In this video I talk about the assumption that physics explains everything physical—basically the idea that biology is applied chemistry, and chemistry is applied physics. I do not argue that physics is incomplete, I just point out that we have no reason to believe that physics (that is, that branch of science which studies matter at the lowest level) in fact does explain everything, because we can only study physics at extremely high energy levels and almost all of the interesting stuff happens at (comparatively) very low energy levels. If you were to study human beings by throwing them against a wall at 600 miles per hour, you would miss out on all sorts of interesting things that they do.