Hi, I had a little amateur debate with my coworker regarding the inflationary theory and I was hoping somebody could clear up a few things for me, since other internet resources only made me confused. First, assuming the expansion happened only to one region of the early Universe, how big did the inflated Universe become? One source shows it became about 1 meter in radius, but it also says the factor of expansion was about 10 the power of 54. Well, that would put the initial size below the Planck's length of 10 to -43, would it not? But then there were no "regions of space", as space-time continuum didn't exist yet, not to mention the fact that we don't have physics to describe anything smaller than Planck's length, as I understand it. So, what gives? Second, how big is our horizon with respect to the inflated Universe? My argument is that the [inflationary] theory is not a result of an observation, it came about as a possible solution to a number of problems with the standard Big Bang model. As such, the magnitude of the expansion needs to be as only big as to sufficiently resolve the horizon, flatness, relics etc. problems, and not a parsec longer. What theoretical necessity would require the size of the inflated universe to be a lot bigger than what we can observe?? But one source says our observable universe is very very tiny compared to the whole inflated universe, which sounds like a rather metaphysical claim to me, and practically unnecessary one, unless it comes as a baggage I have to accept to make the theory consistent. Finally, how credible is all this talk about the scalar field and its decay into what we call our matter. Inflatons?? Is the idea pretty standard in today's scientific community? Also, is there any possibility to infer what happened to the other regions of space within the theoretical framework of inflation? Did they collapse or continue to expand at a normal rate? Are they physically inaccessible due to different laws governing them?? Would there be any way to *empirically* differentiate between any two hypotheses attempting to answer any "parallel universe" question? In advance, thanks for your help or any reference to credible sources. Pavel.