## knot

**Mario Livio**looks at an example of strings and knots, taking us from the mysteries of physical matter to the most esoteric outpost of pure mathematics, and back again.

**Professor Gerardus 't Hooft**has always been fascinated by the mathematical mysteries of nature. He tells

*Plus*about his early life, and what our Universe might really be like.

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