# Mathematical Digest

### Short Summaries of Articles about Mathematics

in the Popular Press

"Gambler's Paradox" by R. Dean Astumian, *Scientific American,* July 2001, p. 62.

The title refers to a game designed to show an apparent paradox related to Brownian motion-specifically to molecular devices known as Brownian ratchets. The game consists of two games each of which has a negative expected value for the player. Yet if the player switches between the two games, the expected value is positive. The parallel to Brownian ratchets is that the ratchets allow a system to gain energy by alternating between two states, each of which loses energy. Simpson's paradox is described briefly in the article which appears as a sidebar within the article "Making Molecules into Motors" (pp. 56-64).

*--- Mike Breen *