Leo Philip Kadanoff (born January 14, 1937) is an American physicist. He is a professor of physics (emeritus as of 2004) at the University of Chicago and a former President of the American Physical Society (APS).He has contributed to the fields of statistical physics, chaos theory, and theoretical condensed matter physics.He received Isaac Newton Medal in 2011 for inventing conceptual tools that reveal the deep implications of scale invariance on the behavior of phase transitions and dynamical systems.