"Nature's Detangler," by Fenella Saunders. Discover, July 2001.
As the tying and untying of biological molecules cannot be observed directly, researchers Eli Ben-Naim, Robert Ecke and Zahir Daya have experimented with simple spools of chain from a hardware store to create knots and study their unraveling. Saunders reports that they cut the chains into segments of 30 to 300 beads long, tied them into knots, and set them on a plate that vibrated 13 times a second. "The chains wiggled around, settling into many semistable configurations until one end of the chain slipped through and untied the knot," she writes. The more beads, the longer it took to untangle, but all the knots eventually came undone in patterns that depended upon the type of knot. Ben-Naim says that this work may shed light on protein folds.
--- Annette Emerson