Professor Julia Yeomans OBE FRS from the Department of Physics at the University of Oxford has been awarded the 2025 Institute of Physics Paul Dirac Medal and Prize. The IOP gold Dirac Medal recognises Professor Yeomans’ contributions to understanding the collective behaviour of active particles and her work highlighting the relevance of active physics to living matter.
Active systems are collections of particles that consume energy individually, keeping them out of thermodynamic equilibrium. When such particles are densely packed, they can display striking collective behaviour such as the coordinated rotation of cell clusters or the swirling patterns seen in starling murmurations. An early paper by Professor Yeomans identified turbulent-like behaviour in active fluids, comparing experiments with continuum and agent-based modelling. She has worked extensively on confined active fluids, identifying novel flow states, now confirmed in experiments, and demonstrating that activity can lead to phase ordering and surface anchoring.
The relevance of active matter theories to biology was beautifully illustrated when, with Amin Doostmohammadi, she teamed up with experimental colleagues to provide the first demonstration of motile topological defects in layers of epithelial cells, arguing that these are preferred sites for cell death. This paper has initiated a surge of research on activity and topological defects in living systems to which Professor Yeomans has contributed through studies of the collective motion of cells, tissue reorganisation in early embryogenesis, and the pattern of lesions in breast cancer.
‘It is an honour to receive the Dirac award, which celebrates the power of using mathematics to describe reality,’ comments Professor Yeomans. ‘This recognition is also a tribute to my collaborators and students whom I thank for many enjoyable conversations and for their generosity in sharing their insights.’
‘Julia’s work has shed new light on a wide range of complex phenomena found in soft matter and biological physics inspiring new lines of enquiry for theorists and experimentalists alike,’ comments Professor Andrew Boothroyd, Head of Department. ‘She is a much-respected leader in her field and this recognition is richly deserved.’
The IOP gold Paul Dirac Medal and Prize recognises outstanding and sustained contributions to computational, mathematical or theoretical physics. Professor Yeomans joins fellow laureates from the University of Oxford’s Department of Physics: Professor Gavin Salam (2023); Professor Steven Balbus (2021); Professor John Chalker (2018);
Professor Tim Palmer (2014); Professor Graham Ross (2012); Professor James Binney (2010); and Professor David Sherrington (2007).