Events

Separating Ontology from Realist Commitment

Abstract: The web of dualities encountered in the context of string theory creates a serious problem for a realist understanding of fundamental physics: how can we understand the “real world” that would be implied by string theory, given that its dual theories suggest vastly different ontologies? A response that has gained significant traction in recent years is the common core view: identify what is invariant under duality transformations and be realist about this common core of the dual representations. In this talk, we will propose a substantially different answer: detach ontology from realist commitment and be realist about the full theory as represented by any of the duals (or, in a sense, by all duals in conjunction). On this view, an ontology characterizes an observer’s perspective as represented by a near-classical limit of the theory, while (fundamental) realist commitment points at the observer independent structure of the true theory. We argue that the separation of ontology from realist commitment not only accounts best for the message we get from string dualities but also provides an instructive perspective on realist commitment in quantum mechanics in general.

The talk is based on joint work with Gui Franzmann.

Zoom

Monday, February 2, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom

Rethinking Scientific Discovery

Scientific achievements are often framed as discoveries: prizes are awarded “for the discovery of …,” and discovery carries prestige, authority, and practical consequences for research agendas. Yet it is far from clear when a scientific discovery actually occurs. As Kuhn put it, “neither polemic nor painstaking scholarship has often succeeded in pinpointing the time and place at which a given discovery could properly be said to have ‘been made’.” This talk examines what it would mean to determine the moment of scientific discovery and to what extent such moments depend on convention. While scientific practice often treats discovery as a discrete event – something one either has or has not achieved – accounts of scientific discovery reveal its temporal and conceptual complexity. I begin with Kuhn’s distinction between that- and what-discoveries and Schindler’s refinements of this framework. To address the question of when a discovery occurs, I then draw on the recently proposed Change-Driver account of scientific discovery by Duerr and Mills, which I extend by incorporating a more explicit account of scientific problems. On this problem-oriented view, the timing of discovery is shaped by the evolving structure of problems and by shared conventions governing when a problem is taken to be adequately resolved. The account is illustrated through the cases of black holes and the Higgs boson. I conclude by adopting a cautiously pessimistic stance on the usefulness of the notion of scientific discovery itself, at least as a way of marking clear moments in scientific practice.

Zoom

Monday, February 2, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom

Quantum Mechanics of the Hartle-Hawking State

The no-boundary state in de Sitter offers a compelling framework for specifying the initial conditions of our universe. Many (but famously not all) features of the state agree beautifully with empirical observations and have served as a foundation for initial conditions in inflationary cosmology. We explore its relation to entropy puzzles in de Sitter spacetimes. We then compute the norm of the no-boundary state and show that the contributions from geometries with spherical spatial slices, including the Hartle-Hawking geometry and fluctuations around it, vanish to all loops in perturbation theory. We then discuss the resulting implications for theoretical cosmology.

Zoom

Monday, February 2, 2026 9:30 AM

Inperson
BHI Conference Room

Zoom

Monday, February 9, 2026 9:30 AM

Inperson
BHI Conference Room

The Open Systems View

A standard assumption in quantum theory is that closed, isolated systems are fundamental, while open systems are merely effective descriptions obtained by embedding them into larger closed systems. In this talk, I challenge this assumption and develop the open systems view, according to which systems interacting with their environments can themselves be treated as fundamental. The physical motivation is straightforward: in many central areas of contemporary physics—decoherence, quantum thermodynamics, cosmology, and black hole physics—strict isolation is neither realistic nor conceptually well defined. I outline a general framework for open quantum dynamics in which environmental influence is represented directly in the system’s dynamical laws, without presupposing an underlying unitary system–environment decomposition. I then connect this framework to foundational debates by showing how standard interpretations of quantum mechanics—both orthodox (Bohr-style) and (neo-)Everettian—are, despite appearances, already ontologically committed to open systems. The open systems view thus suggests a reorientation of how we think about fundamentality, interpretation, and the role of idealization in quantum theory, and offers a philosophically illuminating perspective on what quantum theory is fundamentally about.

The talk is based on joint work with Michael E. Cuffaro (MCMP).

Zoom

Monday, February 9, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom

Zoom

Monday, February 23, 2026 9:30 AM

Inperson
BHI Conference Room

Astrophysics and Cosmology with the Latest Gravitational-Wave Observations

The LIGO-Virgo-KAGRA Collaboration has observed hundreds of gravitational-wave sources to date, including mergers between black holes, neutron stars, and mixed neutron star-black holes. These neutron stars and black holes connect many astrophysical puzzles, including the lives and deaths of stars, star cluster dynamics, cosmic chemical enrichment, and the expansion history of the Universe. I will describe some recent astrophysical lessons from gravitational-wave discoveries, including evidence for the pair-instability supernova mass gap, black hole growth through repeated mergers, and implications for standard siren cosmology.

Zoom

Monday, February 23, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom

Zoom

Monday, March 2, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom

Zoom

Monday, March 16, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom

Zoom

Monday, March 23, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom

Zoom

Monday, April 6, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom

Zoom

Monday, April 13, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom

Zoom

Monday, April 20, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom

Are We There Yet? First-principles Modeling of Multimessenger Signals in the Plasma Universe

Astrophysical black holes are surrounded by accretion disks, jets, magnetospheres, and coronae consisting of magnetized relativistic plasma. They produce observable multi wavelength and multi messenger signals from near the event horizon and it is currently unclear how this emission is exactly produced. The electromagnetic radiation typically has a non-thermal component, implying a power-law distribution of emitting relativistic electrons. Magnetic reconnection and plasma turbulence are viable mechanisms to tap the large reservoir of magnetic energy in these systems and accelerate electrons to extreme energies. The accelerated electrons can then emit high-energy photons that themselves may strongly interact with the plasma, rendering a highly nonlinear system. In some cases the electromagnetic emission is accompanied by a multi messenger signal in the form of neutrinos, cosmic rays, or gravitational waves. Modeling the emitting systems necessitates a combination of magnetohydrodynamic models to capture the global dynamics of the formation of dissipation regions, and a kinetic treatment of plasma processes that are responsible for particle acceleration, quantum electrodynamics effects like pair creation and annihilation, and radiation. I will present novel studies of accreting black holes and how they radiate in regions close to black hole event horizon, using both first-principles general relativistic kinetic particle-in-cell simulations and global large-scale three-dimensional magnetohydrodynamics models. With a combination of models, I determine where and how dissipation of magnetic energy occurs, what kind of emission signatures are typically produced, and what they can teach us about the nature of black holes.

Zoom

Monday, April 27, 2026 11:00 AM

Inperson
BHI Conference Room and Zoom