002, 8:22pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007 "2002-04-16T20:22:15Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![Quintas](https://avatars.discourse-cdn.com/v4/letter/q/48db29/32.png) [@Quintas](https://boards.straightdope.com/u/Quintas)\ **Post date:** [April 17, 2002, 2:33pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/21 "2002-04-17T14:33:34Z")
Someone tell me if I have this wrong. Isn’t there indeed a ‘center’, it just happens to exist in a 4th physical dimension? The way i’ve heard it explained, it’s like a 2D creature who exists on the surface of a balloon. Their world would be finite but with no boundaries or ‘edge’. If these 2D creatures could move thru the 3rd physical dimension they would find the center inside the balloon. We exist in a 3D universe that curves thru a 4th dimension so in order to find the center we would have to have the capability to move thru a 4th dimension. I realise that sometimes time is referred to as a 4th dimension, but im referring to a 4th physical dimension, so perhaps it should be called the 5th dimension or something. ---
**Author:** ![FriendRob](https://avatars.discourse-cdn.com/v4/letter/f/ecc23a/32.png) [@FriendRob](https://boards.straightdope.com/u/FriendRob)\ **Post date:** [April 17, 2002, 2:50pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/22 "2002-04-17T14:50:56Z")
**Quintas** : This is something else that’s hard to picture. A curved space (think balloon) can be _embedded_ in a flat higher dimensional space (think your room, ie. regular old 3-D space). But mathematically, the embedding space is unneccessary: anything that goes on on the (2-D) surface of the balloon can be described _without referring to the (3-D) embedding space_. If we lived in 2-D we could postulate that the 3-D space existed, or we could be content with a curved 2-D space. Here’s the rub: \* There’s no way to tell the difference!\* So we can’t tell if our curved 4-D spacetime is “really” inside of a higher dimensional space, or if it’s merely a curved 4-D spacetime. No way to tell (measure) the difference means it’s not an interesting question to physicists. Philosophers may argue at will for either proposition. BTW I think you need at most twice the number of dimensions for the embedding space (or maybe 2D-2?). So our 4-D spacetime lives inside a flat 8-dimensional space. Or maybe it doesn’t. ---
**Author:** ![Mersavets](https://avatars.discourse-cdn.com/v4/letter/m/aca169/32.png) [@Mersavets](https://boards.straightdope.com/u/Mersavets)\ **Post date:** [April 17, 2002, 3:38pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/23 "2002-04-17T15:38:04Z")
I understand it is pointless to consider an outside of the Universe, but what about the boundary? What, if anything, differentiates the boundary from the content other than that it is the edge of the content? Is space created by the matter moving out or is there space created in front of the matter for it to move into? What would an observer see near this boundary? If the expansion were less than the speed of light, it should be possible to see to the boundary, no? ---
**Author:** ![bryanmcc](https://avatars.discourse-cdn.com/v4/letter/b/eada6e/32.png) [@bryanmcc](https://boards.straightdope.com/u/bryanmcc)\ **Post date:** [April 17, 2002, 3:45pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/24 "2002-04-17T15:45:29Z")
There is no boundary. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [April 17, 2002, 4:04pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/25 "2002-04-17T16:04:04Z")
There can be no boundry, a boundry is between two things. The universe is everything, there is nothing else, therefore there is no boundry. New space isn’t created “at the edge”. It is created everywhere. Again, consider the analogy of a balloon expanding, where does the extra surface area come from? It is created everywhere on the surface, simultaniously. ---
**Author:** ![Stinky](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@Stinky](https://boards.straightdope.com/u/Stinky)\ **Post date:** [April 17, 2002, 4:35pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/26 "2002-04-17T16:35:41Z")
> [@](#): > > Cosmology is without a doubt the most confusing and maddening discipline I have ever read about. All Cosmologists should be locked away and absolutely prevented from interacting with normal humans. Try Quantum Mechanics it makes Cosmology seem simple. > [@](#): > > I guess it also follows that I still can’t understand the universe expanding. Oh, I get the analogies alright, I just don’t get why it would be expanding. Well if that cooks your noodle,just consider that not only is the Universe expanding, it’s accelerateing. > [@](#): > > The biggest problem with the balloon analogy is that it implies that the Universe is spherical, or rather hyperspherical. While that’s one of the standard possibilities for the large-scale geometry of the Universe, it’s not the only one, and in fact, recent measurements seem to indicate that it’s flat. No matter how far you go, or how big your visual radius, you don’t necessarily wrap around. That’s why I like the rasin bread analogy : Concider that the rasins are the mass in the Universe and that the dough is space. As the dough rises (time) all the rasins move away from each other. > [@](#): > > Latest reasearch has shown my belly button to be the center of the Universe. It is open to the public weekdays from 9 to 5 and at other times by appointment. No smoking, food or drink please. Sailor you crack me up. > [@](#): > > I understand it is pointless to consider an outside of the Universe, but what about the boundary? What, if anything, differentiates the boundary from the content other than that it is the edge of the content? Is space created by the matter moving out or is there space created in front of the matter for it to move into? What would an observer see near this boundary? If the expansion were less than the speed of light, it should be possible to see to the boundary, no? There is no boundary everything is at the center in its own frame of reference. ---
