The Heart
Nine points. Each one joined to the point with twice its number. Rodin’s loop, with the digits stripped away.
Ninety points. Every point still joined to its double.
Four hundred points. A heart appears, drawn with nothing but straight lines. It has a name: the cardioid.
Change the rule and new shapes bloom. Times three draws a kidney with two lobes. Times four, three lobes. Every step up the times table grows another one.
Back to doubling. Now look at what has been hiding under the heart.
This is the Mandelbrot set. It comes from one rule: take a number, square it, add a constant, repeat. It has been called the most complex object in mathematics.
Its body is the heart you just drew with straight lines. Exactly the same curve, at three quarters of the size.
The bulbs growing off the heart are ordered by the same arithmetic. The big one on top is the period-3 bulb, and its gateway is marked by two angles: 1/7 and 2/7 of a full turn.
One seventh, again.
Every point of this set is a doorway to a world of its own, called a Julia set. Move across the picture, or tap it, to look through.