Institute for Theoretical Physics

27/10/25

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof. Alexander Rohrbach

Correlated photons in sub-diffraction imaging and correlated motions in biophysical interactions

Virus-like particles (VLPs) diffuse with tremendous speeds around lung cells to find docking sites. Interferences of partially coherent photons in 100 Hz Rotating Coherent Scattering (ROCS) imaging can make 100 nm small VLPs visible, even behind living cells. In this talk I discuss how incoming photons and amplified photons Ei.Es scattered from virus-like particles f(r,t,w) can be concerted in such a way that their spatio-temporal correlations (coherence) provide high-speed, super-resolution images giving insights into virus-infection or material specific molecular polarizabilities.

Furthermore, I elucidate how the coupling between bacteria-like particles and living cells is investigated by controlling distance and contact with laser traps and MHz interferometric particle tracking. I discuss correlated particle motions, resulting from timescale dependent memory effects in viscoelastic media. Using a frequency decomposition of the tracked particle motions, the apparently invisible binding of particles to the cell can be made visible.

Kontakt: Prof. Jens Niemeyer / Dr. Richard Vink

10/11/25

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof. Koji Hashimoto

Neural networks and quantum mechanics

In today’s revolutionary AI development, physics has played a significant role, as it is obvious from the Novel prize in 2024. In this talk, I point out a certain similarity between neural networks and quantum mechanics. Both have almost one century of history, while their intertwining started quite recently.

In the first half of the colloquium, I briefly summarize the reasons why neural networks are strong tools in physics, and introduce the basic AI methods. As a director of MLPhys initiative in Japan, I will report recent results of research unifying AI and theoretical physics in Japan, ranging from lattice QFT and condensed matter physics to automated mathematics.

In the second half of the colloquium, I explain our discovery of the similarity between neural networks and quantum mechanics. I provide a novel map with which a wide class of Euclidean quantum mechanical systems can be cast into the form of a neural network with a statistical summation over network parameters, which brings about a neural network representation of interacting quantum systems / field theories. In this manner, two major fields --- AI and physics --- can be joined together, which hopefully will foster the coming century of sciences.

Kontakt: Prof. Jens Niemeyer / Dr. Richard Vink

17/11/25

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof. Jenny Suckale

When Earth Systems Snap: The Hidden Triggers of Natural Disasters

How fast can ice sheets disintegrate? When do induced earthquakes pose unacceptable risk? Why do volcanoes erupt? And how can we limit the destructive reach of tsunamis? The hidden trigger of what at first glance might seem like disparate systems is a sudden transition from distributed deformation to localized sliding. Independent of whether this transition occurs in ice, rock, magma, or sand it is associated with a sudden shift in the time scale at which the natural system responds at the small scale, causing an abrupt change in the dynamic of the natural system at the large scale. It thus lies at the heart of seemingly distinct natural disasters such as ice-sheet collapse, explosive volcanic eruptions, or injection-induced earthquakes. By developing computational models that are both process-based and testable against observations, I aim to uncover the physics that governs these transitions and translate that knowledge into strategies for reducing risk.

Kontakt: Prof. Jens Niemeyer / Dr. Richard Vink

08/12/25

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof. Zvonimir Dogic

Active assembly of soft materials

Equilibrium self-assembly and conventional materials processing techniques fall far short of mimicking dynamic self-actuating processes that are commonplace throughout biology. To bridge the gap between living and synthetic matter, we study adhesive non-thermal fibers immersed in an active fluid. Autonomous chaotic flows power non-equilibrium fiber dynamics, inducing their collisions, generating connections, and weaving a membrane-shaped elastic network. This active assembly generates a hierarchy of shapes, structures, and dynamical processes spanning nanometers to centimeters. Ultimately, it generates an active membrane that exhibits global limit cycles induced by a non-reciprocal coupling between the elastic membrane deformations and the alignment axis of the polar active fluid. Our work merges self-assembly with active matter, demonstrating self-processing materials wherein hierarchical life-like structures and dynamics emerge from an initially structureless suspension.

Kontakt: Prof. Jens Niemeyer / Dr. Richard Vink

15/12/25

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Peter-Haasen-Preisverleihungsveranstaltung

Peter-Haasen Prize Ceremony

Prize winner 2025: Dr. Jan Philipp Bange, I. Physikalisches Institut, Uni Göttingen.

Ultrafast exciton dynamics in moiré heterostructures

Kontakt: Prof. Astrid Pundt

12/01/26

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof. Pascal Klein

CANCELED: Antrittsvorlesung Prof. Pascal Klein

Unfortunately, the Antrittsvorlesung by Prof. Pascal Klein on Monday, January 12th has to be canceled due to health reasons. We will identify an alternative date for the event and let you know.

Kontakt: Dekanat Physik

19/01/26

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof. Dr. Jochen Liske

The Standard Model of Cosmology: a Status Report

Over the course of the past several decades, Observational Cosmology has made great progress in establishing a Standard Model of Cosmology: LambdaCDM. This model successfully reproduces and explains a vast array of cosmological observations. These successes notwithstanding, LambdaCDM continues to be plagued by several rather obvious and fundamental issues, including: What is Dark Matter? What causes the acceleration of the expansion of the Universe? Why do different types of measurements of the current expansion rate yield different results? In this personally biased talk I will review some aspects of the current status of these issues.

Kontakt: Prof. Jens Niemeyer / Dr. Richard Vink

02/02/26

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof. Petra Schwille

The complex task of simplifying biology

Cells are by definition the smallest units of life, but in contrast to the hydrogen atom, i.e., the smallest unit of chemistry that we can fully describe using the laws of physics, there is no chance for their coherent fundamental understanding. The reason is that more than 3 billions of years of evolution have thoroughly complexified living systems to the point that today, only computers and AI may be able to comprehend them in their entirety. In the quest to define more quantitatively approachable living systems, we are designing minimal cells from the bottom-up. We have particularly focused on the phenomenon of cell division, aiming at membrane compartments that are able to orchestrate their own division through energy dissipation. I will present our latest results and explain why obtaining simplicity can be challenging if the role models - living cells - are so complex.

Kontakt: Prof. Timo Betz

09/02/26

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof. Berenike Maier

How molecular motors control the shape dynamics of bacterial colonies

Colonies and biofilms are a predominant form of bacterial life. Surrounded by an extracellular matrix, bacteria form structured communities with emergent properties that protect them from external stresses and confer tolerance to antimicrobial treatments. In this talk, I will focus on how the attractive forces between cells control these emergent properties and how they influence the fitness of bacteria. We explore these questions using the human pathogen Neisseria gonorrhoeae as a model system. In colonies, the mechanical properties are determined by type 4 pili (T4P). Over two decades, we have established biophysical and microbiological methods related to these molecular motors and developed them into a toolbox that allows us to control the mechanical properties of colonies formed by N. gonorrhoeae, including colony shape, viscosity, surface tension, local order, and sorting. A characteristic feature of this system is that the cellular network formed by T4P is inherently active and consumes energy. We recently discovered that this energy consumption creates a chemical gradient within the colonies, which in turn renders the large-scale colony morphology metastable and susceptible to an instability that drives global inversion and spreading. We identify how energy consumption, active forces, and material instabilities interact to control morphology at the colony level, providing a physical understanding of shape dynamics in living, active matter systems.

Kontakt: Prof. Jens Niemeyer / Dr. Richard Vink