Albert Einstein was the most famous scientist of the 20th century, whose theories of relativity revolutionized physics and whose name became synonymous with genius. Born in Germany to a secular Jewish family, Einstein developed special relativity in 1905 and general relativity in 1915, fundamentally changing our understanding of space, time, and gravity.
Einstein was also a public intellectual who spoke on political issues. A pacifist who fled Nazi Germany in 1933, he reluctantly signed the letter to FDR recommending atomic research, fearing the Germans might develop the bomb first. After Hiroshima, he became an advocate for international control of nuclear weapons and world government.
Einstein supported socialist economics, Zionism (while criticizing Israeli treatment of Arabs), and civil rights (befriending Paul Robeson). His FBI file ran thousands of pages. He spent his final decades at Princeton, seeking a unified field theory he never found. Einstein died in 1955, having transformed physics and become an icon of intellectual conscience.