Sommerfeld Theory Colloquium (ASC)

Latest Episodes:

Black Holes, Quantum Information, and Unification Jun 10, 2026

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The study of black holes has revealed a deep connection between quantum information and spacetime geometry. Its origin must lie in the quantum theory of gravity, which offers a valuable hint in our search for a unified theory. Precise formulations of this relation recently led to new insights in Quantum Field Theory, some of which have been rigorously proven. An important example is our discovery of the first universal lower bound on the local energy density. The energy near a point can be negative but it is bounded below by a quantity related to the information flowing past the point.

Quantum simulators for fundamental physics Jun 10, 2026

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The dynamics of the early universe and black holes are fundamental reflections of the interplay between general relativity and quantum fields. The essential physical processes occur in situations that are difficult to observe and impossible to experiment with: when gravitational interactions are strong, quantum effects are important, and theoretical predictions for these regimes are based on major extrapolations of laboratory-tested physics. We will discuss the possibility to study these processes in experiments by employing analogue classical/quantum simulators. Their high degree of tunability, in terms of dynamics, effective geometry, and field theoretical description, allows one to emulate a wide range of elusive physical phenomena in a controlled laboratory setting. We will discuss recent developments in this area of research.

Deciphering the Beginning Jun 10, 2026

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The cosmic microwave background contains a wealth of information about cosmology as well as high energy physics. It tells us about the composition and geometry of the universe, the properties of neutrinos, dark matter, and even the conditions in our universe long before the cosmic microwave background was emitted. After a general introduction, I will turn to the search for primordial gravitational waves with CMB observations and gravitational wave observatories.

Limits of strong CP Jun 10, 2026

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Quantum mechanical potentials with multiple classically degenerate minima lead to spectra that are determined by the pertaining tunneling amplitudes. For the strong interactions, these classical minima correspond to configurations of a given Chern-Simons number. The tunneling amplitudes are then given by instanton transitions, and the associated gauge invariant eigenstates are the theta-vacua. Under charge-parity (CP) reversal theta changes its sign, and so it is believed that CP-violating observables such as the electric dipole moment of the neutron or the decay of the eta-prime meson into two pions are proportional to theta. Here we argue that this is not the case. This conclusion is based on the assumption that the path integral is dominated by saddle points of finite action and fluctuations around these. In spacetimes of infinite volume, this leads to the requirement of vanishing physical fields at the boundaries. For the gauge fields, this implies topological quantization corresponding to homotopy classes for all integers. We consequently calculate quark correlations by first taking the spacetime volume to infinity and then summing over the sectors. This leads to an absence of CP violation in the quark correlations, in contrast to the conventional way of taking the limits the other way around. While there is an infinite number of homotopy classes in the strong interactions, there is only a finite number of classical vacua for quantum mechanical systems. For the latter the order of taking time to infinity and summing over the transitions is therefore immaterial.

Emergence of geometry and meaning, through gauge and strings dynamics Jun 10, 2026

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I will discuss the statistical physics of random growth processes which, on the one hand, model the non-perturbative gauge dynamics, emergence of space geometry in string theory on the other, yet could also model the evolution of language(s).

Fantastic periods and where to find them Jun 10, 2026

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After a short introduction to the swampland program and the challenges one faces in explicit tests of some conjectures, this talk will focus on the computation of periods and their application to the swampland program. A detailed understanding of periods allows to answer questions about the existence of solutions or the finiteness of the string landscape, as well as explicit constructions of models. Moreover, applications of periods outside of string compactifications are discussed, such as the computation of Feynman integrals, the tameness of QFTs and the appearance of periods in many other physical systems.

Interplay between mechanics and chemistry in living systems Jun 10, 2026

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Living systems interact with their environment by exerting mechanical forces and exchanging chemical substances. By fueling nonequilibrium reactions and driven molecular transport, cells dynamically create internal protein patterns (symmetry breaking) which, in turn, control cell mechanics and force generation. Here, we discuss some examples and consequences of such a mechanochemical coupling, ranging from proteins that cooperatively bind and bend membranes, to protein patterns that elicit nonspecific cargo transport via driven diffusive fluxes on planar membranes. Finally, on much larger scales, we discuss how active cells can control tissue shape via their broken symmetry and, specifically, through their orientation.

Chemically Active Wetting Jun 10, 2026

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Wetting of liquid phases, such as water drops condensing at the surface of plant leaves, is ubiquitous in our daily life. Interestingly, the physics of wetting also plays a crucial role in our cells. Droplets composed of proteins can wet specific target sites in living cells and locally enrich biomolecules for specific chemical processes. Many droplet-forming proteins can also bind to membrane surfaces. Binding in cells is often chemically active since it is maintained away from equilibrium by supplying energy and matter. This non-equilibrium setting suggests a plethora of physical phenomena of soft condensed phases at biological interfaces. To investigate such phenomena, we derive the non-equilibrium thermodynamic theory of active wetting. By means of this theory, we show that active binding significantly alters the wetting behavior leading to non-equilibrium steady states with condensate shapes reminiscent of a fried egg or a mushroom. We further show that condensate shapes can switch upon changing the strength of active binding. The origin of such anomalous condensate shapes can be explained by an electrostatic analogy, where binding sinks and sources correspond to electrostatic dipoles along the triple line. This analogy suggests a general analogy between chemically active systems and electrodynamics.

The asymptotic structure of gravity at spatial infinity (D=4 and D>4) Jun 10, 2026

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The asymptotic structure of gravity in the asymptotically flat case will be described in four and higher spacetime dimensions by making central use of the Hamiltonian formalism. Special emphasis will be paid to the case D=5. How the relevant infinite-dimensional asymptotic symmetry group (BMS group) emerges at spatial infinity will be explained. Non-linear structures which appear in five (and higher) spacetime dimensions will be discussed.

The mathematics behind Feynman integrals Jun 10, 2026

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Feynman integrals are indispensable for precision calculations, not only for high-energy particle physics experiments, but also for example for QED precision experiments at lower energies or precision studies in gravitational wave physics. In recent years there has been a significant progress in our abilities to compute Feynman integrals, revealing a rich and fascinating mathematical structure, relating Feynman integrals to (algebraic) geometry. In this talk I will review these recent developments.