Tie a trefoil knot in a piece of string, seal the ends together, and try to wiggle it free without cutting. In three-dimensional space, the knot holds firm. Add a fourth spatial dimension, however, ...

Copper and lutetium metal ions chaperone this molecular strand into a three-twist knot. Credit: Credit: Stuart Jantzen, Biocinematics It’s annoyingly easy to tangle your headphones into a mess of ...