Department of Physics, University of Toronto

Read the latest updates at UofT Physics and explore our upcoming events. The departmental spring newsletter is now live: https://uoft.me/springnewsletter2026

Colloquium: Time’s Second Arrow: Evolution, Order, and a New Law of Nature

Robert Hazen, Carnegie Science

A pervasive wonder of the natural world is the evolution of varied systems, including stars, planets, minerals, and life—all of which have increased in diversity and patterning over deep time. However, no law of nature describes and explains, much less quantifies and predicts, the behavior of complex evolving systems. Accordingly, our group has proposed a new law of nature, the “law of increasing functional information,” that we apply to the evolution of both abiotic systems (isotopes, minerals) and life. This postulated increase in functional information represents a second arrow of time—one that is consistent with the increase in entropy (the first arrow of time) but is not derivable from the laws of thermodynamics. This concept is now being applied and tested by other groups in fields as wide-ranging as the evolution of languages, the behavior of AI systems, the seasonal variations of soil microbiomes, and the search for new cancer therapies. Mineral evolution, which explores the diversification of Earth’s mineral kingdom on more than 4.5 billion years, is an especially revealing test case of this proposed law of nature.

Thursday, April 2, 2026
3:10 p.m. EST
Room 102
McLennan Physical Laboratories
60 St. George Street, Toronto, Ontario

Coffee and cookies will be served in the Physics Lounge at 2:45 p.m.
https://www.physics.utoronto.ca/news-and-events/events/colloquium/

MathMatize: a useful tool for making better formative assessments in physics courses

Brian Wilson, UofT Physics

Thursday, March 26, 2026
3:10 p.m. EST, Room 102
McLennan Physical Laboratories
60 St. George Street, Toronto, Ontario

Formative assessments are supposed to provide students with crucial feedback about their learning and progress in a course. Ideal formative assessments are low-pressure, challenging tasks which are graded and returned quickly. Unfortunately, large class sizes make it difficult to provide timely feedback via traditional homework assignments.

In this colloquium I will describe my use of the MathMatize app in the context of a large, second-year electricity and magnetism course to create more meaningful formative assessments. Similarly to other common in-class response tools (clickers, Learning Catalytics or Top Hat), it can be used to create simple multiple-choice or fill-a-blank questions. It's most powerful feature, however, is an ability to fully understand mathematical equivalence, allowing implementation of formulae. This allows for practising symbolic notations on various levels, helping students develop formal mathematical competencies required in upper-level courses.

If you bring an electronic device with internet access and a browser, there will be sample questions to try out for yourself!

Coffee and cookies will be served in the Physics Lounge at 2:45 p.m.
https://www.physics.utoronto.ca/news-and-events/events/colloquium/

The presentation will also be streamed on Zoom where you can view it on your own device.

To join via Zoom, please use this link:
https://us06web.zoom.us/j/84634223695?pwd=R29qMlF3OFA2QVY0S1N5Q2R5Z1JyUT09
Webinar ID: 84634223695
Passcode: 122753

THIS EVENT IS NOW CANCELLED!!!
Colloquium: When the planet becomes the dataset: A paradigm shift in illuminating Earth’s dynamic interior
Presenter: Edward Garnero, Arizona State University

Thursday, March 19, 2026
3:10 p.m. EST
Room 102
McLennan Physical Laboratories
60 St. George Street, Toronto, Ontario

For decades, the growth of freely available seismic data has led to key discoveries about earthquakes and Earth’s properties. From crust to inner core, seismologists have sharpened the focus on key structures that enable inference on Earth’s internal dynamics, composition, and evolution. This presentation will address the continued increase in availability of data, the challenges to find, collect, and store them, and our efforts to collect every relevant seismogram on Earth, for improved Earth imaging.

Why care? While seismic imaging reveals Earth interior phenomena at the best possible resolution, most structures lack enough constraints to definitively understand their nature and origin. This includes massive lower mantle continental-sized Large Low Velocity Provinces (LLVPs), which are situated away from subduction (places where tectonic plates fall into the interior) and generally underly hot spot volcanoes. Sometimes over 1000 km thick, seismic evidence suggests LLVPs are compositionally different from the surrounding mantle. But what are they? And how well are they really imaged? At smaller scales Ultra-Low Velocity Zones (ULVZs) are thin (10’s of km) structures right at the CMB, probably partially molten and possibly also compositionally distinct. How do these structures relate to Earth’s formation, evolution, and mantle dynamics? What are they made of? How well are we seeing them? These questions and others require seismic analyses with the best and most abundant data possible. They require multidisciplinary approaches with mineral physicists, geodynamicists, geochemists, tectonicists, and others.

