Originally posted by Fliption
Heusdens, where are you? Did the thread come to a natural end with the participation of Eh and Mentat? It seems you are very much against the idea of a finite space/time whereas Eh thinks it's no uglier then theories of infinity.
I love that this discussion has been coming up more often lately. Carry on.
I have been focusing on here on other issues.
It seemed that my initial thread only lead to the issue of the absurdity of infinity, and not as much about the eternal inflation hypothese. Perhaps we should return back to that theme.
But about infinity...
As a matter of fact I don't think that space/time can be finite.
Although, neither do I think that space/time is infinite in a trivial way (just extending the past to infinity, and extening the observed space to infinity). It happens to be, the universe can not have been this way throughout all of eternity, for several reasons.
Some of this can be explained by Olbers' paradox of the dark night sky. If stars had evolved and were spread around in more or less the same way as they do now, and if space and time were infinite, Olber's paradox proofs that the night sky should be luminous like daytime, because in any direction one would look, we would come across the surface of a star. Naturally, the farther we look, the less brighter and less light we receive, but the more distantiated sphere contains more stars, the two effecst which exactly counterbalance each other (under the conditions that the distribution of lumnious matter is the same throughout all of space and time).
The acceptance of Olbers' paradox leads to the contradiction that either one or both assumptions (space is infinite, time is infinite) are wrong.
A deeper exploration in fact proofs that the night sky IS luminous, and the first calculations of the CMBR showed that this effect of stars from any direction throughout an infine space which was occupied by lumnious matter in the same distribution as we witness now, would lead to a brilliant sky, only not in visible light but as 3K radition.
Current explorations of the CMBR however proof that the spectrum and the fluctuations of the CMBR can not be the effect of star light, and the BB theory provided a better explenation for the CMBR.
Another proof that the universe could not have existed in all of infinity with infinite space, is that the force of gravity would in most cases (dependend on the matter distribution through infinite space) lead to a universe which could not be stable through all of eternity, and thus lead to 'Big Bangs' or 'Big Crunches'.
As a mind experiment, I suggested imagining a universe consisting of only atoms of hydrogen, and assume at some distinct moment a totally perfect distribution of hydrogen atoms throughout all of space. Place an imaginary grid through 3D infinite space (which creates 'cubes' throughout all of space) and place at every corner of a cube (at every crossing of grid lines) one atom of hydrogen, and see how this would evolve through time. Although at first instance this looks like a stable situation (all forces on every hydrogen atom exactly cancel out to zero), but in reality, such can not be the case. All matter would clutter together, only not to a specific point in space, but everywhere. Small inbalances (cause this 'perfect' initial condition, is of course not a situation that is real) would lead to local cluterings, which enlarge themselves.
I am not too familiar with cosmological models, but I have accepted the conclusion of experts, which say that a more or less 'static' universe is impossible.
