Department Colloquia
The Physics Department Colloquia are held at 11:30 am on Tuesdays in Abelson 131.
Spring 2026
March 31, 2026
Francisco Villaescusa-Navarro, Simons Foundation
Abstract: Science advances by formulating and testing hypotheses, collecting and analyzing data, and drawing conclusions—yet much of a scientist’s time is spent in tasks such as coding analyses, writing and revising text, reviewing the literature, and learning new concepts. Can recent advances in AI help reclaim some of that time? In this talk, I will show how large language models and AI agents may help scientists with these tasks. I will first describe what AI agents are and their applications in science. Next, I will present Denario, a complex, publicly available, multi-AI-agent system designed to function as a research assistant. Developed and evaluated by a diverse team of scientists, mathematicians, and philosophers, Denario is an interdisciplinary tool capable of generating ideas, searching the literature, developing research plans, writing and executing code, crafting plots, drafting and reviewing scientific papers. To showcase its capabilities, I will conduct a live demonstration tasking the system with turning a dataset into ideas, codes, plots, and paper drafts in real time. I will then present and discuss some of the documents generated by Denario in disciplines such as astrophysics, biology, biophysics, biomedical informatics, chemistry, machine learning, material science, mathematical physics, medicine, neuroscience, planetary physics, and quantum physics. I’ll close by discussing how tools like Denario may help researchers accelerate scientific research and invite the audience to a broad discussion on the benefits and risks of this technology.
March 10, 2026
Paul Kushner, University of Toronto
Abstract: Global warming from anthropogenic greenhouse gas emissions presents by far the clearest signal of human influence on climate. But on top of greenhouse warming and its many impacts, anthropogenic and natural short-lived climate forcers (SLCFs) drive their own important and complex climate-change signals. SLCFs include atmospheric aerosol particulates (sulphate haze, dust, sea-salt) and reactive chemical species (methane, ozone, nitrogen oxides, etc.) that have lifetimes and mixing length scales orders of magnitude shorter than carbon-dioxide and other greenhouse gases. Their chemical reactivity, their interactions with solar-terrestrial EM radiation, their role in precipitation and cloud dynamics, and their spatial and temporal heterogeneity present a grand theoretical and modelling challenge. But research on SLCFs has advanced rapidly, which has allowed for key insights to emerge. I’ll survey work showing how the recent cleanup in aerosol pollution from East Asia has caused some global warming; what we can learn from a clean comparison between simple and complex numerical aerosol schemes; and the unexpected and disturbing short- and long-term climate impacts of fires ignited by a hypothetical nuclear war scenario.
February 3, 2026
Abstract: Only a small fraction of the collisions between ultra-relativistic heavy ions at the Large Hadron Collider (LHC) involve direct strong interactions between the nucleons of the colliding nuclei. In most cases, the nuclei interact via their electromagnetic fields in so-called ultra-peripheral collisions (UPCs), which produce an abundant rate of photon–nucleus and photon–photon collisions at the highest center-of-mass energies achievable at colliders. In this seminar, I will highlight how photon–nucleus events in UPCs can serve as a novel tool to probe the dynamics of gluons and quarks in nuclei, particularly in the small Bjorken-x regime. I will discuss recent experimental advances that have transformed the CMS detector into a high-performance instrument for studying heavy-flavor and jet production in UPCs. The seminar will present results from the first measurements of open-charm production in UPCs and provide an outlook for future analyses at the LHC in Run 3 and Run 4. The prospects for analogous measurements in electron-proton and electron-ion collisions at the Electron Ion Collider will also be discussed.
January 20, 2026
Abstract: I will describe recent results from the Dark Energy Spectroscopic Instrument (DESI) on the measurement of the cosmic distance scale with the baryon acoustic oscillation (BAO) method and its resulting implications for cosmology and dark energy. I'll start with an introduction to BAO physics and its use as a cosmological standard ruler, as well as to the design and status of the DESI project. Then I'll turn to the results from the first three years of data, which provide sub-percent measurements of cosmological distance and a tantalizing suggestion of a breakdown of the cosmological constant model. Cosmology is no longer at a moment of concordance, and I will close by attempting to summarize the current state of play.