# The 2014/15 Collingwood Lecture

#### Professor Martin Hairer (University of Warwick)

#### Fields Medallist 2014

#### "Taming Infinities"

26 February 2015, 4.00pm, CLC013 (Calman Learning Centre)

Professor Martin Hairer is one of the 2014 recipients of the Fields Medal, `for his outstanding contributions to the theory of stochastic partial differential equations, and in particular for the creation of a theory of regularity structures for such equations'. The Fields Medal, officially known as the International Medal for Outstanding Discoveries in Mathematics, is a prize awarded to two, three, or four mathematicians not over 40 years of age at each International Congress of the International Mathematical Union (IMU), a meeting that takes place every four years. The Fields Medal is often viewed as the greatest honour a mathematician can receive. The Fields Medal and the Abel Prize have often been described as the `mathematician's Nobel Prize'.

**Abstract:** Some physical and mathematical theories have the unfortunate feature that if one takes them at face value, many quantities of interest appear to be infinite! Various techniques, usually going under the common name of “renormalisation” have been developed over the years to address this, allowing mathematicians and physicists to tame these infinities. We will tip our toes into some of the mathematical aspects of these techniques and we will see how they have recently been used to make precise analytical statements about the solutions of some equations whose meaning was not even clear until now.