As T Clark suggests, we should acknowledge proven undisputed evidence, and then distinguish it from theory and speculation. All are fine so long as we recognise what each element represents.
Science is confident about the minimum size of the universe today in absolute terms. It is also confident about what the speed of light can achieve in normal circumstances today. Clearly the maths which T Clark pointed out is self explanatory if you believe in the Big Bang. The universe
must, in
absolute terms, have expanded faster than the recognised maximum speed of light.
As I have pointed out in other threads, the principle that 'the speed of light was the maximum that could ever be achieved',
was and remains speculation. It's not been a bad supposition for our limited circumstances and for our development of such things as atomic energy, but that doesn't have to extend to the cosmos.
When the evidence clearly says that, in certain conditions, it
must be possible to travel faster than the speed of light in absolute terms, then we are fools to ignore it.
Indeed, in this respect, relativity is open to too many variables to provide a comment on this - when by its nature, any 'absolute factor' must take precedence over relative readings. The width of the universe is such an absolute - and a figure that wasn't available to Einstein.
The inflation of space was a notion dreamt up purely to preserve the notion of a fixed value for the speed of light as currently measured. It has no evidence to support it and only exists to preserve doctrine over substance.
The conversations on this thread have also blurred a number of other factors.
There is a difference between:- material moving outwards; a shock wave; and space itself expanding.
I feel that in normal language, suggestions of a shock wave
would need some medium in which to generate the wave, (as others have suggested). You may argue that Dark Energy might constitute that wave, but Dark Energy is just theory and has no physical evidence to support it either. So it may not be correct - and I give an example of a simple alternate theory below.
However, for the moment, I'd like to set the context for all potential explanations. The 9 year results of the WMAP programme clearly stated that the dimensional lines run straight and are not bent as far as we can tell. Therefore by implication, they run to infinity and so space itself may genuinely be infinite.
Whether that means that space is 'something' rather than emptiness is hard to fathom. Finipolscie speculated that space may represent the framework for existence - quite apart from any material or energy that might occupy it.
His logic was along the following lines :-
If you were on the leading edge of the expanding material from the Big Bang and could see a location ahead of you which you can identify and move towards, then that space must exist in some form. He also pointed out various ideas that say there are a small number of core factors in existence which shape everything else. I think he said there were 6 - which he likened to settings on the 'control panel which governed the rules of existence'.
I have found other authors who make the same point. There 6 parameters, and each of them could, theoretically, have had any of a whole range of settings - each potentially resulting in very different manifestations of the universe..... but why they settled on the settings that they did, is unknown.
However we are also unsure of what makes existence
conform to those settings, and therefore we speculate about a framework for existence, although we don't know how it might be imposed. It is this which suggests that space may be more than simply 'location' - and not just the material or unidentified Dark Energy which may occupy it.
The idea of Dark Energy was entirely driven by the finding that the redshift was increasing - from which people assumed that the expansion was accelerating. However, there is no need for Dark Energy if the original Bang-Crunch model of the universe is applied fully.
Think about it. The increasing redshift could just mean that we have entered the crunch part of the cycle in which case, Gravity would be causing that acceleration - there would be no need for Dark Energy.