BUFFALO, N.Y. — You may not have heard of knot theory. But take it from Bill Menasco, a knot theorist of 35 years: This field of mathematics, rich in aesthetic beauty and intellectual challenges, has ...

Find a string. Really. Do it. Now twist, tie and tangle it as much as you like. Finally, attach the two loose ends of your string together to make a closed loop. (This is a crucial step.) What you ...

The original version of this story appeared in Quanta Magazine. In 1876, Peter Guthrie Tait set out to measure what he called the “beknottedness” of knots. The Scottish mathematician, whose research ...