The latest Citizen Scientist has a great article about knots Dorian M. Raymer! –
What governs the annoying formation of random knots in strings, cords, and garden hoses? Mathematicians have studied knots for more than a century, but only in the abstract. As physicists, we have also found this to be an interesting physics problem. What is a knot? How many different knots exist? How do knots form? The word knot has several meanings. Colloquially, a knot refers to a string that is tangled or interlaced with itself or another strand of rope.
HOW TO – Generate and identify random knots in a piece of string – Link.