[psychoslave]

It's just that 0.999... is an awful notation, in the sense that it invites people to complete these allusive ellipsis with whatever fit their intuition, possibly even different meaning depending on the context.

If we mean 9×10^-i for i from 1 to infinity, then let's just state so. Let's not blame people to interpret towards other direction when they are provided misguiding hints.

Regarding infinity, there is a constructive proof that it doesn't exists which work perfectly provided that there is an infinite amount of resources allocated to it's execution.

[rachofsunshine]

I don't blame people for finding it counterintuitive. Lots of things in math are counterintuitive. I spent like three months learning Galois theory and I'm still pretty sure someone just snuck in there and changed a 1 to a 0 to make that sorcery work.

My point is that it's not closed-minded of me if I fail to provide a complete answer to someone making such a claim, particularly if that person hasn't done any of the research or rigor to handle what is - by the standards of an expert - a pretty easy question to answer. Outsiders can occasionally result in great insights, but they do that through very hard work, not from ten seconds of thinking about a field they haven't learned anything but the pop-science version of.

Most of the theories being speculated about in this thread are veering into "not even wrong" territory, in that they're not even necessarily well-defined. When you're talking about cosmology you'd better bring your general relativity game, which means you better bring your differential geometry game, which means you better have a graduate-level mathematics education. I have a graduate-level mathematics education and on a good day I could half explain to you what a metric tensor is and what the hell it has to do with curvature ("it's, uh, it's kinda like a Jacobian I guess, except the dx and dy are local vectors that can't be translated globally around the space").

Without those tools, you don't even have meaningful notions of what "distance" even is on a cosmological scale, much less how it changes with time! It's like speculating about biology without knowing what a protein is, or speculating about computer science without knowing what a for loop is. It's just not going to get you anywhere.

[hindsightbias]

Like everywhere else in the intertubes, people think their experience domain is relative to every other specialty domain. We live in a conspiracy world now, where RTFM or "do the work" is a micro aggression.