American chemist and biologist noted for his pioneering work on the origin of life on Earth and on exobiology, the study of life beyond Earth.

Miller studied at the University of California, graduating in 1951, and was awarded a PhD in chemistry at the University of Chicago three years later. He then returned to California to work in the chemistry department of the state university at San Diego.

While Miller was studying for his PhD, his supervisor, Harold Urey, suggested a now classic experiment based on the premise that the Earth's early atmosphere had been rich in ammonia, methane and hydrogen. Miller and Urey mixed the compounds with water in a flask and ran an electrical charge through them, a substitute for the sun's ultraviolet radiation. The contents of the flask reacted to produce the amino acids that are essential for the formation of living matter.

It seemed as if the big questions about the origin of life might be answered within decades. Some years later, the discovery of amino acids in a meteorite lent further credence to Miller's ideas. However, since that time doubts have been cast upon his findings and beliefs about the composition of Earth's early atmosphere have changed.