The Miller–Urey experiment (or Urey–Miller experiment) was an experiment that simulated hypothetical conditions thought at the time to be present on the early Earth, and tested for the occurrence of chemical evolution. Specifically, the experiment tested Alexander Oparin's and J. B. S. Haldane's hypothesis that conditions on the primitive Earth favored chemical reactions that synthesized organic compounds from inorganic precursors. Considered to be the classic experiment on the origin of life, it was conducted in 1952 and published in 1953 by Stanley Miller and Harold Urey at the University of Chicago.