In 1971, physicist Burton Richter of Stanford Linear Accelerator Center was building a new type of particle collider called a storage ring. The lab’s two-mile-long linear accelerator—housed in what was then the longest building in the world—would shoot electrons and their antimatter twins, called positrons, into the 80-meter-diameter Stanford Positron Electron Accelerating Ring, and SPEAR would set the beams of particles on a collision course. Richter and his colleagues stood by to examine the debris to see what discoveries came out.