There Is No Time.

"Spacetime" is a misnomer. Time is not a property or a dimension of space. It is merely a concept, an organizing principle invented by humans to track sequentiality and assist in the prediction of certain regular movements and events. As a concept, of course, it is indispensible! As a supposed component of physical reality, it's a phantasm.

Relativistic effects such as time dilation (where time is said to "slow down" at extreme velocities) are nothing more than the observable, physical effects of velocity upon matter. Time does not slow down: matter does. As a mass is accelerated to relativistic (very high) speeds, the physical processes within that mass slow down. Right down to the subatomic level. Everything decelerates, from gross mechanical processes such as the ticking of a Swiss watch, to biological processes like neurons firing in someone's cerebral network, to invisibly minute processes such as the oscillation of electrons in their atomic orbits. Time is simply how we measure things like objects crossing distances, or the resonance frequencies used by an atomic clock. If something slows all of these processes down, we perceive and describe it as time dilation - "time slowing down."

It's a harmless enough way to put it, from a purely conceptual standpoint, but it is rather putting the cart before the horse! Because as convincing as the illusion is, it's nothing to do with forces "acting upon" time. The slowdown is a simple property of velocity acting upon matter - a fundamental, easily-observed and easily-understood interaction, and one that cries out for no mysterious, mystical entity such as "Time" to explain it.

Even experiments whereby physicists claim to have demonstrated "time reversal" - what bilge! Shall we be shocked and amazed that under exotic conditions, certain particle degradations can be made to run in reverse? Does this demonstrate the existence of a cosmic force or dimension? Such parlor tricks are not going to save anybody's Abraham Lincoln, or get anybody's infant Hitler killed.

It is inevitable that as generations pass, even the ordinary layperson will eventually come to regard our modern era's stubborn belief in the literal existence of time as something quaint, even superstitious. How serious physicists persist in such a silly delusion is beyond me.