I'm not quite sure how to ask this so that it can be answered in layman's terms, but I have lately seen, in several places, that with cosmological inflation, there was a point where the universe expanded faster than the speed of light.
In this explanation, the following is stated:
- Gravity itself would have split off at the Planck time, 1e-43 of a second
- The strong nuclear force by about 1e-35 of a second
- Within about 1e-32 of a second, the scalar fields would have done their work, doubling the size of the Universe at least once every 1e-34 of a second (some versions of inflation suggest even more rapid expansion than this).
It goes on to say that this rapid expansion is enough to take a quantum fluctuation 1e-20 times smaller than a proton and inflate it to a sphere about 10 cm across in about 15 x 1e-33 seconds.
The conclusion is that this expansion occurred at faster than light speed.
My main question is about the role of time in all of this, and I'm only indirectly interested in this apparent violation of the cosmic speed limit.
I have watched at least one interview (and I can't find a link to it right now) where a well-known physicist sums up the meaning of time as a big unknown, not being intuitively "fundamental" the way space is. However, in the very least, and perhaps most abstract way, time is an important part to the mathematics when it comes to explaining how things work.
My own understanding of time is that it is a way of gauging change relative to some known standard that is changing. (And acknowledging that it can change, depending on one's frame of reference.) That standard might be the swinging of a pendulum or the oscillations of some subatomic particle.
But in the earliest part of the universe's lifetime, before and during inflation, what was the standard for measuring time? Why would it be acceptable to say that the time duration of the inflationary period was so short and thus violated an accepted principle. Couldn't an alternative view be that the inflationary period lasted longer and nothing travelled faster than the speed of light? How was it decided that the duration of time for the inflationary period was so short?