You’ve heard of string theory. What about knot theory?

A Q&A with a veteran knot theorist discusses the strange origins of the discipline, as well as its modern-day applications. This field of mathematics, rich in aesthetic beauty and intellectual challenges, has come a long way. It involves the study of mathematical knots, which differ from real-world knots in that they have no ends. You can think of each one as a string that crosses over itself a given number of times, and then reconnects with itself to form a closed loop.

Read more: You’ve heard of string theory. What about knot theory?