I think I have an answer, Hadad. Let us assume that something must always have existed (to explain that first singularity for example). But time and space only begin to exist with that singularity that is the universe. Therefore, whatever exists from which that singularity might have come, must exist outside of space and time. I propose that there exists an initial condition that is outside of space and time. We must call this initial condition Z=0 to indicate it exists before the first instant of time.
At the beginning of the Big Bang there is a change, which is the first instant of time, and leads to the singularity that is the first expansion of space from zero to one. We can now identify the singularity as Z=1 and the change from the initial condition to the singularity as the change/time T=1.
Now lets draw this out...
Z=0 >---(T=1)---> Z=1 >---(T=2...n)---> Z=2...n
Z=0 therefore exists before time (beginning at T=1) and space (beginning at Z=1). The properties of Z=0 cannot be properties of either space or time. It can have neither size nor shape, neither location nor motion, neither inside nor outside, etc. It can have no beginning nor end, nor may it ever change. Because it can have no beginning or end, it must either exist without possibility of non-existence or it must not exist without possibility of existence. Of course, if it didn't exist, I could not have written this nor could you read it; for we would not exist, our universe itself would not exist.
One property that Z=0 could and indeed must have is potential. It must have the potential of our entire universe, else the universe could not arise from it. In what manner that potential may exist I cannot say, but THAT it exists I am certain. What if we distribute all that potential across the "infinity" of space and time? Then we have a universe, do we not?
What do you think?
Mass and energy are equivalent, as per Einstein's equation, but mass--whatever that is--cannot be accelerated to light speed.