Albert Einstein at Princeton, USA, 4 February 1944.

UNITED STATES – FEBRUARY 01: Albert Einstein at Princeton, USA, 4 February 1944. The physicist, philosopher and humanitarian Albert Einstein (1879-1955) solving a puzzle whilst smoking a pipe. ‘Nursery puzzles are sent to Einstein from friends all over the world. He loves to solve them’. Einstein was born in Germany and emigrated to the USA in 1933. He was awarded the Nobel prize for physics in 1921. Einstein made fundamental contributions to physics which include his special and general theories of relativity, which posited that the concept of time does not exist at the same rate for everyone and everything. Special Relativity produced the equation which expresses the equivalence between matter and energy: E=mc squared. (Photo by Daily Herald Archive/SSPL/Getty Images)