Space is not empty.
Space is full of energy in continuous motion.
The continuous motion of spatial energy is called time.
Time, Space & Reality are the three dimensions of a metaphysical universe.
Reality is relative to the time in which space exists.
Space is the energy that forms a present time into a reality.
Space is the energy, time is the motion of spatial energy and reality is the matter realised from energy in a specific space & time.
From a purely physical perspective only matter matters.
From a metaphysical perspective: Space, Time & Reality are all relative to each other.
They are three dimensions of the same universe experienced from different viewpoints.