Scientists trying to take advantage of the unusual properties of the quantum realm say they have successfully simulated a method of backward time travel that allowed them to change an event after the fact one out of four times. The Cambridge University team is quick to caution that they have not built a time machine, per se, but also note how their process doesn’t violate physics while changing past events after they have happened.
But how do they know they’ve changed the past because that past will be the established past. But then they’d try and change it again thinking they’d failed but then…oh no I’ve gone cross eyed.