Simon Donaldson

"... the dialogue between mathematical physics, geometry, and algebraic topology. The interaction between these subjects has been such a dominant feature of research developments in the past few years that it seems scarcely necessary to recite a list of examples: in fact, on the mathematical side it is quite hard to think of active areas in geometry and topology which have not been noticeably influenced by insights from physics—where by "physics" we mean particularly quantum field theory—and on the other hand the geometrisation of fundamental physical concepts is a profound and pervasive development."

"Geometers have studied the topology of closed surfaces and their higher- dimensional analogues (manifolds) for a long time. But a remarkable breakthrough came in the early 1980s when Simon Donaldson found some totally new and unexpected invariants of four-dimensional manifolds. These were based on the Yang–Mills equations of physics but it was not until later that Edward Witten again showed how to interpret Donaldson's invariants in terms of quantum field theory. Later still, using duality ideas from string theory, Witten and Seiberg made a significant improvement of Donaldson theory which led to solutions of old problems."