How to create trippy whirlpools in your martini, according to physics

Shaking a martini glass instead of the drink itself creates mesmerising patterns of small whirlpools.

Zhao Pan at the University of Waterloo, Canada, was travelling abroad when a drink he ordered in a bar led him to an intriguing physics discovery. His martini was full of bubbles, and because he was sitting by a window, he could clearly see them trace a complicated structure of vortices when he shook the glass back and forth.

Later, he repeated the process in the …