Ferrofluids are cool. Glowsticks are cool. And what happens when you combine them is pretty neat, too.
Ferrofluids are liquids that hold tiny nano-sized particles of magnetic material within themselves in suspension. When they experience a magnetic field, they assume all kinds of interesting patterns, from complex swirling loops to spiky hedgehog-like domes.
Here, Physics Girl adds a little of the luminescent fluid from glowsticks to the mix, to show the shapes and patterns more clearly. She does a nice job of explaining the properties of ferrofluids, too — so it's worth watching the video for more than just the pretty footage.