There are three possible futures for our Universe. One is open, where the universe continues to expand forever. Another possibility is closed, where the universe will eventually stop expanding, turn around and collapse in on itself. The third possibility is really a special case of the first, the universe continues to expand but at ever slower speeds approaching zero velocity.
Spatial dimensions do not exist. The universe in the final state is a single
spinor.
The universe is a multidimensional, ever changing, unfathomably large expanse encompassing innumerable galaxies. I chose the option "other" due to the fact that it is ever changing and will continue to do so long beyond our nanosecond of existence in the grand scheme of things.
Before answer the question “Is the universe Open, Closed, or Flat?” Let’s try to understand “the curvature of universe” (which was used for universe classification)first; otherwise we are not so sure what the question and the answer are!
Start with “closed universe”, which is the universe with positive curvature and was called by mainstreamphysicists as one model of “hyphersurface”. It was explained by analogy that it is resemble to the curve surface of an expanding balloon but with one more spatial dimensions (beside one time dimension). And this hypersurface was born with huge expense that no one could understand how the 3-D surface is curved to be a closed universe! (Please see the topic “Now we could see how space-time is curved!” in the Toe forum “Evolution of the universe”.)
Now for people like us, it seems hopeless to understand the complicated universe mentioned.Thing even worst if we try to visualize “open universe” (negative curvature) which was explained to be the 3-D curve surface resemble to the saddle shape, or “flat universe” (zero curvature) which was explained to be the 3-D flat surface of infinite extend shape. So what we have to do first is try to understand the universe in the sense of armature cosmologists like us (not as the professional one).
We have learn from basic physics course that our universe is composed of all the existing matter such as galaxies, stars, rocks, gas clouds, etc. These matters are attracted each other by gravity and forming as a huge sphere which we called it as our universe. In this sense, it is not so difficult to understand the universe we lived. And it is interesting to note that how this simple universe turn to be an unimaginable universe by experts!
For my opinion “something” must be overlook, something which is the foundation of everything in the universe! And indeed we can prove that there is an unseen “vacuum medium” which is the fabric structure of our universe with the property that resemble to the old familiar aether. [Detail with simple explanation in scientific way was shown in “Completed Einstein general theory of relativity (CGTR)”, which is presenting in www.vacuum-mechanics.com.] Once we have something to deal with, then it is easy to visualize the models of our universe.
Now let’s see the closed universe model by analogy, it is something like the earth’s atmosphere. When a light ray is passing through, it will bend around the earth and would finally form a closing path (if the atmosphere is big enough). The reason is because of the non-uniform density of the atmosphere which is decreasing when increasing the altitude. This is the meaning of closed universe (of the atmosphere) with positive curvature.
In the same way we could visualize the understandable model ofuniverse as the huge expanding spherical sea of unseen vacuum medium with all galaxies, stars, rocks and gas clouds whirling around. If the average density of vacuum medium (including all of the existing matter) is uniform through out the sphere, then it is flat universe with zero curvature. Instead, if the density is higher near the center than the rim then it is closed universe. And in the reverse, if the density is higher near the rim than the center then it is open universe.
Finally, based on the existence of vacuum medium, when working out in detail we would found that our universe is closed. And it is interesting to note that this answer is opposite to the present result (which was worked out by using the conventional theory of Einstein general relativity), isn’t it?
I think the universe is finite in space but unbounded in time.
__________________ (George Berkeley, 1710) ... lay the beginning in a distinct explication of what is meant by thing, reality, existence: for in vain shall we dispute concerning the real existence of things, or pretend to any knowledge thereof, so long as we have not fixed the meaning of those words.
"All things come out of the one and the one out of all things." - Heraclitus "Reality is an illusion - albeit a persistent one." - Einstein "Particles give me a headache." - Ibid
A Multiverse or Universe(s) is not one of the options. I could only blindly speculate on what that might mean for expansion's end. Does anyone have any good ideas on the shape of a Multiverse??
Spiral shaped?
"Finite (in space) but unbounded (in time)?
Regards,
-RP
__________________ (George Berkeley, 1710) ... lay the beginning in a distinct explication of what is meant by thing, reality, existence: for in vain shall we dispute concerning the real existence of things, or pretend to any knowledge thereof, so long as we have not fixed the meaning of those words.
"All things come out of the one and the one out of all things." - Heraclitus "Reality is an illusion - albeit a persistent one." - Einstein "Particles give me a headache." - Ibid
It was claimed from NASA (via Encyclopedia Wikipedia) that Wilkinson Microwave Anisotropy Probe (WMAP) gives the confirmation of the standard flat Lamda-CDM model.
But also in “Cold dark matter (CDM)” of Wikipedia say that the one serious problem of CDM theory is that we don’t know what really the cold dark matter is!
Thanks for the information Nimit Th. Does that mean the jury is still out regarding the universe being open, closed or flat, until they determine what dark matter and/or dark energy is?
Thanks for the information Nimit Th. Does that mean the jury is still out regarding the universe being open, closed or flat, until they determine what dark matter and/or dark energy is?
Pat
Dear Profpat and friends,
It is nice to talk to you.
It depends on one’s opinion! For me I think that it should, it would give us more confidence.
As I know, Lamda-CDM theory has assumed that first the universe is flat and then trying to find the Lamda which tell how many percent of CDM is existed. Is it right? If it is, then in order to keep the expanding of the universe for the flat model, the CDM has to increase indefinitely! This seems crazy and it is for this reason that we have to know what CDM is, isn’t it?
Re: Is the Universe Open, Closed, or Flat? 
Linear Mode
