By The Associated Press
WASHINGTON — Edward Lorenz, the father of chaos theory, died Wednesday at his home in Cambridge, Mass. He was 90.
He was a professor at the Massachusetts Institute of Technology when he came up with the scientific concept that small effects lead to big changes, a simple example of which is known as the "butterfly effect." He explained how something as minuscule as a butterfly flapping its wings in Brazil changes the constantly moving atmosphere in ways that could later trigger tornadoes in Texas.
Lorenz came up with the concept in the 1960s, said Kevin Trenberth, a student of Lorenz's who is now climate analysis chief at the National Center for Atmospheric Research. Lorenz ran a calculation through a creaky computer twice and came up with vastly different answers. When he tried to figure out what happened, he noticed that a slight decimal point change — less than 0.0001 — wound up leading to significant error. That error became a seminal scientific paper, presented in 1972, about the butterfly effect.
Lorenz was "the quiet geek" who turned the old concept of "wiggle room" into hard numbers and scientific theory, said longtime friend Jerry Mahlman, a retired federal climate scientist. Meteorologists today base their forecasts on his techniques. Lorenz's 1967 book "The Nature and Theory of the General Circulation of the Atmosphere" is considered a classic textbook in meteorology.