Peter Watkins said:
This forum frequently uses the inflation theory to explain or answer various points raised. This would lead one to the conclusion that this theory is largely accepted. This in turn states that contributers believe that the universe was once small. It is now large. There is no possible way that it could have expanded in all directions without divergence. Therefore, an observer viewing from an equatorial site would see a different recession rate from an observer, viewing at the same angle, from the north or south pole, or indeed, anywhere in-between. This, surely, is irrefutable.
If you could explain how expansion could occur without divergence I would be most interested, I'm nothing if not open minded! But please, not the stretched rubber sheet nor the expanding balloon surface. We live neither in, nor on, such a universe.
Peter at this and other cosmo forums in my experience we get a type of obstinate antiscience troll who just wants to argue (based on some popular misconceptions) and not learn. You need to take special care to distinguish yourself from that type of actor. I would suggest you stop arguing for a while and ask questions. Avoid setting up strawmen misconceptions, like the plague.
Your post is full of non-sequiturs.
I for one keep an open mind about inflation. There is no one version you can call
the inflation theory and there are certain other professionally-researched cosmologies that do not require a special episode of inflation at the start of expansion.
But even without inflation (a special type of expansion) the mainstream cosmology does say that the observable part of the universe was once small.
However mainstream cosmology (with or without an episode of inflation) does not say that the universe was once small. In common models the universe has infinite volume today and had infinite volume at the start of expansion.
This in turn states that contributers believe that the universe was once small.
No that is wrong. Your reasoning is faulty. It could have been infinite at the start of expansion.
There is no possible way that it could have expanded in all directions without divergence.
I don't know what you are talking about. The model fits the available data astonishingly well and it predicts approximately uniform expansion in all directions, because of the very nearly uniform distribution of matter. Galaxies are peppered all over so close to even that its fair to estimate the expansion was for all practically purposes even. No preferred directions.
Therefore, an observer viewing from an equatorial site would see a different recession rate from an observer, viewing at the same angle, from the north or south pole, or indeed, anywhere in-between. This, surely, is irrefutable.
This sounds like nonsense. Looking at the cosmos as a whole it has no N or S pole or any equator. And our experience is that expansion is extremely close to uniform in all directions.
Only a tiny correction (typically one percent or less) is needed to account for the solar system's own motion relative to the average bulk of ancient matter. One percent is no big deal.
But please, not the stretched rubber sheet nor the expanding balloon surface. We live neither in, nor on, such a universe.
The expanding balloon surface is a 2D
analogy to one of the more likely ways that 3D space could be. The expanding 3D hypersphere is one of the simplest ways to imagine the universe in the finite volume case. In the case that it was not infinite volume at the time of the big bang, but was, and is now, finite volume, then the most common model people use is the expanding 3D hypersphere.
Since the balloon surface is a straightforward lower dimensional analog of that, it is a useful tool for developing intuitive grasp.
You may be rejecting the 3D hypersphere model without knowing what you are rejecting. It sounds peculiar that you would declare flatly that "we live neither in, or on, such a universe."
It seems to me that the ability to entertain that possibility would be a reasonable prerequisite for participating in constructive discussion at a forum like this. So see if you can wrap your head around it.
One way to imagine would be to first focus on a flat circular disc and think of shrinking the border circle, the boundary, down to a point---as if by a kind of "drawstring". That gives a closed bag, or in other words a balloon surface.
Next you jack your imagination up by one more dimension and instead focus on a round ball with a spherical surface. Analogous to pulling the drawstring in the case of the disk, imagine you can shrink that spherical boundary down to a point. That gives a 3D hypersphere.
Other people may have better analogies and mental imagery to offer, that's what comes to mind for me as an imagination exercise. Anyway, please give it a try and stop saying
"we live neither in, or on, such a universe." Because we might well in fact. It can't be ruled out. At present we don't know whether the real world is the spatial infinite case or the spatial finite case. Both are possible given the data we have so far.
You will forgive, I hope, this obstinate focus on a single (probably futile) effort at communication.
