This is Perlin Noise.

This is Perlin Noise.

In case you don't know this story, Ken Perlin was dissatisfied with the unnatural look of computer-generated imagery in the early 1980s after working on the digital effects for Tron. So he developed a procedural texture primitive to create more realistic graphics. Despite its pseudo-random appearance, the function's visual details are uniform in size. It's a good tool for generating natural-looking terrain in video games and other computer-generated environments.

And beautiful energy flows.