Sommerfeld Theory Colloquium (ASC)

If systems characterized by slow (algebraic) relaxation are prepared in an out-of-equilibrium

initial state, one can observe a "physical aging regime" in the ensuing approach to equilibrium

that is governed by broken time translation invariance and non-trivial, often universal scaling laws. Dynamical systems near a critical point constitute prototypical and now well-understood

examples. Indeed, measuring critical exponents in the intermediate aging rather than the asymptotic stationary temporal regime is now a standard numerical tool. In this talk, I will first apply these concepts to simple driven lattice gases that relax towards non-equilibrium stationary systems displaying generic scale invariance. The expected simple aging behavior in the two-time density auto-correlation function is verified through Monte Carlo simulations in one, two, and three dimensions. Next I shall address the continuous non-equilibrium phase transition in driven Ising lattice gases in two dimensions. Whereas the temporal scaling of the density auto-correlation function in the non-equilibrium steady state does not allow a precise measurement of the associated critical exponents, these can be accurately determined from the aging scaling of the two-time auto-correlations and the order parameter evolution following a quench to the critical point. In the second part of the talk, I will present numerical results for the non-equilibrium relaxation kinetics of interacting magnetic flux lines in disordered type-II superconductors at low temperatures and low magnetic fields, represented by means of a three-dimensional elastic line model. Investigating the vortex density and height auto-correlations as well as the flux line mean-square displacement allows us to carefully disentangle different relaxation mechanisms (e.g., vortex line fluctuations and positional relaxation), and to assess their relative impact on the kinetics of dilute vortex matter at low temperatures. We observe the emergence of genuine glassy dynamics, caused by the competing effects of vortex pinning and long-range repulsive interactions between the flux lines. We contrast the effects of random point-like pinning centers and correlated columnar defects. We also compare data from Monte Carlo simulations with results from Langevin molecular dynamics.

The central mystery in quantum matter is the general nature of mat- ter formed from fermions. The methods of many body quantum physics fail and one can only rely on the phenomenological Fermi- liquid and BCS theories. However, in heavy fermion systems and cuprates one deals with non Fermi-liquid quantum critical metals, and to understand the superconductivity one needs to understand these normal states first. Remarkably, it might well be that the mathematics of string theory is capable of describing such states of fermion matter. The AdS/CFT correspondence translates this problem into an equivalent general-relativity problem involving the propagation of classical fields in an Anti-de-Sitter space-time with a black hole in its center. This development started with the demon- stration that AdS/CFT predicts correctly the low viscosity of the quark-gluon plasma of the Brookhaven heavy ion collider. In 2007 it was realized that it could have relevance to high Tc superconductors but only last year the focus shifted to the way AdS/CFT processes fermions, creating much excitement: it appears that both emergent heavy Fermi-liquids and non Fermi-liquids can be gravitationally encoded, as well as holographic superconductors having suggestive traits in common with the real life high Tc variety.

The Sun is a most remarkable object: it is filled with vibrantly evolv- ing magnetic fields, well-mixed hierarchically-arranged turbulent con- vective cells, and also poorly-mixed sunspots that persist with im- punity. Solar variability has direct consequences for the earth and space weather, an important reason to develop an appreciation for the physics of the solar cycle (dynamo).

Direct observation of the solar subsurface is impossible due to the high degree of optical scattering by the partially ionized plasma that inhabits the near-surface layers of the Sun. The deepest part of the Sun visible to us, known as the photosphere (also the solar surface), appears as a roiling, turbulent, radiative, magnetized, convecting plasma. At first glance, it would seem therefore that subtle ques- tions relating to the subsurface constitution of the Sun seem com- pletely unanswerable and the interior properties unknowable. How- ever, analogous to geoseismology, a great deal can be gleaned about the internal structure and dynamics of the Sun by carefully observ- ing and analyzing the surface wavefield. This has been made possible over the last few decades through the development and application of techniques of helioseismology.

In this talk I will outline some of the major results in this area over the last two decades and discuss some recent developments pertaining to the properties of turbulence in the deep-convection zone of the Sun.

