In physics past, present and future are effectively the same. The linearity and directionality of time is only singularly experienced by humans due to our biological, neurological and philosophical wiring. To be clear, time exists, but its movement is in question.Time is dependent on observation. And time is observed by humans as unidirectional.
In short (and greatly simplified), the directionality of time emerges from the merging of quantum physics and classical mechanics and something called decoherence. Decoherence “can be viewed as the loss of information from a system into the environment” and provides an explanation for the perception of transition from one system state to a mixture of states. This process is theoretically explained most prominently in the Wheeler-DeWitt equation.
However, this understanding of the directionality of time is now being questioned in a new paper. Via Wired:
“The two scientists who penned this recent paper say that, in the Wheeler-DeWitt equation, gravity’s effects kick in too slowly to account for a universal arrow of time. ‘If you look at examples and do the math, the equation doesn’t explain how time’s direction emerges,’ says Robert Lanza, a biologist, polymath, and co-author of the paper. In other words, those nimble quantum particles ought to be able to keep their property of superposition before gravity grabs hold. And if, say, gravity is too weak to hold an interaction between to molecules as they decohere into something larger, then there’s no way it can force them to move in the same direction, time-wise.
“If that math doesn’t check out, that leaves the observer: Us. Time moves as it does because humans are biologically, neurologically, philosophically hardwired to experience it that way. It’s like a macro-scale version of Schrödinger’s cat. A faraway corner of the universe might be moving future to past. But the moment humans point a telescope in that direction, time conforms to the past-future flow. ‘In his papers on relativity, Einstein showed that time was relative to the observer,’ says Lanza. ‘Our paper takes this one step further, arguing that the observer actually creates it’.”
That is to say time does not actually exist outside of the experience of the observer, in this case humans. Time is not only relative, as argued by Einstein, but dependent. And since time is essentially a way for outside parties to stitch together the universe, this would mean the universe exists solely due to our perception of it.
Have a nice day.