Inflation theory has it that the early universe was causally connected, and could “mix”, hence explaining relative homogeneity of the CMB. The universe then rapidly expanded and became causally disconnected as it is now.
Now, when I picture the Big Bang, I picture a coordinate grid appearing out of nowhere, and the universe “expanding” is simply the act of “zooming” into the grid. The grid is obviously infinite in this case, and hence I cannot see why one point can be “causally” connected to another point arbitrarily far from it (since even the early universe was infinite).
To me then, inflation theory seems to assume that the early universe (and the universe as it is now, for that matter) was finite, and hence could be causally connected, before rapidly expanding to the way it is now.
I don’t think my thought process is right here, so it would be appreciated if anyone can correct my misconceptions.
