The HGSFP Winter School 2025 took place at the Universitätszentrum Obergurgl in Austria from November 23rd to November 27th, bringing together a diverse group of doctoral researchers from the HGSFP and lecturers. Against the backdrop of the Ötztal Alps, the school provided a platform for academic exchange, covering physics across all scales—from the microscopic interactions of ultracold gases to the grand structure of galactic star clusters.
The core of the scientific program was defined by six in-depth lecture series, each addressing fundamental challenges in modern physics. Natalia Lahén (MPA Garching) delivered a comprehensive course on computational astrophysics and star clusters, detailing how observations of stellar ages and chemical compositions serve as fossil records of galactic evolution, and explaining the hydrodynamical and N-body techniques used to model them. Mark McCaughrean (MPIA) provided an expansive overview of space science, tracing the fifty-year history of the European Space Agency's science program and offering deep insights into the James Webb Space Telescope, from its architectural origins to its current operations. Transitioning to theoretical frameworks, Jan Pawlowski (Heidelberg University) presented on Effective Field Theories, equipping students with the tools to describe strongly correlated phenomena such as spontaneous symmetry breaking and superconductivity across systems ranging from ultracold atoms to QCD. In the realm of soft matter, Falko Ziebert (Heidelberg University) explored biological motion, illustrating how active matter—such as swimming bacteria or crawling cells—can be understood through the lens of hydrodynamics and nonequilibrium physics. Arthur Christianen (ETH Zürich) lectured on the transition from few- to many-body physics in ultracold gases, utilizing a bottom-up perspective to show how collective behavior emerges from fundamental two- and three-body scattering properties. Klaus Pfeilsticker (Heidelberg University) addressed the critical physics of the Earth's climate system, providing a quantitative analysis of the energy budget, anthropogenic radiative forcing, and the complexities of equilibrium climate sensitivity and feedback mechanisms.
Complementing the invited talks, the curriculum was enriched by „Special Lectures“ presented by student volunteers. These sessions focused on essential technical and professional skills, covering topics such as scientific software engineering, the working conditions of doctoral researchers, visualization in Python, FreeCAD, differentiable simulators, and quantum many-body script languages.
The academic exchange extended into two dedicated poster sessions. Every student presented their individual research, resulting in a vibrant cross-disciplinary dialogue. In recognition of scientific excellence and presentation skills, the three best contributions were awarded the traditional poster prize, which is awarded every year in the summer or winter school.
The school's schedule was deliberately structured to balance intensive learning with social connection. We were lucky that the snow arrived just in the right moment for our winter school. Therefore, the extended afternoon breaks allowed participants to explore the high-alpine environment of Obergurgl, with many engaging in skiing, winter hiking, or snow boot tours. In the evenings, the traditional hierarchies of academia were set aside; lecturers and students spent hours together discussing scientific and non-scientific topics, playing board games, relaxing in the sauna or having a movie night about the ESA Rosetta mission.
We gratefully acknowledge the Heidelberg Graduate School for Physics for the generous support that made this winter school possible.
Anna Lena Schaible and Carlos Pastor Marcos (for the Orga Team)
Pictures from top to bottom:
1 — PhD students and lecturers of the HGSFP Winter School 2025
2 — Alpine inspiration: The venue provided lecture halls with views of the Otztal Alps and opened directly onto the snow
3 — PhD students listening to one of the special lectures
4 — Poster session, where students presented their research to their fellows
5 — Poster session
6 — This years poster prize winners with the traditional HGSFP poster trophy: Veronika Lipatova, Christina Schmidt und Uri Sharell
7 — Skiing in the afternoon break
8 — Hiking in the winter landscape in the free time
