Tom, I thought you were gone forever, i was so worried *hugs*
I'm not gone. I've just been busy with life lately.
Forever means all eternity. Unending. Compared to a number line, this is a function of infinity, not an infinitesimal.
I'm speaking of "forever" as in length, height, and depth. Not time. Inflation theory goes that at the moment of the Big Bang space grew into infinite depth, length, and height, and that it was able to do this in a short finite amount of time. Infinite space literally popped into existence in the moments of the Big Bang.
It does not necessarily take forever to expand infinitely because time is not quantized according to GR. Time cannot be broken into distinct indivisible chunks. Since time is infinitely indivisible, the cosmic geometric progression and expansion of the universe at the moment of the big bang can be nearly instant, filling the universe infinitely in a finite amount of time.
There are some theories in Quantum Mechanics which hypothesize a finite unit of time called the Quanta, but the existence of the Quanta is dubious at best and is in direct contradiction to General and Special Relativity, since they predict a continuous flowing nature of time which can be compressed or stretched infinitely depending on frames of references. The quantization of time is actually one of the big hold-ups in finding a Grand Unified Theory which ties QM and GR together.
I'm also under the impression that the general consensus was that the universe is finite and simply curved extra dimensionally. Not to mention growing faster and faster right now
I'm just pointing out that the theory taught in schools is that inflation expanded infinitely in a finite amount of time. You're talking about the expanding space/dark energy theory, which started sometime after the Big Bang, and is completely separate from Inflation Theory. They are not one in the same. They are supposed to have separate causes and separate mechanisms.
How can space expand when it is already infinite? Well, there are also
different kinds of infinities, where infinite number sets can continue to grow at higher levels. GR predicts a variable continuous universe where a unit of space can be stretched or compressed while remaining as that measured unit.