Fifty years ago, “fractal” was born. In a 1975 book, the Polish-French-American mathematician Benoit B. Mandelbrot coined the term to describe a family of rough, fragmented shapes that fall outside ...

In the mid-1980s, like Walkman cassette players and tie-dyed shirts, the buglike silhouette of the Mandelbrot set was everywhere. Students plastered it to dorm room walls around the world.