We hear two stories of everyday life which are more easily understood if one knows some of the laws of physics, specifically the Mediocrity Principle and the Casimir Effect.

The men and women on staff at This American Life decide to get their testosterone levels tested, to see who has the most and least, and to see if personality traits actually do match up with hormone levels. It turns out to be an exercise that in retrospect, we might not recommend to other close-knit groups of friends or co-workers.

We hear a tape that a man named David Cossin made for a woman in Italy named Allesandra whom he'd met during a week he spent there, and with whom he'd fallen in love. He sent her a dozen tapes, including one where he tries to convince her to move to New York and be with him.