But how can we sharpen the focus? In this presentation I will highlight our inherent spatial and temporal biases in seismic imaging of these and other structures, where uneven sampling of Earth figures prominently in the challenges. To mitigate these, I’ll present our ongoing effort to bring big data to the table, with a focus on using every available seismogram, combined with measurements of unutilized seismic reverberations that sometimes echo and reflect their way around the entire planet. I’ll briefly mention the potential for machine learning and AI to uncover subtle waveform phenomena. Earth’s resonances and reverberations hold profound potential for advancing our understanding of planetary formation and evolution.

Coffee and cookies will be served in the Physics Lounge at 2:45 p.m.
https://www.physics.utoronto.ca/news-and-events/events/colloquium/

The presentation will also be streamed on Zoom where you can view it on your own device.

To join via Zoom, please use this link:
https://us06web.zoom.us/j/84634223695?pwd=R29qMlF3OFA2QVY0S1N5Q2R5Z1JyUT09
Webinar ID: 84634223695
Passcode: 122753

Colloquium: A decade of black hole observations with gravitational waves
Katerina Chatziioannou, California Institute of Technology

Thursday, March 12, 2026
3:10 p.m. EST, Room 102
McLennan Physical Laboratories, 60 St. George Street, Toronto, Ontario

In just ten years, gravitational-wave astrophysics has progressed from a young, promising field to one with an observational yield of hundreds of signals. Spearheaded by the twin LIGO detectors, the most sensitive detectors to date, observations of merging black holes have revealed a diverse population of stellar-mass objects. These discoveries have reshaped our understanding of black hole demographics and have enabled unprecedented tests of gravity in the strong-field, highly dynamical regime. In this talk, I will briefly review key results on black holes obtained from hundreds of gravitational-wave detections. I will then focus on GW250114, the “decadal” signal of gravitational-wave astronomy that showcases the promise of the upgraded LIGO detectors for probing the fundamental nature of black holes and gravity. GW250114’s exceptionally high signal-to-noise ratio enabled the direct observation of multiple quasinormal modes in the ringdown of the remnant black hole. This landmark measurement allowed us to test the no-hair theorem, which links the mode frequencies to the Kerr spectrum, as well as Hawking’s black hole area law, which states that the total horizon area of black holes cannot decrease.


Coffee and cookies will be served in the Physics Lounge at 2:45 p.m.
https://www.physics.utoronto.ca/news-and-events/events/colloquium/

The presentation will also be streamed on Zoom where you can view it on your own device.
To join via Zoom, please use this link:
https://us06web.zoom.us/j/84634223695?pwd=R29qMlF3OFA2QVY0S1N5Q2R5Z1JyUT09
Webinar ID: 84634223695
Passcode: 122753

Lessons from smart slime
Karen Alim, Technical University of Munich
Thursday, March 5, 2026, 3:10 p.m. EST

Room 102, McLennan Physical Laboratories
60 St. George Street, Toronto, Ontario
Coffee and cookies will be served in the Physics Lounge at 2:45 p.m.
https://www.physics.utoronto.ca/news-and-events/events/colloquium/

Propagating, storing and processing information is key to take smart decisions – for organisms as well as for autonomous devices. In search for the minimal units that allow for complex behaviour, the slime mould Physarum polycephalum stands out by solving complex optimization problems despite its simple make-up. Physarum’s body is an interlaced network of fluid-filled tubes lacking any nervous system, in fact being a single gigantic cell. Yet, Physarum finds the shortest path through a maze. We unravel that Physarum’s complex behaviour emerges from the physics of active flows shuffling through its tubular networks. Flows transport information, information that is stored in the architecture and mechanical state of the network. Thus, tubular adaptation drives processing of information into complex behaviour. Taking inspiration from the mechanisms in Physarum we outline how to embed complex behaviour in active microfluidic devices and how to program human vasculature.

The presentation will also be streamed on Zoom where you can view it on your own device.
To join via Zoom, please use this link:
https://us06web.zoom.us/j/84634223695?pwd=R29qMlF3OFA2QVY0S1N5Q2R5Z1JyUT09
Webinar ID: 84634223695
Passcode: 122753

Colloquium:
A nonconventional p-wave (alter)magnet
Riccardo Comin, MIT
Thursday, February 26, 2026, 3:10 p.m.

Altermagnets are a new class of magnetic materials that combine aspects of ferromagnets and antiferromagnets, possessing zero net magnetization like antiferromagnets but exhibiting (potentially large) spin splitting of the electronic bands and anomalous Hall responses like ferromagnets. Recent research has focused on magnetic systems with odd-parity spin splitting of nonrelativistic origin (p-wave magnets), which are promising for spintronic applications. Symmetry considerations suggest the possibility of coupling altermagnetism with ferroelectricity in polar chiral magnets, potentially allowing for novel mechanisms for electric-field control of magnetism.

