And a flat universe would not really be infinite.
Flatness means at least a spatial imit. A spatial limit is probably connected with a temporal limit. A temporal limit is not infinite.
I suspect the question shouldn’t be “Why is the universe flat?” but rather, “Why does the universe appear flat?”
And I suspect the answer involves the rotation of the Milky Way galaxy.
Do you mean our galaxy, Socratus? 
I know that the mainstream physicists say our universe would be flat, very flat. But it is probably not flat. Are the mainstream physicists flat?
Flatness as a spatial limit is connected with geometrical forms:
triangle, square, . . . circle, . . . . .
Flatness as an infinite continuum is connected with negative
Pseudo-Euclidian space (Mincowski - SRT)
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It is amazing and depressing how dim and stupid, bright and intelligent people can be, as displayed below:
[youtube]http://www.youtube.com/watch?v=veU6hK3jMH4[/youtube]
[youtube]http://www.youtube.com/watch?v=1jY5BjGADv4[/youtube]
How can such brilliant people be so dim? 
It is certainly no coincidence that two similar beliefs occured and became dogmas at the same time: (1) the belief that the big bank can create the money out of nothing; (2) the bielef that the big bang can create the universe out of nothing. 
When the Big Bank goes Bust, does that create a new universe/economy?
According to those who believe in that: … yes.
I guess that would support the notion of an eternal re-occurrence rather than a “something from nothing”. There had to be people before there could be money. 
But yeah, both BBs require deception.
Maybe an eternal re-occurrence of something from nothing, but always created by the respective bb.
Yes eternal, but not an exact recurrence. The idea of identity having been surpassed by similarity by unperceptible differences, gives reign to a process of I change. Eternity could not be measured or fathomed by identical recurrences, it would defeat change, in fact it would result to a frozen, immutable state.
The mathematics proves that identical re-occurance/repetition is impossible. When I said re-occurance, I was referring merely to repeated “bangs”, not repeated identical results.
No doubt in reality, the galaxies become black holes that collide such as to reproduce new galaxies that do the same all throughout the infinite universe.
GRT is theory of limited / local masses (sun, stars . . .)
in the infinite negative 2D
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In the realm of a logical super cession of language systems, such as mathematics, the idea of identity,as
In the case of Liebnitz’s two identical spheres, seems to rule in favor of absolute causes. Where similarity and not identity is the progenitor of language, (as Wittgenstein points to in his 'family of resemblances); shadows the idea of Leibnit’s functional derivative in a sequence set of diminishing value, where 1 does not equal .00000000000000009. This we discussed before. But at the virtual point where this can only be described in hyper-real
numbers, an absolute identity has to be supposed.
At that point, something happens in the conscious transformation, or reversely, in the reflexive modus operandi, where the cognitive virtual world of supposed absolute identity ,implicates a relative(in the sense of relational) between this absolute, and the relative, or relational , categorically defined mathematical subset. (Inference, or logic)
So it becomes necessary, by logical inference that such process is understood as such: and even if, black holes are only cognitive tools to apply to the most probable event, the probability is such, as to ground the mathematical description of it, as the most probable course to define what is happening.
Identical bangs, given a progression of similar occurances toward the infinite reps, reduce the conceptual differential values, toward the imperceptible, therefore gaining an identically repeating universe a conceptual ‘sameness’.
But to be defined as same, that universe has to be compared to -same as what- and in that sense it has to be the same as the identifiable other sphere.
But that develops into other unidentifiable spheres, giving rise to the worlds of bubbles, each appearing the same as the other.
The idea of the eternal recurrence, as exact copies, is at the least, becomes necessary, in order to base a logical foundation to mathematical and semantic languages.
Mathematically, it turns out to be more than infinitely improbable that given an infinity of time, the universe would ever become even remotely similar in shapes and positions to any past that it had ever been. The reason is that it has 3 dimensions of freedom in spatial positioning yet only 1 dimension in time. If the universe was only one dimensional, there could be a finite possibility of the universe repeating itself at least once throughout infinite time.