Signed title page to Einstein's work on relativity theory, 1917.
© Science Museum / Science & Society Picture Library
Presentation copy of 'Uber die spezielle und die allgemeine RelativitAtstheorie' (On the Special and General Theory of Relativity), by Albert Einstein (1879-1955), published in Braunschweig in 1917. The page is dedicated by Einstein, with an inscription by the recipient Hans Muhsam, which, translated, reads: 'This copy is the first one which left the printer. It was sent to me by Prof Einstein the moment he had received it, and shortly before I went to France with the army. Hans Muhsam, Berlin, at present at the French Front, April 1917.' Einstein's special and general theories of relativity posited the concept that time does not exist at the same rate for everyone and everything. Special Relativity produced the equation which expreses the equivalence between matter and energy: E=mc squared.