URI Physics Colloquium
The URI Physics department hosts an ongoing speaker series each academic year, which features physics experts from URI and other universities, as well as scientific organizations.
During the fall and spring semesters, colloquia are held in East Hall, Room 112. Refreshments are served about half hour before each talk.
All are welcome, and there is no fee to attend.
Schedule for Fall 2025 :
Abstracts:
Modernizing K-12 Physics for the 21 st Classroom: A Shift towards Integrated STEM Education
by Emily Dare
The focus on Science, Technology, Engineering, and Mathematics education – commonly referred to as STEM education – has been lauded and critiqued since its inception in the 1990s. In more recent years and specifically within K-12 education, the term “STEM education” has become synonymous with integrated STEM education. This approach challenges the traditional, isolated approach to teaching STEM content in favor of a pedagogical shift that requires educators to consider multiple STEM disciplines simultaneously. In this, integrated STEM education puts forth a more realistic representation of how STEM content is used beyond the confines of formal education. This has major implications for K-12 students, as integrated STEM pedagogical approaches may spark and ignite interest in STEM careers, especially for individuals currently underrepresented in STEM fields, such as physics, engineering, and computer science. While most literature agrees that integrated STEM education includes the use of real-world contexts, more student-centered approaches, and intentional development of 21st century skills, defining integrated STEM education for practice has been challenging. This presentation will dive into the challenges faced by K-12 educators when it comes to integrated STEM education and provide research-based insight on how to address common challenges. This includes discussion surrounding the development of the STEM Observation Protocol (STEM-OP), which can be used to start new conversations within educational spaces to not only conduct educational research, but also lead the way in helping others develop their integrated STEM classroom practices and impact their students’ interest in STEM and STEM careers
Viewing the Universe through the Gravitational Wave Window
This month marks the 10th anniversary of the first detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO.) The culmination of decades of effort, the detection of the signal named GW150914 opened a new window through which we can explore the Universe. That first detection confirmed an essential prediction of Einstein’s General Relativity, also revealing new insights into black holes. Subsequent gravitational wave signals told us about neutron stars, synthesis of heavy elements, and star formation, and provided detailed tests of the nature of gravitation. Future observations may also shed light on the early history of the universe and perhaps eventually the nature of the Big Bang itself. The talk will explain the physics of gravitational waves, how they are detected, and prospects for the future of the field.
Bootstrapping String Amplitudes
by Grant Remmen
Is string theory unique? String amplitudes famously accomplish several extraordinary mathematical feats in order to UV-complete gravity, including exhibiting an infinite tower of spinning states and dual resonance. In this talk, I will show that string amplitudes can be uniquely bootstrapped from first principles, using techniques from the modern amplitudes program and quantum field theory to constrain the possibilities for quantum gravity from the bottom up. I will identify physical criteria for scattering amplitudes from which string theory—including its spectrum—emerges as the only consistent answer.
Leveraging numerical relativity and data-driven models for gravitational wave astronomy
by Vijay Varma
Numerical relativity simulations play a central role in gravitational-wave astronomy, as they are the only means to solve Einstein’s equations near the mergers of black holes and neutron stars and predict the gravitational wave signal. However, these simulations are too expensive for directly analyzing the signals observed by detectors like LIGO. I will talk about data-driven surrogate models that efficiently interpolate between simulations, bringing the evaluation time down from months to a fraction of a second. These models rival the simulations themselves in accuracy and bring the power of numerical relativity to gravitational wave applications ranging from black hole astrophysics to tests of general relativity. I will discuss how surrogate models are already enabling precision astrophysics, such as extracting recoil velocities from black hole mergers and improved spin measurements. Finally, I will discuss the crucial role such machine learning inspired models will play in realizing the science potential of future observatories like LISA and Cosmic Explorer.
From quantum error correction to quantum gravity — and back again
by Charles Cao
Recent advances in quantum computing have generated tremendous excitement. However, quantum bits are easily corrupted and protocols called quantum error correction are essential for maintaining quantum coherence during the computation process. Although quantum error correction may sound like a purely engineering concept, it bears a surprising connection to quantum gravity. In this talk, I will discuss how techniques developed to protect quantum information against decoherence have reshaped the way we think about spacetime and gravity. Conversely, insights from quantum gravity have inspired powerful “quantum Lego” design principles, allowing us to construct quantum error-correcting codes piece by piece, much like playing with Lego blocks.
Mathematical foundations of spatiotemporal quantum correlations
The state of a quantum system at a given time is described by a density matrix. From the density matrix, one can perform measurements to calculate expectation values of observable quantities. Is there an operator that encodes sequential measurements on a quantum system evolving from one time step to another? How is this operator different from a bipartite density operator? If one only has access to the expected values of the measurement outcomes, can we deduce whether those measurements occurred in succession or on two separate parts of a single bipartite system? Provocatively, can you tell whether there is an arrow of time based only on measurement statistics? How is the answer to this question different from what can be predicted assuming only classical probability? I will try to answer as many of these questions as time permits.
