Michael Elmhirst Cates, FRS, FRSE (born 5 May 1961) is a British physicist. He is Professor of Natural Philosophy and Royal Society Research Professor [1] at the University of Edinburgh.His scientific work is varied, but focuses on the theory of soft matter, such as polymers, colloids, gels, liquid crystals, and granular material. A frequent goal is to create a mathematical model that predicts the stress in a flowing material as a functional of the flow history of that material. Such a mathematical model is called a constitutive equation. Recently he has worked on theories of active matter, particularly dense suspensions of self-propelled particles which can include motile bacteria.Cates is the Principal Investigator of an EPSRC Programme Grant, awarded in 2011,entitled Design Principles for New Soft Materials.