Physics and Astronomy Colloquium

The mathematics and physics of knots has a long and fascinating
history, starting from a model of an atom suggested by W.Thompson
(Lord Kelvin). Knots in DNA are abundant and important. Recently, we surveyed the protein data bank and found that evolution for some as yet unknown reason preferred unknotted proteins, although a few beautiful counterexamples were found, including Gordian knot in human ubiquitin hydrolase. In theoretical aspect, the field was long dominated by either highly abstract mathematics or computer simulations. Recently, some progress was made in the direction of physical understanding of knots. In the talk, all these various aspects will be reviewed in some mixture.