Why do cosmologists consider the cosmos infinite?

[skippy1729]

Hence, in infinite universe, if God fills it with some stuff - no matter what stuff - at some distance he runs out of distinct configurations and has no choice but to create an exact copy.

Not only an exact copy but also an infinite number of close copies. Including:

Many where I am rotting in a filthy prison as an "enemy of the people".

Many where all women find my charms irresistible.

Many where I am the smartest person in my (local) observable universe, or, dumb as a post.

etc. etc.

Barring any conclusive evidence to the contrary, I believe that I live in a finite universe.

Skippy

 

[shunyadragon]

Lightsphere (after finite time) is always finite when curvature is finite.

The only example when it might become infinite is the final stages of the Big Rip scenario, but there curvature is infinite. Also, Goedel's solution, but it is an oodity as time is cyclical there.

What is your contre-example?

The following a an interesting article that goes into a math model that describes an infinite and eternal universe.

Inflation without a beginning: a null boundary proposal (Dated: February 7, 2008)

by Anthony Aguirre
School of Natural Sciences, Institute for Advanced Study Princeton, New Jersey 08540, USA

and Steven Gratton
Joseph Henry Laboratories, Princeton University, Princeton, New Jersey 08544, USA†


http://arxiv.org/PS_cache/gr-qc/pdf/0301/0301042v2.pdf

The following is the introduction to the article


[cite=[PLAIN]http://arxiv.org/PS_cache/gr-qc/pdf/0301/0301042v2.pdf][/PLAIN]



We develop our recent suggestion that inflation may be made past eternal, so that there is no initial cosmological singularity or “beginning of time”. Inflation with multiple vacua generically approaches a steady-state statistical distribution of regions at these vacua, and our model follows directly from making this distribution hold at all times. We find that this corresponds (at the semi-classical level) to particularly simple cosmological boundary conditions on an infinite null surface near which the spacetime looks de Sitter. The model admits an interesting arrow of time that is well-defined and consistent for all physical observers that can communicate, even while the statistical description of the entire universe admits a symmetry that includes time-reversal. Our model suggests, but does not require, the identification of antipodal points on the manifold. The resulting “elliptic” de Sitter spacetime has interesting classical and quantum properties. The proposal may be generalized to other inflationary potentials, or to boundary conditions that give semi-eternal but non-singular cosmologies.
© source where applicable

[/cite]

 

[shunyadragon]

Not only an exact copy but also an infinite number of close copies. Including:

Many where I am rotting in a filthy prison as an "enemy of the people".

Many where all women find my charms irresistible.

Many where I am the smartest person in my (local) observable universe, or, dumb as a post.

etc. etc.

Barring any conclusive evidence to the contrary, I believe that I live in a finite universe.

Skippy

The universe we live in may very well be finite, than again it may not, but this air ball answer does not address physics and cosmology of the possibilities of greater cosmos containing our universe.

 

[shunyadragon]

Lightsphere of the light, emitted at some moment t, is finite even in cosmology.

One comment . . .

The concept of the nature of our physical existence (containing our universe or being our universe?) is not dependent, nor actually related to the physical attributes of a lightsphere. It is potentially like an infinite eternal matrix irrespective of the material it contains, or possible the potentially infinite and eternal universe as described in the previous reference.

 

[shunyadragon]

I am reviewing to books on Infinity I found interesting.

Infinity by A. W. Moore (1993) is a difficult read and approaches Infinity from a more philosophical agenda. It contains talks and essays from different authors over the last 40 years or so.

Infinity and the Mind by Rudy Rucker (1995) Easier to read and more current in many ways than the Moore compilation. It is well illustrated and more for the well educated general public.

From page 15 to 24 he introduces the concept of spatial infinities, which would be potential infinities as opposed to actual infinities.

I will post more from these two references.