An experiment conducted by Stanley Miller (1930–2007) and Harold Urey (1893–1981) in 1953 at the University of Chicago; it showed that amino acids could be synthesized by starting with a mixture of methane, ammonia, and hydrogen to represent what was then considered to be the early atmosphere of the earth, water to represent the early oceans, and electrical sparks to represent lightning. Within a few days amino acids were formed. It is now thought that the early atmosphere was not the mixture of gases that Miller and Urey supposed; however, their experiment has been very significant in debates on the origin of life.