**Author:** ![smaft](https://avatars.discourse-cdn.com/v4/letter/s/c2a13f/32.png) [@smaft](https://boards.straightdope.com/u/smaft)\ **Post date:** [April 17, 2002, 7:11pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/27 "2002-04-17T19:11:30Z")
> [@](#): > > \*Originally posted by waterj2 \* > Well, in downtown Boston, near the entrance to Filene’s, there’s a large plaque embedded in the ground denoting that exact spot as the Hub of the Universe. No, no, no. The center of the universe is in Seattle’s [Fremont](http://www.seattlephotographs.com/photos/fremont/fremont_sign_2d.htm) district. Plus, the [troll](http://www.roadsideamerica.com/attract/WASEAtroll.html) is there. What more proof do you need? ---
**Author:** ![don\_willard](https://avatars.discourse-cdn.com/v4/letter/d/a88e57/32.png) [@don\_willard](https://boards.straightdope.com/u/don_willard)\ **Post date:** [April 17, 2002, 7:52pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/28 "2002-04-17T19:52:35Z")
What about if the universe was expanding into the Bessicovich-Hausdorff Dimension or a dimension between the other dimensions? Also, everyone is saying there was nothing before the big bang of the universe, but I heard that there was a quantum fluctuation field (of energy?) and it fluctuated and made the big bang . Also, there is the theory that this quantum field fluctuates and makes the universe and then the universe spreads out so that it gets so thin of matter that it causes the quantum energy field to fluctuate again and precipitates the next universe. Or when things get too spread out there is such a strain in the universe that it reacts by fluctuationing new material. The quantum energy field causes the dimensions to come into place, along with space and energy, while time is just a succession of these events. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 17, 2002, 8:02pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/29 "2002-04-17T20:02:52Z")
There is only one flat geometry: Flat. There are, however, several flat topologies. The plane, the (flat) torus, and the cylinder are three examples, but there’s also the cone, the twisted torus, the Klein bottle, and probably a few others that I can’t think of at the moment. Of course, these are all just 2-d, but there are similar examples for higher dimensions. There is a simple N-dimensional generalization for the flat torus: Instead of a rectangle where each side maps to the opposite side, just think of a rectangular prism where opposite faces map, or a hyperprism, etc. There is also a similar variety of topologies for non-flat spaces, but they’re rather more difficult to envision. Quoth **FriendRob** : > [@](#): > > BTW I think you need at most twice the number of dimensions for the embedding space (or maybe 2D-2?). So our 4-D spacetime lives inside a flat 8-dimensional space. Or maybe it doesn’t. Not necessarily. A flat space can, of course, be embedded in another flat space of the same dimensionality (you can fit a piece of paper on another piece of paper). Some curvatures can be embedded into a flat space of dimension only one higher (any N-sphere can be embedded into only N+1 dimensions, for instance). I’m not sure what minimum dimensionality an embedding space must be to contain an arbitrarily-curved N-dimensional space, but it’s not really relevant, anyway: The only real use for embeddings is as an aid to visualization, and that’s hard to do anyway when the embedding space is higher than 3-dimensional. Usually, when you see an embedding diagram for, say, a black hole, you use the symmetries of the system to reduce your dimensionality to the point that you can embed it in 3-d space. ---
**Author:** ![Homer](https://avatars.discourse-cdn.com/v4/letter/h/df788c/32.png) [@Homer](https://boards.straightdope.com/u/Homer)\ **Post date:** [April 17, 2002, 8:21pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/30 "2002-04-17T20:21:18Z")
Chronos, I’m almost disappointed that you didn’t refer Sue’s “what came before” questions to the [theory of branes](http://www.sciencenews.org/20010922/bob9.asp). The idea is, the intersection of these branes are what sparked the “big bang” and that their eventual pulling apart again will lead to the “big collapse” which will eventually be followed, again, by a “big bang” as they cross again at some point. It’s like a circle - where does it start, where does it stop? Nowhere, and yet, at the same time, everywhere. It continues. Will the next implosion / explosion cycle lead to _this exact same existence_ again at another point? Will it be entirely different? We don’t know, and we can’t possibly know. How… odd… is it to consider the idea that we may have existed, in this exact same manner, a hundred trillion times before. Perhaps we’ve actually only existed this once, and these hundred trillion other times over an unimaginable span of time are simply reflections and reverberations of our current (or past, or future) existence. Or maybe it’s a string tied in a circle - a big knot at one point, but without any start or stop… can we say then, that we’ve existed more than once? Or is it the same existence repeated? I’m going to go lie down for a while. Tim ---
**Author:** ![bryanmcc](https://avatars.discourse-cdn.com/v4/letter/b/eada6e/32.png) [@bryanmcc](https://boards.straightdope.com/u/bryanmcc)\ **Post date:** [April 17, 2002, 8:34pm UTC](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007/31 "2002-04-17T20:34:02Z")
> [@](#): > > \*Originally posted by Chronos \* > **There is a simple N-dimensional generalization for the flat torus: Instead of a rectangle where each side maps to the opposite side, just think of a rectangular prism where opposite faces map, or a hyperprism, etc.** Duh. Now that you state it, it’s perfectly obvious. Don’t I feel silly. For some reason I was trying to visualize a non-flat torus (donut) into N-space. -b [Previous page](https://boards.straightdope.com/t/does-the-universe-have-a-centre/104007.md?page=1)