I show you a movie starting with a broken bowl on a floor with a puddle of milk and jumble of cereal around it. Spontaneously it all comes back together again, cereal and milk neatly confined by the bowl and suddenly it all pitches upwards towards a kitchen table. But it slows as it reaches up and rounds the table’s edge where it then stops. You instantly know this movie is being played backwards. We don’t have any experience of things like this happening in real life.
The trouble comes in reconciling this everyday view of nature backed up by classical thermodynamics with quantum physics, where most (all?) processes are reversible. This is a big gray area in our understanding which few scientists have dared tread (one of them was Ilya Prigogine).
John Wheeler held out the prospect that the past might indeed not be definitive until a conscious entity observes evidence of it. He came up with a variant on an old parlor game to illustrate the idea.
At least one physicist, Julian Barbour, was impressed enough by the timeless Wheeler-DeWitt equation for quantum gravity that he proposed a static cosmology where time is illusory. This hasn’t met with much favor.