Albert Einstein, German theoretical physicist, 5 January 1935.
© Associated Press / Science & Society Picture Library
Albert Einstein (1879-1955) lecturing to the American Association for the Advancement of Science at Pittsburgh. Einstein was discussing his latest theory - that it was possible that the universe might be finite. Einstein made fundamental contributions to physics which include his special (1905) and general (1915) theories of relativity, which posited the concept that 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. In 1921, he received the Nobel Prize for Physics. His Jewishness meant that he had to leave Germany during the Nazi period, and went to live in the United States of America, taking citizenship.