İf you have a billard ball near the hole, and you hit another ball towards to cause the first ball to fall in the hole, according to classical mechanics you can say, the ball has fallen in the hole, because i hit this ball with my ball. First my ball hit the other and then the other ball fallen in the hole. Arrow of time is towards.
But if you do this experiment with electrons, and try to cause one electron to fall in the hole by hitting with another electron, the electron also falls in the hole. But in quantum world, something strange happens. The electron falls in the hole before the other ball hits it. The timeline can run backwards and the cause becames result.
