Time is a fable of the mind which fizzles in physics.
Einsteinian spacetime is a philosophical confusion. Unlike electromagnetism, where electricity and magnetism may instantaneously intermingle, spacetime is a conceptual merger without intersection. Einstein himself construed time as reference frames: perceptual perspectives at distinguishable states of a system.
Space and time are entirely different conceptual media. Objects in space move only in the mind via remembrance – a continuity called time which has no per se factual basis. All that ever exists – are sensate – are objects in space extant at a singular present.
Time is entirely within the mind. Yes, objects too are only mental construals, but if you go that far, in blurring actuality with imperceptible mental constructs, you may as well say “everything is everything” and be done with it. Science, mathematics, and philosophy are all studies in distinctions (albeit among conceptual mirages).
Physics states nothing about time. Instead, objects may be mathematically portrayed as having an energetic force instantaneously imposed upon them. Momentum is such a statement: a snapshot in stasis with motion implied by impetus.
Electrons never sit still. Yet, to estimate their mass, these supposedly elemental particles are mathematically put “at rest.” Quantum spin is a relative mathematical characterization to explain observed effects among distinct quanta. Mass and spin are of a moment, outside of time.
Acceleration is a mathematical prediction. That something may happen “in time” connotes an expectation and/or recall which is distinct from time itself.
Immaterial bosons are fundamentally signified by their freedom from time, in that they readily fail the test of continuity. Lacking mass, photons are imagined particles. All we ever see of them is light, which can only suddenly emanate but never be contained, and which has an effect which can instantaneously vanish, leaving behind, at most, only an energetic resonance upon a victim of encountered matter, which may be vented by movement in time. Other bosons are similar in being energetic forces which can only be expressed in objects (fermions: material quanta) at points in time.
Spokes 1: The Science of Existence further explores the physics of time.