Originally Posted By: Finiter
If the internal energies of the bodies are proportional to their speeds, ie, the speed-internal energy is same for all at any given time, then the expansion can be regarded as a thermodynamic change involving speed and internal energy. that is there is no need of an explosion.

It is not uncommon for physicists to argue that we should not regard the BB as an explosion, because it is an expansion of everything, rather than a situation in which the Universe is being forced out into pre-existing space. Although I appreciate this line of reasoning, I feel that, in terms of the physical scenario, it is little more than an exercise in semantics. Your distinction appears to be similar. Is an explosion not an expansion brought about by thermodynamic change?
There never was nothing.