Harold Urey

“In general, exchange reactions for the lighter isotopes have equilibrium constants sufficiently different from unity, so that the ratios of concentrations of the isotopes in two compounds which are in equilibrium differ by a few per cents in nearly all cases.”

“Life is not a miracle. It is a natural phenomenon, and can be expected to appear whenever there is a planet whose conditions duplicate those of the”

“I looked for it [heavy hydrogen, deuterium] because I thought it should exist. I didn't know it would have industrial applications or be the basic for the most powerful weapon ever known [the nuclear bomb] ... I thought maybe my discovery might have the practical value of, say, neon in neon s”

“The discovery of deuterium and the marked differences in the physical and chemical properties of hydrogen and deuterium, together with an efficient method for the separation of these isotopes, have opened an interesting field of research in several of the major branches of science.”

“The space program is not only scientific in purpose but also is an expression of man's insistent determination to do the nearly impossible - to explore the unknown, even at great risk.”

“[Pure research] is worth every penny it costs.”

“Nature can always be more complicated than we imagine.”

“[My study of the universe] leaves little doubt that life has occurred on other planets. I doubt if the human race is the most intelligent form of life.”