What does it mean to extrapolate back in time and to reason about mass and space, when all of those were “coming to be” during the “time” we are trying to reason about?
Do we assume that “time” existed “before” the “big bang?” Why?
If time is not truly linear (but linear time is just a function of human perception) then there may be different questions that are more appropriate.
One theory of time is that it is like a reel of film.
If your run the reel forward at normal viewing speed you have human perception.
Needless to say that is not the only possible way a reel of film could be viewed.