By the time World War II ended with atomic mushroom clouds erupting over Hiroshima and Nagasaki, Einstein the icon had long since overshadowed Einstein the man. His greatest contributions to theoretical physics had been made in the 1900s and 1910s, his Nobel Prize awarded in 1921. Einstein spent the last thirty years of his life vainly struggling to formulate what he called a "unified field theory," a single mathematical model that could explain all the laws of physics. He never found his answer. (Today, half a century after Einstein's death, scientists continue to search for this Holy Grail of theoretical physics.) Even as Einstein was frustrated in his unified field work, his fame and status as the world's embodiment of pure genius continued to grow. It is this late-period Einstein, the mad professor with the rebellious white hair, that lives on today on our t-shirts and bumper stickers.
In his later years, Einstein continued to speak out on social and political issues, still unafraid to stand against the conventional wisdom of the moment. Einstein, who had long collaborated with fellow scientists in the Eastern bloc, deplored the Cold War and the domestic Red Scare that accompanied it. He spoke out in favor of socialism and one world government, joined radical civil rights organizations, and defended the character of friends who were Communists. All of these activities struck many in McCarthy-era America as deeply suspicious; the FBI opened a file on Einstein, and it soon grew to nearly 1,500 pages.
At the same time, Einstein continued be a staunch supporter of the new nation of Israel but also a vocal critic of what he saw as excessive violence on the part of some Israelis—especially members of Menachem Begin's right-wing Irgun militia—toward Palestinian Arabs. (Even while the 1948 Israeli War of Independence still raged, Einstein co-authored a letter to the New York Times that denounced Begin as a "terrorist" and "Fascist" responsible for massacring Palestinian civilians at the village of Deir Yassin.