Most people take time for granted. And I don't just mean that it's hard to find enough time to do interesting things. I mean that the very notion that time flows in one direction is just a given in most peoples lives, and rarely noticed.
But to a physicist, contemplating time reveals an odd realization; none of the physical laws that we have discovered seem to restrict how or why time should flow forward vs. backwards. In other words, our physical laws are symmetric, and make no distinction between whether time is going forwards or backwards.
But watch this video. It is really easy to tell when time (and the video) is running forward vs. backwards. Why is that?
Follow this link for Sean's nice post on the Arrow of Time for some extra insights.