Imaging in Radiation Oncology: Diagnostic vs. Therapeutic
By Lars Ewell
Imaging constitutes an increasingly important part of radiation oncology. In distinction from radiology, where images are generally used to diagnose disease, in radiation oncology images are used to help treat disease. Computerized axial tomographic (CT) scans play a central role. Metal artifact reduction (MAR) helps to form clearer images, and cone beam CT scans assist in accurately positioning patients for treatment. Advantages and disadvantages of these different imaging modalities will be discussed.
Modernizing Quantum Thermodynamics
Sometimes our understanding of physical theories changes not because of a dramatic experimental result, but rather because of a reinterpretation of what the theory “actually means”. I’ll review two cases, statistical mechanics and quantum measurement theory, whose “modern” understanding by their practitioners is quite different from their traditional textbook explications. In statistical mechanics, I’ll review the Jaynesian interpretation of entropy and coarse-graining, and discuss the non-equilibrium results derived by Jarzynski and Crooks. In quantum measurement theory, I’ll describe the influence of the “decoherence program” in providing a clearer understanding of how coupling to an environment effectively measures a quantum system. I’ll sketch some ways in which I think combining and incorporating these understandings might help us better understand quantum thermodynamics and computation.
Time observables, relational dynamics, and quantum time dilation
General relativity demands that spacetime not be treated as a fixed background structure but as a dynamical entity. In the canonical formulation, this manifests as a Hamiltonian constraint, which appears to “freeze” physical states and gives rise to the notorious problem of time in quantum gravity: if the total Hamiltonian annihilates all states of matter and geometry, how does our familiar notion of time evolution emerge?
In this talk, I will review a class of time observables described by covariant positive‐operator‐valued measures (POVMs) [1]. These POVMs evade Pauli’s objection to the existence of a time operator, saturate the time-energy uncertainty relation, and serve as the keystone for two equivalent formulations of relational quantum dynamics [2-5]:
- The Page-Wootters formalism, in which evolution is encoded in entanglement between a clock and the rest of the system;
- The evolving constants of motion formalism, in which a family of gauge-invariant Dirac observables is constructed that evolve relationally with respect to a chosen clock variable.
Using these formalisms, I will show how unitary dynamics emerges from conditional probabilities and the kinematical structure of quantum theory alone [3]. I will also outline extensions to interacting clock systems [2] and quantum field theory [6].
Finally, I will apply this machinery to relativistic particles carrying internal degrees of freedom that function as clocks measuring their proper time [7]. Remarkably, a novel quantum time-dilation effect arises between two clocks when one is placed in a superposition of different momenta or a superposition of locations in a gravitational field. Using the lifetime of a hydrogen‐like atom as a concrete clock, I will argue that this effect is within reach of current high-precision spectroscopic experiments, thus offering a new test of relativistic quantum mechanics [8,9]. Moreover, by invoking the Helstrom-Holevo bound, I will derive a fundamental time-energy uncertainty relation linking the precision of proper‐time measurements to the clock’s rest mass [7].
References:
- Smith, A. R. H. Time in Quantum Physics. in Encyclopedia of Mathematical Physics 254–275 (Elsevier, 2025).
- Smith, A. R. H. & Ahmadi, M. Quantizing time: Interacting clocks and systems. Quantum 3, 160 (2019).
- Höhn, P. A., Smith, A. R. H. & Lock, M. P. E. Trinity of relational quantum dynamics. Phys. Rev. D 104, 066001 (2021).
- Höhn, P. A., Smith, A. R. H. & Lock, M. P. E. Equivalence of Approaches to Relational Quantum Dynamics in Relativistic Settings. Frontiers in Physics 9, 181 (2021).
- Ali Ahmad, S., Galley, T. D., Höhn, P. A., Lock, M. P. E. & Smith, A. R. H. Quantum Relativity of Subsystems. Phys. Rev. Lett. 128, 170401 (2022).
- Höhn, P. A., Russo, A. & Smith, A. R. H. Matter relative to quantum hypersurfaces. Phys. Rev. D 109, 105011 (2024).
- Smith, A. R. H. & Ahmadi, M. Quantum clocks observe classical and quantum time dilation. Nature Communications 11, 5360 (2020).
- Grochowski, P. T., Smith, A. R. H., Dragan, A. & Dębski, K. Quantum time dilation in atomic spectra. Phys. Rev. Research 3, 023053 (2021).
- Paczos, J., Dębski, K., Grochowski, P. T., Smith, A. R. H. & Dragan, A. Quantum time dilation in a gravitational field. Quantum 8, 1338 (2024).
Polynomial encoding of RNA structures reveal thermodynamic insights into R-loop formation
R-loops are a class of non-canonical nucleic acid structures that are abundant in nature and play important physiological and pathological roles. They are related to various human diseases, including cancers and genetic disorders. Recent studies suggest that both DNA sequence and topology affect R-loop formation, yet the underlying mechanisms and driving factors remain unclear. In this talk, we introduce a polynomial encoding of RNA secondary structures and a computational pipeline built on this encoding to predict R-loop formation. Our results show that this pipeline can accurately identify R-loop formation sites. Moreover, the interpretability of the polynomial encoding provides perspectives on RNA thermodynamic stability that shed light on the mechanisms underlying R-loop formation.