I would like to understand more about time. I am studying amongst other things, reality. If BB theory is the standard explanation for the start of everything then I would like to know how it explains the start of time. We link time to space and to events (entropy) and we measure time in defined units related to changes in the energy level of the caesium atom. Seems clear to me what time is. I don’t understand what is meant by claims that time is an illusion. BB theory says that time started with the existence of the singularity. I think it has to, otherwise we don’t get any BB sequence flow. Space also has to exist, otherwise there isn’t any expansion. If the singularity was a one-time event, how did information flow in the first fraction of a second in order to feed the expansion? In one place I read, it is ascribed to negative gravity and in another place it is ascribed to a vacuum effect i.e. the expansion was a sucking process rather than a pushing process. In this version, what did the sucking? Or if it was a pushing process using dark energy, how does dark energy push? Taking the negative gravity version, if in a high density, high mass environment gravity slows time down and presumably negative gravity speeds it up, was this factored into the BB timeline calculations? Am I correct in understanding that if the universe was initially highly compressed, time would hardly flow due to high gravity. Then with the reversal of gravity, time would suddenly speed up tremendously, hence the very high rate of initial expansion? Is this what is meant? BB theory uses such tiny fractions of a second after the BB, I start to wonder what meaning do such time calculations have? Alternatively, is it necessary that the BB proceeded so quickly? If it was neither Big nor a Bang, is it also possible that it proceeded extremely slowly? Have we got the wrong title here? So my question is, at what point in the history of the universe did time as we collectively perceive it on earth start? Did it start with the singularity or did it start with the decoupling? Does the inflationary time period (photon epoch) of 380,000 earth years mean anything in terms of time elapsed by today’s time flow standard? Until the photons were free, were they nevertheless travelling at c and how do we calculate the timing of BB events? What am I missing or misunderstanding, which would support the timeline of the BB, especially its very high rate of expansion from a standing start. Could it have been orders of magnitude slower? Please note, I only want to better understand BB theory, I don’t want to criticise it, although I am interested to know if there is more than one accepted BB version concerning the start of time.