Der Peter Haasen-Preis wird für eine herausragende, an der Georg-August Universität im weiteren Bereich der Materialwissenschaften abgeschlossene Dissertation vergeben; die auszuzeichnende Dissertation wird von einem international zusammengesetzten Preis-Komitee unter mehreren, von Dozenten der Universität eingereichten Vorschlägen ausgewählt und vom Gremium zur Vergabe des Peter-Haasen-Preises bestätigt.
The Kibble-Zurek mechanism describes the evolution of topological defects like monopoles, grain boundaries, and vortices when a system is cooled by a finite rate through a continuous phase transition. Tom Kibble originally developed the idea for the symmetry breaking of the primordial Higgs field shortly after Big-Bang to describe the formation topological defects in regions which are not connected by causality. Wojciech Zurek applied it to quantum fluids (e.g. suprafluid Helium) to describe the formation of vortices. In this colloquium I present the formation of defects within a two-dimensional colloidal ensemble, monitored by standard video microscopy. The scaling law for defect formation follows exactly the prediction of the Kibble-Zurek mechanism when adopted for the Kosterlitz-Thouless universality.
Emmy Noether's theorem is familiar across a range of physics from classical mechanics to field theory. I describe how the theorem applies in an interesting and nontrivial way to statistical mechanics [1,2]. Rather than the well-known correspondence of an underlying symmetry of a physical system with a conservation law, in thermal systems that are disordered on microscopic scales, it allows to formulate force and torque identities (sum rules) both in- and out-of-equilibrium. The mathematical basis is the invariance of a functional, such as the free energy density functional and the power functional [3]. I will show what these insights have to do with one of Münchhausen's fairy tales, and why the sum rules are useful for carrying out soft matter research.
[1] Noether's Theorem in Statistical Mechanics, S. Hermann and M. Schmidt, Commun. Phys. 4, 176 (2021).
[2] Why Noether's Theorem applies to Statistical Mechanics, S. Hermann and M. Schmidt, J. Phys.: Condens. Matter 34, 213001 (2022).
[3] Power functional theory for many-body dynamics, M. Schmidt, Rev. Mod. Phys. 94, 015007 (2022).
