ERIK MCLEAN / UNSPLASH

Physikalisches Kolloquium

Freitag, 8. Mai 2026 17:00 Uhr  Polymers - Soft Matter as Model Systems for Physics

Prof. Dr. Kurt Kremer, Max-Planck-Institut für Polymerforschung, Mainz Polymers / Soft Matter as Model Systems for Physics Kurt Kremer; Max Planck Institute for Polymer Research, Mainz, Germany Polymers, long chain molecules, comprise important materials of our daily life, being it simple commodities with all their advantages and disadvantages or high-tech materials in electronics or medicine, to give just two examples. Furthermore, biopolymers such as cellulose or proteins are central functional constituents of living organisms. Not surprisingly, they have been subject of applied physics research since their discovery/invention. This application focused view, however, changed with de Gennes’ discovery of the n→0 theorem, showing that the inverse chain length 1/N, N being the number of chain repeat units, can be mapped onto the distance |T-Tc|/Tc from the critical point in a n-vector spin model. At about the same time computer simulations became powerful tools to study critical phenomena in spin systems, complemented by experiment, most notably neutron scattering for the case of polymers. At that point polymers became important and versatile systems to study general questions of critical phenomena. Polymers/Soft Matter display slow dynamics and are susceptible to small molecular stimuli. Thus, local chemistry specific aspects like minute changes in local interactions easily turn into macroscopic property changes. At that point generic physical concepts meet the consequences of chemically detailed interactions. This interplay makes soft matter so versatile and so interesting. The talk will review a few characteristic examples, where such effects lead to physically interesting phenomena, which apply to modern statistical physics (active systems, glass transition) as well as soft matter materials science (nanoporous materials). Finally, challenges and perspectives for physics of soft matter but also for new physics studied by soft matter will be shortly discussed.

Teilchenkolloquium

Litht Ion Collisions at LHC

Dr. Aleksas Mazeliauskas, Institut für Theoretische Physik Universität Heidelberg Light-Ion Collisions at the LHC Aleksas Mazeliauskas Kirchhoff Institut, Universität Heidelberg The Large Hadron Collider is not only a machine for discovering new particles — it is also a laboratory for creating and studying a new phase of QCD matter. When lead nuclei collide at ultrarelativistic energies, the resulting energy densities far exceed the QCD confinement scale, melting hadrons into a Quark-Gluon Plasma (QGP): a strongly coupled, nearly perfect fluid well-described by relativistic Navier-Stokes equations. Yet a fundamental question remains: how do a handful of elementary particles thermalize and form a collective medium in such a vanishingly short window of time? Light-ion collisions probe the critical regime where nuclear structure, perturbative QCD, and quark–gluon plasma physics intersect. The first oxygen–oxygen and neon– neon runs at the LHC in July 2025 have opened a new chapter in the LHC ion program, bridging the gap between proton–proton and heavy-ion collisions in a controlled and theoretically tractable way. For a decade, experiments had found QGP-like collective flow even in proton–proton collisions, while jet quenching — the canonical signature of QGP — remained elusive in small systems. The 2025 runs have changed the picture: first results show evidence of jet quenching in systems with as few as ten participating nucleons, and collective flow measurements in oxygen–oxygen and neon–neon collisions are in good agreement with hydrodynamic predictions using ab initio nuclear structure calculations. I will discuss what these results reveal about thermalization, collectivity, and the boundaries of the QGP phase — and what might come next in the ion program at the LHC.

Astronomisches Kolloquium

Dienstag, 28. April 2026 16:30 Uhr  Strongly Interacting Multiple Planet Systems as a Rosetta Stone for Planet Formation

Trifon Trifonov , Heidelberg University (ZAH/LSW) Well-characterised multiple-exoplanet systems are particularly valuable because their physical and dynamical architectures preserve a fossil record of their formation and subsequent dynamical evolution. In strongly interacting systems composed of massive Jovian planets detected through radial velocities (RVs) and transit timing variations (TTVs), the mutual gravitational interactions are strong enough to constrain the system architecture with high precision through N-body dynamical modelling. Such models recover the time-dependent osculating orbital elements that more accurately describe the true configuration and dynamical state of the system. Reproducing the observed dynamical architecture of these systems enables reverse engineering of the initial conditions under which they formed. In particular, planetary systems trapped in mean-motion resonances (MMRs) retain a “memory” of the migration process, including the possible migration rate during the proto-planetary disk phase, the excitation of eccentricity, and disk-planet interactions at the moment of capture. In this talk, I will present the cascade from observations to detailed dynamical modelling of the data, and the following migration simulations. I will highlight several exceptionally well-characterised giant planet systems that provide important insights into the mechanisms shaping planetary systems during their formation and early evolution.

Zentrum für Quantendynamik Kolloquium

Dienstag, 28. April 2026 09:30 Uhr  Development of a transportable Ytterbium optical lattice clock

Fatima Rahmouni, Université Sorbonne Paris Nord