Are all phase transitions of Landau type in disguise?

3 PM, 9 Oct 2026

Sakura Schafer-Nameki explores how generalised symmetries extend Landau’s theory of phase transitions—and reveal where it still falls short.

Ice melts and a magnet loses its magnetism when heated. Lev Landau explained such phase transitions through symmetry: each phase is defined by the symmetries it breaks, revealed by an order parameter such as magnetisation. Transitions that fall outside this picture have long posed a puzzle.

The notion of symmetry has recently been broadened to include so-called non-invertible symmetries. Symmetry topological field theory, which separates symmetry from dynamics, extends Landau’s paradigm to this setting. Many transitions that appear to lie beyond Landau can then be understood as symmetry breaking in disguise, after a change of viewpoint known as gauging.

In this colloquium, Prof. Sakura Schafer-Nameki asks whether Landau was right after all. The answer is almost, but not quite: transitions between twin phases admit no viewpoint in which they break a symmetry, and arise even for finite groups. Generalised symmetries therefore reveal something new even about ordinary ones.

Event information

This event takes place at 3 o’clock on Friday 9 October in the Faraday seminar room of the London Institute for Mathematical Sciences, on the second floor of the Royal Institution. LIMS colloquia are sponsored by Cognia.

Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?
Are all phase transitions of Landau type in disguise?

Speakers

Sakura Schafer-Nameki

Sakura Schafer-Nameki is a professor of mathematical physics at Oxford. She studies generalised and categorical symmetries in quantum field theory, topological phases of matter, quantum information, and the deep connections between geometry, quantum field theory and string theory.