Albert Einstein (1879-1955) Germany, Switzerland, U.S.A.

Albert Einstein was probably the greatest physicist in all of history (some would say Isaac Newton shares that honor). The atomic theory achieved general acceptance only after Einstein's 1905 paper which showed that atoms' discreteness explained Brownian motion. Another famous 1905 paper introduced the famous equation E = mc²; yet Einstein published other papers that same year, two of which were more important and influential than either of the two just mentioned! No wonder that physicists speak of the Miracle Year without bothering to qualify it as Einstein's Miracle Year! (Altogether Einstein published at least 300 books or papers on physics.)

Although most famous for his Special and General Theories of Relativity, Einstein's discovery of the photon made him the key pioneer in quantum theory (and led to his only Nobel Prize). Many years later, he was first to call attention to the "spooky" nature of quantum entanglement.

Einstein certainly has the breadth, depth, and historical importance to qualify for this list; but his genius and significance were not in the field of pure mathematics. (He acknowledged his limitation, writing "I admire the elegance of your [Levi-Civita's] method of computation; it must be nice to ride through these fields upon the horse of true mathematics while the like of us have to make our way laboriously on foot.") Einstein was a mathematician, however; he pioneered the application of tensor calculus to physics and invented the "Einstein summation notation." I've chosen to include him on this list because his extreme greatness overrides his focus away from math. Einstein ranks #10 on Michael Hart's famous list of the Most Influential Persons in History. His General Theory of Relativity has been called the most creative and original scientific theory ever. Einstein once wrote "... the creative principle resides in mathematics [; thus] I hold it true that pure thought can grasp reality, as the ancients dreamed."