Fluid Gears Rotate Without Teeth

NYU scientists just unveiled gears with no teeth, using swirling fluid to make rotors spin—think “bubble bath meets clockwork.” Published in Physical Review Letters, the team says they can dial rotation speed and even flip direction with fluid flows instead of clunky metal teeth. Cue the internet chorus: one camp is hyped by the idea of softer, jam-proof motion, while the other is shouting “reinventing slushomatics!” and “virtually zero torque!”

Commenters are spicy. vlachen bristles at the vibe of “old gears bad,” but still sees wild possibilities, noting the video’s counter-swirl hints at inefficiency. dvh drops the mic with “Zero torque, right?” and debatem1 calls it “old school fluid couplings” with a new coat of glycerol. Meanwhile, zahlman wants to know if we can actually design this stuff on purpose or if it’s still lab trial-and-error, and Y_Y jokes it’s the kind of thing a famous fluid scientist would have as a bath toy.

The paper’s authors (Jun Zhang, Leif Ristroph, and Jesse Etan Smith) show close rotors acting like gears and far ones like belt pulleys, with tiny bubbles revealing the flow magic. Fans imagine use in delicate robots or micro-machines where metal teeth break; skeptics meme it as “dentist-approved gears” and “slushomatic 2.0.” Whether it’s a revolution or just a really fancy whirlpool, the comments are doing the heavy lifting—because someone has to provide the torque. Read the full release via NYU.