Abstract: Thermally activated escape underlies a wide range of phenomena, from chemical reactions and nucleation to transport through complex free-energy landscapes. In equilibrium systems, such processes are traditionally captured by the Kramers problem, leading to exponentially long escape times -- the Arrhenius law. In this talk, I will discuss two complementary routes beyond the Kramers problem and address a central question: how robust is the Arrhenius law?
First, I will present recent results showing that introducing a time delay into the conservative force qualitatively alters the mechanism of thermal activation. Beyond a critical delay, metastable states become dynamically unstable, allowing typical thermal fluctuations to be exponentially amplified. This leads to exponentially accelerated escape rates that can exceed the free-diffusion limit and even reverse the preferred activation pathway without modifying the underlying energy landscape. More broadly, the slingshot mechanism suggests a new route for accelerating the exploration of complex free-energy landscapes. Second, motivated by the broader question of how interactions reshape activated processes, I will discuss recent work on thermal activation in interacting diffusive many-body systems. These studies establish a many-body generalization of the Arrhenius law and reveal two universality classes governing collective activation, showing an incompleteness in Langer's theory of metastability. Together, these results reveal that thermal activation is far less universal than traditionally believed: interactions reshape its collective character, while memory can eliminate its activated nature altogether.

Abstract: Understanding the formation and demographics of stellar-mass black holes is central to many areas of physics and astronomy. More than 100 million black holes are predicted to exist in the Milky Way alone. Yet, in stark contrast, only a few dozen have been identified, typically through the bright X-ray emission produced when they accrete material from a companion star.
Modern techniques based on high-precision astrometry, spectroscopy, and photometry are now revealing a new population of X-ray–quiet, or dormant, black holes. Together with systems discovered through gravitational waves, these objects show that X-ray binaries represent only the visible tip of a much larger hidden population. I will discuss emerging methods for detecting dormant stellar-mass black holes and explore what these systems teach us about stellar evolution, binary interaction, and supernova physics.

Abstract: The progenitor systems of Type Ia supernovae (SNe Ia) remain a fundamental mystery. In this seminar, we revisit the single-degenerate (SD) scenario, white dwarf accretion from a non-degenerate companion, to redefine its potential outcomes.
We demonstrate that many "standard" SD pathways suffer from premature ignition, leading to partial deflagrations and Type Iax events rather than normal SNe Ia (arXiv:2507.16907). We will present a "quiet" alternative: quiescent helium accretion. We show this mode can successfully trigger double-detonations, providing a robust path to normal SNe Ia within the SD framework (arXiv:2510.20904).
We introduce "Transformation Information," a novel morphological metric that quantifies the symmetry of supernova remnants (arXiv:2601.07913). This diagnostic allows us to link remnant complexity back to progenitor physics.

Abstract: The Poisson-Boltzmann theory, stemming from the pioneering work of Debye and Onsager,
remains the benchmark for ionic solutions and electrified interfaces. It has been instrumental
over the past century in predicting charge distributions and interactions among charged surfaces,
membranes, electrodes, macromolecules, and colloids. After reviewing the Poisson-Boltzmann
theory, I will briefly discuss several extensions and modifications applied to ions and charged
macromolecules. These ideas include the effects of dipolar solvent molecules, finite ion size, ionic
specificity, surface tension, charge regulation, and the conductivity of concentrated ionic
solutions.