## Articles

**Colin Adams**asks when is a molecule knot a molecule? and what happens if you try to build a knot out of sticks?

**Ian Garbett**discusses radioactive decay.

Cookies are set out on a rectangular grid. The bottom left cookie is poisoned.

Two players take it in turn to "chomp" - that is, to eat one of the remaining cookies, plus all the cookies above and to the right of that cookie.

**Matthew Keeling**describes some of the mathematical developments that have improved our understanding and predictive ability.

**Ian Garbett**discusses light attenuation - the way in which light decreases in intensity as it passes through a medium.

**Mark Wainwright**meets the pair and finds out how they did it.