``10,000 Einsteins: AI and the future of theoretical physics''

Machine learning has evolved from a specialized field to a foundational tool in various disciplines, including particle physics. Over the past decade, it has transformed collider physics and is beginning to influence more formal sectors of high-energy theory. An introduction to the use of machine learning in particle physics will be presented, highlighting some recent advances that the speaker has been involved in. Going forward, machine learning will play an increasingly important role in science and education, particularly with the advent of large language models. We are in the early stages of period of rapid change that has been compared to the industrial revolution, the dawn of the internet, or even the inception of writing. Some justification will be given for these bold analogies alongside speculative insights and an optimistic outlook into how machine learning might be essential for continued progress on unraveling the fundamental laws of nature.

``Visible Matter: Origin and Structure''

In this colloquium, I will discuss recent advancements in understanding the origins and structure of the 5% of visible matter in the universe through the lens of quantum chromodynamics (QCD), with a focus on nucleons and nuclei. I will present the latest experimental findings on the gravitational form factors of the proton, which, when integrated with lattice QCD studies, signal a paradigm shift in our approach to nucleon structure and enhance our comprehension of the strong force that binds nucleons and nuclei.

``Shocking tales of structure formation: Evolving galaxies and black holes in evolving environments''

Abstract: Understanding the interplay between galaxy evolution, star formation, and black hole activity from the perspective of structure formation remains one of the most fascinating challenges in modern astrophysics. On the largest scales, pairs of galaxy clusters colliding drive the growth of structure. Cluster mergers are the most energetic events since the Big Bang, which release 10^64 ergs over 1-2 billion years and produce dramatic, long-lasting effects. By bringing together panchromatic observations, I will discuss how the merger of galaxy clusters can trigger star formation and black hole activity in cluster galaxies, shape the evolution of cluster galaxies, and reverse typical environmental trends observed in relaxed clusters at low redshift. With approximately half the galaxy clusters in the local Universe undergoing mergers, this recent work has revealed gaps in our understanding of the growth of structure in the Universe and showed the potential for discovery in this understudied field. I will draw parallels between the fundamental drivers of galaxy and black hole evolution in low-redshift clusters and the processes relevant in the context of proto-clusters and high-redshift clusters, where mergers and associated non-thermal phenomena were far more common than in the nearby Universe. I will conclude by discussing how the treasure trove of cluster samples at increasingly large redshifts delivered by a new generation of instruments will help guide discoveries in the field of gas, galaxy, and black hole evolution at the epoch when structures first formed.

``Quantum Field Theory, Separation of Scales, and Beyond''

 We will review the role of Quantum Field Theory (QFT) in modern physics.  We will highlight how QFT uses a reductionist perspective as a powerful quantitative tool relating phenomena at different length and energy scales.  We will then discuss various examples motivated by string theory and lattice models that challenge this separation of scales and seem outside the standard framework of QFT.  These lattice models include theories of fractons and other exotic systems.

``Codes, CFTs, and ensemble holography''

Holographic correspondence is a duality between gravity in (d+1)-dimensional curved AdS space and non-gravitational d-dimensional QFT “living” on the boundary. More recently a substantial evidence emerged that perhaps a more fundamental version of holographic duality would be between gravity in (d+1)-dimensions and a boundary ensemble of many QFTs. Details and microscopic picture behind this duality is still largely unclear. I will show that ensemble duality emerges naturally in the context of the relation between classical and quantum codes and conformal field theories in 2d. This relation was identified back in the 90s and revised recently, leading to surprising connections with higher form symmetries and quantum information. The emerging picture is that boundary CFTs are labeled by quantum codes, such that the statement of holographic duality becomes a quantum information theoretic identity between different families of stabilizer states.   

``Pulsars as Laboratories for Fundamental Physics"

Pulsars — rapidly rotating neutron stars emitting regular electromagnetic pulses — are pivotal in astrophysical tests of fundamental physics. Their pulse timing precision allows the detection of subtle disturbances from gravitational waves, while their extreme density offers unique insights into theories beyond the Standard Model, especially those predicting baryon number violation (BNV).  Stringent constraints on BNV, arising from its non-observation in experiments, motivate the search for its astrophysical consequences. This talk examines how slow BNV processes, leading to quasi-equilibrium evolution, influence pulsar orbital and spin dynamics. Observations of binary pulsar orbital periods, coupled with the effects of dense matter in neutron star cores, can place severe constraints on BNV. We propose that BNV in pulsars could manifest as anomalies in the second derivative of the spin frequency, transitions between states of spinning down and up, and a spectrum of braking indices. The talk concludes by exploring the potential for detecting these effects, particularly in the context of advancements in pulsar timing arrays and the broader implications for our understanding of fundamental physics.

``Pulsed, Polarized and Sliced – Fundamental Ingredients in Neutron Precision Physics"

The neutron represents a versatile tool in the realm of fundamental particle physics at low energies. In my research group, we focus on the development of novel precision devices and experiments with the goal to search for signals of new physics beyond the standard model of particle physics. In this seminar, I will introduce a few such activities currently pursued at the University of Bern and carried out at national and international neutron research centers. The projects comprise the hunt for a neutron electric dipole moment using a pulsed beam, the search for axion-like particles, and the development of a high-sensitivity grating interferometer to measure the neutron electric charge.

``Opening up the Gravitational Wave Spectrum''

The historic discovery of gravitational waves by LIGO has initiated a new era of astronomy, permitting us to observe the universe through new eyes. LIGO is sensitive to gravitational waves at frequencies above 40 Hz. Much like the case of electromagnetism, there is a strong science case to observationally probe other parts of the gravitational wave spectrum. Significant advances on this front have been made in the mHz band by the LISA collaboration and the nHz range by the NanoGRAV collaboration. How might be probe other gravitational wave frequencies? In this talk, I will discuss the use of atom interferometers to probe gravitational waves in the 1 Hz band. I will also explore the potential use of asteroids as test masses to detect gravitational waves at micro Hz frequencies and the possible use of astrometry in the nHz - micro Hz regime.