I just come up with the strangest thought while thinking about relativity of time so I want to put it out there n see what comes out from the crowd.
Please be gentle, I am no physicist...
Spacetime is absolute at plank scale what is relative is the comparative length of matter at different speeds between geometry changes as X (in relation to Y) closes up to the speed of light !
Would you say it is true, that the Universe is a set of distinct objects... yes or no?
Could it be defined, using your view (simplified) of the Universe, simply as: objects that are not space and space that is not an object... yes or no i.e. the Universe of the problem has two elements consisting of objects and space?
...in short yes I perceived them as two different (even if connected) objects in the same way energy is clearly distinct of matter although deeply related with it...
I perceived them
You might just as well have asked, once time is just the measure of movement and change, if all things, all chemical and physical reactions came into a full stop, if there is any way so they can start again...but what you are assuming is the absence of active energy anywhere, 100% thermal equilibrium...but again as far as I can tell in the Big Bang there wasn't any 100% thermal equilibrium as the deep space radiation background picture of the event clearly has shown. The maximal degree of order needs not imply a perfect balance. The flow of time, of energy, is more of a prove for precarious balance. The Universe is and works like and engine, but is not a perpetual motion machine, either it came from a Multiverse and will evaporate, in which case, we will need explain the machine Multiverse itself is, and probably without notions of motion, if we truly intend a final outcome without infinite regressions to ever greater degrees of order and Meta-systems, or alternatively the Universe itself and spacetime need be explained resolving the problem of motion so an "engine" can be de-constructed to something else.
More succinctly the million dollar question is, what starts the starter ?...and does it make sense starting a starter ? hmm...it seams evident we need to reframe the problem...
Anyone can see that the past is different from the future. Anyone, that is, but theoretical physicists, whose equations do not seem to distinguish the past from the future. How, then, do physicists understand the "arrow of time" — the fact that the past and future are so different? Leonard Susskind will discuss the paradox of time's arrow and how physicists and cosmologists view it today.