Blurs

Place a coin, plate, or specially designed disk on a hard surface and give it a spin. At first, nothing seems particularly mysterious. The disk rolls and wobbles around its edge. It gradually loses energy, the movement becomes smaller, and you expect it simply to stop. But something strange happens in the final seconds. The wobbling becomes dramatically faster. The sound rises in pitch. Then, almost suddenly, the disk falls flat. This deceptively simple experiment is known as Euler’s Disk, and it has fascinated physicists for decades. The strange final moments Imagine spinning a coin on a table. Initially, the coin may be tilted at a noticeable angle. Its centre of mass moves around while the coin rolls and slides against the surface. As the angle becomes smaller, however, the disk appears to become increasingly unstable. The wobbling gets faster and faster. The sound changes from a relatively low rumble into a rapid, high-pitched chirp. To the human ear, the final moments can sound al...