Serifos said:
Thank you very much for your comments. I'm trying to understand them and hopefully I'll get there :-)
For an alternate phrasing of my original question, and to clarify it for a couple more posters that had questions, here's an analogy that hopefully can be a bit clearer about what I'm trying to ask:
In our current everyday and common time scale, if start from some point A in space and travel at human-scale velocity V towards some direction in space (disregard planets, stars or other objects), after some human-scale time T I will arrive at some point B. That point B was there already when I started my travel from point A. Correct?
Well, regions don't just begin to or cease to exist. I'll try to explain how General Relativity describes the universe, and hopefully that will help you to see how this works (I have a hard time just directly answering your question because, well, General Relativity is weird and doesn't necessarily describe the universe the way you'd think).
In strict terms, General Relativity describes the universe as a single, four-dimensional structure, with three dimensions of space and one of time. A useful thing to do to understand this structure, then, is to come up with a way of dividing the universe up into equal-time slices. It turns out that there are many ways of doing this. One way you can do it with our universe is that observers within a given equal-time slice will observe the same time when the average CMB temperature they observe is the same. There are other possible slices (in pedantic terms, an equal-time slice can be made from any space-like surface, and the whole set of equal-time slices is a bunch of space-like surfaces that fill the space and don't overlap). But this is the simplest one when you're trying to describe the expanding universe.
Observers within this structure experience time moving forward, which they see as moving from one equal-time slice to the next. All of the slices are there, but we only experience them one at a time. There's no concept of the individual slices themselves changing because there is no "super-time" which let's it change. It's just a static structure, and time is experienced by moving forward through these equal-time slices.
Then there's the ambiguity of the point "B". Any point in space would be described, with the above system, as a point that moves from one equal-time slice to the next, without ever going backward or traveling faster than light (in pedantic terms, this would be a space-like curve). There are lots and lots of possible curves that go through point B and time T. So, let's imagine you pick one. Every point along that curve is described by General Relativity in a continuous line, with the observer that follows the curve seeing the points on the curve pass one by one (e.g. by watching a clock tick). The whole curve "exists" in a sense, but with different parts of it at different times.
