What is this?

This little WebGL script visualizes the Spherical Harmonics. A quick rundown about what that means:

The Spherical Harmonics are results of a rather complex (pun not intended) function, commonly denoted with the capital letter Y. This function depends on two parameters: l and m. Y is defined for all integers l and m such that 0 ≤ m ≤ l. The function takes in two variables: θ and φ. The function essentially takes in a sphere and deforms it in a specific way.

This tool plots this function. Since the results of the function are complex, it isn't really easy to plot the function in all its glory. (The function takes in two variables and spits out another two. We'd need 4D screens to see it in all its glory). So this widget just plots the radius of the complex number. Think of complex numbers as points in 2D space. I plot the distance of that point from the origin.

Since this function can also return negative values, it is common to plot the absolute value, and colour regions according to their sign. Here, green represents non-negative values and red represents negative values.