Space: So far for me it's 3D along with Time T. say 3D+T=4D (spaceTime), from the bigbang we have considered Time (t sub I) as well, considering Time from the start of bigbang to 13.7 Billion years after the bigbang. Since our universe is accelerating due to Dark energy, expansion is speeding up. Now we are inside the universe, what do we call out side of the universe? How can we consider time when we do not have anything to measure in empty space? can we consider time outside the universe when there is nothing to measure or progress (Since Time is a dimension, must tag along always with space, according to special and general theory of relativity). However, What do we call empty space outside our universe say space before taken over by our universe? or what do we call gaps between multiverse ? Further more, what is outside of multiverse (if we think about going as far as we can thinking crazy far). I have just drawn rough diagram here to make you understand what I am trying to say. t sub I is Time at the Bigbang, T-Progress is progress of acceleration of the universe as now. Do not know what happened to Anti matter? can I safely say SpaceTime outside the universe ? Can I move up and down, left and right, forward and back at a point in outside of the universe if it is spaceTime ? How can I understand it ? According to real number line in mathematics, can we consider that space is infinite outside of our universe?