Newton's disc is a fun illusion that relies on the persistence of vision. In real life, if you spin a coloured disc quickly like this, the colours will eventually blur to a white or grey. However, on a screen you run up against the limitations of the refresh rate. This is a silly little demo to illustrate that.
⚠ Note: best case this will give you a weird headache. Worst case, it's going to flash like a strobe light when you ramp up the speed - so be careful! 😵💫 Also, if you have reduced motion on I've just turned off animations completely to be safe!