A Massachusetts Institute of Technology professor of mathematics and a World War II meteorologist, Lorenz set to work on using computers to help predict the weather.
It was 1961, and getting the models to work was harder than he thought: tiny changes in parameters led to huge differences in results. He called it “deterministic chaos”, which evolved into a new field that is now better known as Chaos Theory, exemplified by a concept Lorenz used to illustrate the concept: the “butterfly effect” (taken from the title of his 1972 presentation, “Predictability: Does the Flap of a Butterfly’s Wings in Brazil Set Off a Tornado in Texas?” The bottom line: perfect weather prediction was impossible even if a perfect computer model could be developed, since it was impossible to get perfect measurements of everything that was happening in nature: a tiny change (say, “wind” from a butterfly’s wings) could grow into a huge disturbance elsewhere (say, a hurricane).
Lorenz’s ideas “profoundly influenced a wide range of basic sciences and brought about one of the most dramatic changes in mankind’s view of nature since Sir Isaac Newton,” said the prize committee when he was awarded the 1991 Kyoto Prize for basic sciences. He died April 15 from cancer. He was 90.956164383562.