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After reading Does the universe have a center? and trying to find a place in my mind for "There exists no center", I asked myself:

If there is no center, in what direction our universe will collapse, as soon that time has come? Does this mean the collapse will happen in an instant everywhere?

And if not so, couldn't we say, the center is that point where the collapse finishes(Even if we couldn't determine where this will be)?

ps.: While writing this I made a scene in my had where a spherical object is expanding in every direktion without adding any matter to it and without the posibillity to describe anything outside the sphere. When this spehre now starts collapsing without destroying any matter the same way it didn't create any (thats the actual concept of our universe, isn't it) then everything will get closer to a specific point if observed from "outside the box". But inside the sphere you will just notice that everything is reduicng its distance to everything else without beeing able to notice a specific point this things are moving to as this "point" would be a coordinate of a higher dimension.

Is this more or less the answer to my problem?

Or would there be such a point even from inside, but we just can't determine it by any mean?

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Zaibis
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Sticking with the sphere analogy, first remember that in this analogy, the Universe is a shell, i.e. only the points on the surface of the sphere exist in the Universe, not points inside or outside. If the Universe has a spherical geometry, then the centre would be the centre of this sphere, which is not in the Universe anymore (which is why one would say the Universe has no centre, defined as the point where the big bang happened.) This is the point where it would collapse to, if it ever did.

It is more likely, however, that the centre of the Universe is everywhere. This is consistent with a critical density Universe with flat geometry (which is what most cosmologist believe our Universe to be). In this scenario, the centre of the Universe expanded, but not into a sphere, rather into a flat shape, and thus the centre of the Universe is everywhere. In this case, the Universe will never collapse, but will stop expanding as time goes to infinity.

For completeness I'll add that for a negative curvature hyperbolic Universe, the centre would also not be in the Universe. I think it's fascinating that whatever our Universe turns out to be (though strong evidence for flat), the Universe will either be everywhere or nowhere in the Universe.

Geometry of the Universe

[image: http://abyss.uoregon.edu/~js/images/universe_geometry.gif ]

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