Recent theoretical studies have identified helical magnets as a platform to realize p-wave magnetism. One such material is nickel iodide (NiI2) is a van der Waals magnetic insulator and multiferroic when in its chiral magnetic phase (T < 59 K). The spin helices that characterize this phase breaks inversion symmetry, leading to a spin-induced improper charge polarization of purely electronic origin. I will introduce the intriguing properties of this material in the bulk and down to the two-dimensional limit, where it was shown that the multiferroic state is robust even in a single-layer-thick sample. I will then focus on more recent work characterizing the nonrelativistic spin splitting of electronic bands in NiI2, and its connection to symmetry and chirality. I will present a demonstration of the electrical (voltage-based) switching of chirality and consequent reversal of the momentum-space spin polarization. I will conclude with an outlook for potential applications of spin-chiral multiferroics for information storage.


Room 102, McLennan Physical Laboratories
60 St. George Street, Toronto, Ontario
Coffee and cookies will be served in the Physics Lounge at 2:45 p.m.
https://www.physics.utoronto.ca/news-and-events/events/colloquium/

🎇Colloquium:
Two-Eyed Seeing”: Dynamical evolution across galactic scales
Kathryne Daniel, University of Arizona

Thursday, February 12, 2026, 3:10 p.m.
Room 102, McLennan Physical Laboratories, 60 St. George Street

“Two-Eyed Seeing,” a concept introduced by Mi’kmaq elder Albert Marshall, describes the richer understanding that comes from drawing on both Indigenous knowledge systems and Western science. This talk will explore how that principle can inform our approach to astrophysics, beginning with the longstanding challenge of disentangling the many dynamical drivers of disk galaxy evolution. Disks evolve within diverse environments set by their merger histories and halo geometries. Resonances from bars and spiral arms reshape disk morphology while also continually reorganizing stellar populations, star clusters, and exoplanet systems. I will present a collection of methods that allow us to deconstruct some of these overlapping processes, link parsec-scale dynamics to kiloparsec-scale morphological evolution, and identify observational clues to the dynamical history of the Milky Way. Time permitting, I will touch on the status of the next generation gravitational wave observatory in the US, Cosmic Explorer. In particular, how our approach to site selection embodies two-eyed seeing and why our approach is critically important to the future of big science.


Coffee and cookies will be served in the Physics Lounge at 2:45 p.m.
https://www.physics.utoronto.ca/news-and-events/events/colloquium/

The presentation will also be streamed on Zoom where you can view it on your own device.

To join via Zoom, please use this link:
https://us06web.zoom.us/j/84634223695?pwd=R29qMlF3OFA2QVY0S1N5Q2R5Z1JyUT09
Webinar ID: 84634223695
Passcode: 122753

This week's Colloquium:
Physics for AI for Physics

Yonatan Kahn, University of Toronto

Thursday, February 5, 2026, 3:10 p.m.
Room 102, McLennan Physical Laboratories
60 St. George Street

In just the past decade, neural networks have made stunning progress on tasks long thought to be exclusive to humans, but the "hard problem" of artificial intelligence remains: why does a trained neural network give the output it does? In this talk, I will show that an approach to studying neural networks which borrows techniques and perspectives from physics can make quantitative progress on at least three important facets of this problem: what happens during training, why performance appears to scale predictably and robustly with the amount of training data, and how the structure of data affects both training and performance. I will argue that physics provides a suite of theoretical tools naturally suited for studying neural networks, and how the topology and geometry of collider physics data may be used as a testbed for theories of machine learning relevant for data “in the wild”. Armed with this improved understanding beyond the “black box” of AI, we can put AI tools to better use to discover more about the physics of our universe.

Coffee and cookies will be served in the Physics Lounge at 2:45 p.m.
https://www.physics.utoronto.ca/news-and-events/events/colloquium/

The presentation will also be streamed on Zoom where you can view it on your own device.
To join via Zoom, please use this link:
https://us06web.zoom.us/j/84634223695?pwd=R29qMlF3OFA2QVY0S1N5Q2R5Z1JyUT09
9s

UPCOMING EVENT:

J. TUZO WILSON LECTURE
From the Globe to Plants: Measuring Carbon Dioxide Fluxes from Space
Isabel Bader Theatre, 93 Charles St. West, Toronto

Tuesday Feb 24th, 2026, 7:30 pm
Refreshments Afterwards

https://tuzowilson.physics.utoronto.ca/
Register: https://forms.office.com/r/knLun8VDNw

Stay safe and enjoy the snow! ⛄⛄❄️