Is the Universe Flat or Curved?

[phinds]

In other words its not relevant water is water and space is space and it doesn't mater what shape the container is

Actually, it does matter quite a bit. In immediate practical terms, probably more so for a body of water than for space, since the size/shape of the container says a LOT about what you can/cannot DO in that body of water/space. It's tough to get a battleship into a bathtub for example.

Understanding the "shape" of the universe may well lead to understanding of other things of more immediate relevance.

Your point of view seems contemptuous of science.

 

[alt]

The shape and geometry of the universe are ultimately different things. For example, a flat universe could be in the shape of a flat sheet or a donut. What we actually measure with cosmological observations is the intrinsic geometry of the local universe. The best way to distinguish different intrinsic geometries is to consider whether the Euclidean postulates and their consequences hold: for example, in a flat geometry, the interior angles of a triangle sum to 180 degrees. In curved geometries, this no longer holds.

OK, thanks. I understand that. So are you saying that to say 'flat universe', one means it in terms of flat geometry, 180 deg triangles, etc ?

 

[bapowell]

OK, thanks. I understand that. So are you saying that to say 'flat universe', one means it in terms of flat geometry, 180 deg triangles, etc ?

Yes, that's exactly right.

 

[neginf]

Does the universe's flatness mean that non Euclidean geometry isn't important in physics?

 

[Essopartes]

I am a bit confused on what the current model of the universe is. some are saying it is round, while others are saying it is flat. which is true?

If the universe is flat, then is it that only some part of it is flat or the whole universe is flat?

how can we prove it theoratically and mathematically?

According to the depicted universe described in special relativity, particulary concerning the Lorentz transformations, the universe is flat with a .08 margin of deviation due to the differentiation between co-motion systems. In a difference of say, a rotational axis, certain points experience alternate rates of fluctuations to compensate for their differing inertial reference frames, specifically, when evaluating that circular system of rotation, when an side undergoes a contraction by:
L₀√1-v²/c²
the radius will grant an invalid conclusion in the description of the area of a circle, namely A=∏r², which is mathematically impossible in the Euclidean geometry of a classical universe, hence the necessitation of a curved space-time.

 

[GeorgeDishman]

Does the universe's flatness mean that non Euclidean geometry isn't important in physics?

It is flat on average over very large scales. Locally it has curvature, we call that gravity and without it the Earth wouldn't orbit the Sun so yes, non-Euclidean geometry remains important.

 

[urodoc]

flat or round, spherical or trumpet - does the universe have a thickness ?
is it centrally thicker like 2 cymbals placed together ? how do we know if it is symmetrical ? is it getting thinner in the centre as it expands peripherally? why should it be symmetrical - was the singularity that preceded the big bang spinning in order to give it such symmetry ?

 

[Mark M]

flat or round, spherical or trumpet - does the universe have a thickness ?
is it centrally thicker like 2 cymbals placed together ? how do we know if it is symmetrical ? is it getting thinner in the centre as it expands peripherally? why should it be symmetrical - was the singularity that preceded the big bang spinning in order to give it such symmetry ?

Urodoc, when people speak of the shape of the universe, they are speaking of a natural curvature that spacetime has over large distances. The universe doesn't have a 'shape' in the literal since, as it has no boundary.

Keep in mind that the expansion of the universe occurs everywhere at once. There is no center or boundary. Also, the universe is symmetrical because it underwent a period called 'inflation' in it's very early history. Inflation was an enormous expansion, of unimaginable magnitudes. It essentially functioned to 'iron out' any inhomogeneities in the early universe.

 

[George Jones]

It is flat on average over very large scales. Locally it has curvature, we call that gravity and without it the Earth wouldn't orbit the Sun so yes, non-Euclidean geometry remains important.

when people speak of the shape of the universe, they are speaking of a natural curvature that spacetime has over large distances.

When people talk about the curvature of the universe, they mean the curvature of space, not the curvature of spacetime. For example, in a flat FRW universe, space is Euclidean and flat, while spacetime is neither flat nor Euclidean.