Feynman, who died in 1988 after four decades on the Caltech faculty, is the only American to appear on the top 10 list, and the only one who did his most important work in the second half of this century. The others are (1) Albert Einstein, (2) Isaac Newton, (3) James Clerk Maxwell, (4) Niels Bohr, (5) Werner Heisenberg, (6) Galileo Galilei, (8) Paul Dirac, (9) Erwin Schrödinger, and (10) Ernest Rutherford.