I would suggest <A HREF="https://en.wikipedia.org/wiki/Chaos_theory">chaos theory</A> as originating from examples of chaotic systems in physics. As described <A HREF="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3202497/">here</A>, there are plenty of mathematicians among the pioneers (Poincaré, Kolmogorov,Lorenz,Feigenbaum...), but the motivation came from physics (planetary motion, turbulence,weather,population dynamics...).