Like what I make? Want fewer sponsorship ad reads? Consider contributing to my Patreon at https://patreon.com/OurOwnDevices The Crookes Radiometer or "Light Mill", invented in 1873 by British physicist Sir William Crookes, is a simple heat engine that converts light into rotational motion. Though simple in construction and commonly sold as a desk toy or educational aid, the physics of the Radiometer are surprisingly complex, and even 150 years after its invention, physicists are still not entirely certain how it works. SOURCES: https://math.ucr.edu/home/baez/physics/General/LightMill/light-mill.html https://zenodo.org/record/1432450 https://golem.ph.utexas.edu/category/2008/07/light_mills.html https://phys.org/news/2010-07-nano-sized-mill-micro-sized-disk-video.html https://cs.stanford.edu/people/zjl/pdf/mill0.pdf