The FBI spied on him for decades.

Shortly before Hitler rose to power in 1933, Einstein left Berlin for the United States and took a position at the Institute for Advanced Study in Princeton, New Jersey. His support for pacifist, civil rights and left-wing causes had already drawn suspicion from J. Edgar Hoover’s FBI, and after his arrival on American shores, the Bureau launched what would eventually become a 22-year surveillance campaign. Agents listened to the physicist’s phone calls, opened his mail and rooted through his trash in the hope of unmasking him as a subversive or a Soviet spy. They even investigated tips that he was building a death ray. The project came up empty handed, but by the time Einstein died in 1955, his FBI file totaled a whopping 1,800 pages.