In connection with the existing and forthcoming missions dedicated to search for cosmic antimatter, the models of baryogenesis leading to an efficient creation of astronomically large antimatter objects are reviewed. It is argued that such objects may be abundant in the universe and even in the Galaxy. Their observational signatures and the prospects for discovery are discussed.

The Planck mission was launched successfully in May last year. I will give a summary of the scientific aims of the Planck mission and a brief overview of its current status. I will also place the Planck mission in context with ground and suborbital CMB experiments and other probes of early universe cosmology.

Based on a calculation of the shear viscosity η and the entropy density s of certain strongly coupled field theories via the AdS/CFT-correspondence, Kovtun, Son and Starinets conjectured that their ratio is bounded below by the universal number ħ/4πkB, a bound that appears to hold for all existing fluids. The substances that come closest to being perfect in the sense of a minimum value of η/s are the quark gluon plasma and ultracold atoms at infinite scattering length, the so called unitary Fermi gas. The talk provides an introduction to the origin and interpretation of this bound from a simple physics perspective. Moreover, quantitative results for η/s are presented in the normal phase of the unitary Fermi gas. They are consistent with the Kovtun, Son and Starinets bound and are also in good agreement with experiments.

One of the great insights of cryptography and computational complexity is the notion of computationally-bounded algorithms, which allow us to reason about properties that would otherwise be impossible to achieve. Could these ideas also be relevant to quantum information and quantum mechanics? In this talk, we discuss how computational thinking changes the landscape of quantum cryptography: What primitives can we construct, how definitions change, and what are the outstanding open problems. If time permits, we will also discuss new foundational questions on quantum information, motivated by cryptographic applications.

All the information we will ever obtain from the early universe is imprinted in the spatial correlations of primordial fluctuations at the hot Big Bang. I will explain how an influx of ideas from various areas of fundamental physics is providing us with new conceptual and practical tools to decode the physics of these primordial fluctuations. A thorough understanding of the fluctuations will give us insight into particle physics at high energies and may provide a window into the nature of spacetime itself.

The gravitational two-body problem has been fundamental to physics since Newton's time. With the advent of gravitational wave astronomy and the anticipated third generation of gravitational wave detectors in the 2030s, there is an increasing need for high-precision predictions from Einstein's theory of gravity regarding the encounters of black holes and neutron stars in our universe. Fascinatingly, perturbative quantum field theory methods developed for high-precision predictions of elementary particle scattering at the LHC have proven remarkably efficient for this classical physics problem. This unexpected connection has led to inspiring synergies between collider and gravitational wave physics. In my talk, I will present our approach using a worldline quantum field theory inspired by string theory, which has emerged as the most efficient tool for quantifying the scattering of spinning black holes. We have achieved highest-precision perturbative results for the scattering angle, radiated energy, and recoil of such black hole encounters at the fifth order in Newton's gravitational coupling G. Our four-loop calculations have revealed a new class of mathematical functions related to Calabi-Yau manifolds, previously studied only in mathematics and string theory compactifications, appearing for the first time in a physical context: The radiated energy in gravitational waves at NNNNLO perturbation theory.

We present Denario, an AI multi-agent system designed to be a scientific research assistant. Denario can perform many different tasks, such as generating ideas, checking the literature, developing research plans, writing and executing code, making plots, and writing a scientific paper. Denario is built as a modular system, and therefore, can perform either very specific tasks, such as generating an idea, or carrying out end-to-end scientific analysis using cmbagent as a deep-research backend. In this talk, we describe Denario and its modules in detail and illustrate its capabilities by presenting multiple AI-generated papers generated by it. These papers cover many scientific disciplines, such as astrophysics, biology, biophysics, biomedical informatics, chemistry, material science, mathematical physics, medicine, and planetary science. Denario can also perform research combining ideas from different disciplines, and we illustrate it by showing a paper that applies methods from quantum physics and machine learning with astrophysical data. We publicly release the code at https://github.com/AstroPilot-AI/Denario. A Denario demo can also be run directly on the web at https://huggingface.co/spaces/astropilot-ai/Denario, and the full app is deployed on the cloud.