Einstein’s General Theory of Relativity construes space and time as the dimensions of the universe: space-time is the frame of reference, a four-dimensional grid, in which events occur.[1] This is quite different from everyday speech, where ‘space’ is often used to refer to the absence of visible matter (in space-time), and ‘time’ is often used to refer to processes or events (in space-time), as when linear processes or cyclical processes are referred to as ‘linear time’ or ‘cyclical time’, respectively, or when sequences of events are referred to as the ‘flow of time’.[2] The crucial difference, in terms of the present discussion, is this: the everyday usage construes space and time as phenomena that are experienced, whereas Relativity construes space-time as the frame of reference in which phenomena are experienced. Time and space are construed as the reference system against which events are measured, events that include the categorising processes of experiencing organisms.
Footnotes:
[1] According to the Uncertainty Principle of Quantum Physics, it is not possible to measure both the momentum (mass x velocity) and the position of a particle. Momentum can be construed as a measurement with regard to matter-energy, while position can be construed as a measurement with regard to space-time, the frame of reference. A quantum matter-energy field (of difference) conforms to the wave model as a measure of momentum (relative to other matter-energy), and to the particle model as a measure of position (relative to space-time).
[2] To say that the universe — in some sense — “already exists” from the big bang to its heat death is to confuse time (as a dimension) with the unfolding of events.