Pattern formation in non-equilibrium fluid, solid and multiphase systems

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Why does syrup coil when it hits a pancake? What determines the rippled shape of icicles? Why does lava sometimes crack into perfectly hexagonal columns? All these questions are the subject matter of Pattern Formation, the branch of Physics that deals with the emergence of ordered stuctures under driven, open, far-from-equilibrium conditions. Physics usually treats systems in a state of equilibrium, where they show no change in time. A perfect crystal is an example of order that appears in equilibrium. Ordered structures can also appear when a system is driven into motion by outside forces. In fact, most of the order we see in the universe is of this kind. This category of order encompasses everything from ripples on wind-blown sand to the structure of galaxies to Life Itself. Patterns have underlying symmetries and mathematical similarities that can be investigated by a combination of laboratory experiments, theory and computer simulation. Patterns exhibit universal behaviour across many length and time scales. The research program of the Experimental Nonlinear Physics Group at the University of Toronto involves work on icicle and stalactite shapes, patterns in the flow of viscous fluids, like honey, fracture patterns in cracking lava, the flow of liquid crystals and many other experiments. Our aim is to understand the Physics behind these diverse phenomena under the rubric of Pattern Formation, as well as to bring new physical understanding to patterns encountered in fields like geomorphology that are normally thought to be far removed from Physics.