The department offers a physics colloquium every Friday. Researchers from outside the College are invited to talk about their work, students discuss their summer research projects and their senior-exercise topics, and alumni share their latest exploits. Check regularly for upcoming talks. 

Spring 2022 Physics Colloquiums

In the spring semester, several students majoring in physics pursued Independent research projects with a faculty advisor. The research topics spanned a wide range. These students will present their work at a poster session during the regular departmental colloquium hour. Come support your fellow physics students!

The poster session will be held on Friday, May 6, from 12 to 1 p.m. You can come see the projects, visit with our physics students and enjoy lunch. We hope to see you then!

Two of our honors physics students will be presenting their Honors Thesis on Friday, April 29. Please come celebrate and support Mary Gerhardinger and Ericka Florio as they complete the final steps to graduate with honors.

Mary's presentation will be "Numerical Simulations of Nonlinear Physics in the Universe." The contemporary model of cosmology contains several problems, with both the theories that compose it as well as the methods used to perform it. In this talk, I will address three such outstanding questions — the Hubble Tension, the formation of primordial black holes in General Relativity, and the Well-posedness problem in a formulation of Beyond-Einstein Gravity. I present the novel work that I have done investigating these issues and discuss my results. We conclude that we must do the nonlinear problem, no matter how difficult.

Ericka's presentation will be "Simulating the High-Energy Universe, from the Big Bang to Black Holes." The study of high energy systems in cosmology remains one of the most exciting avenues to probe beyond-SM physics. In this talk, I present the results of three research projects I have undertaken in Kenyon's cosmology lab, all centered around modeling high-energy phenomena using GABE, our nonlinear scalar field evolver. I first present our findings which show that a nonlinear Early Dark Energy field evolved alongside matter and radiation fluids generates a measure for the ISW above current sensitivity levels. I then show how quartic models of the inflaton undergo parametric resonance, but that this resonance is not powerful enough to produce primordial black holes. Finally, I will show how the inclusion of fully-nonlinear interaction terms may affect the outgoing form of a scalar plane wave scattered off of a black hole in trumpet coordinates.

Mary's presentation will be at 12:10 p.m. and Ericka's presentation will be at 3:40 p.m. Join us then to hear these exciting discussions.

 

Xuemei Cheng, professor of physics at Bryn Mawr College, will be joining us to speak about the discovery of a spin memory effect in skyrmions that stems from their topology.

Magnetic skyrmions are small swirling spin textures that can form in materials with strong Dzyaloshinskii–Moriya interactions (DMIs). The nontrivial topology provides stability and resistance to annihilation that make skyrmions attractive for applications. Recently, antiferromagnetically (AFM)-coupled skyrmions have been of increasing interest because they are more attractive candidates for developing spin-based information storage and sensing devices with higher stability, speed and capacity, as compared to ferromagnetic skyrmions. 

In this talk, I will report the discovery of a spin memory effect in skyrmions that stems from their topology. We have created stable antiferromagnetically coupled bubble skyrmion pairs at room temperature in [Co/Gd/Pt]10 multilayered films that undergo a spin reorientation transition (SRT) as temperature is decreased. Photoemission electron microscopy imaging shows that these bubble skyrmions evolve into dramatically different in-plane spin textures through the SRT and reform completely on warming back up. Simulations demonstrate that DMIs play a key role in this spin memory effect, and furthermore reveal that the topological charge is preserved throughout the dramatic spin texture rearrangement and recovery. The discovered spin memory effect provides a means to encrypt and recover spin information that could serve as the basis for a magnetic analog of invisible ink, and it may also inspire new approaches to controlled skyrmion formation and manipulation for logic applications.

Join us on Friday, April 15 from 12 to 1 p.m. in Hayes 211/213 to hear this exciting presentation. Lunch is available to guests before the lecture in Hayes 201. We hope to see you then!

Andrew Heckler, professor of physics at OSU, will discuss the traditional system of grading in STEM education and its effect in education.

Grades and grading scales have been in practice in schools for as long as we can remember. Yet, how well have these techniques worked, and do they really reflect fairness in understanding how well students understand the subject matter?

Heckler, professor of physics at the Ohio State University, will discuss the idea that traditional, high stakes testing and grade curving are two common practices in STEM education that are used not only because they are regarded as efficient solutions to the complex problem of educating large numbers of students, but, at least anecdotally, they also seem to be aligned with assumptions and perspectives of fairness, rigor, and academic integrity by many instructors in the physics community. Still, there are many problems with these two practices — some that have been discussed since the early part of last century — that challenge the assumptions of fairness, rigor, and integrity, and reorient us towards our core educational goals and values. Heckler will present data from a large sample of physics student grades from OSU to bring up these issues again, perhaps with some new insights and perspectives that can help to inspire the STEM community to think of better solutions.

Join us on Friday, April 8, from 12 - 1 p.m. in Hayes 211/213 to hear this exciting presentation. Lunch will be available in Hayes 201 before the presentation from 11:50 a.m. to 12:15 p.m. We hope to see you then!

Who plans all the physics trips? Who are the people that organize physics t-shirts? Why were there random packets of a fun dip in my cubby on Valentine’s Day? To get these answers and more please join us on April 1 as the Society of Physics Students hosts a special colloquium for Bring Your Child to Work Day.

This event is open to all children and parents across all departments on campus. We will give a brief presentation (we mean brief, no April Fools here) welcoming our visitors, introducing your officers, and announcing this year’s t-shirt design winner. Afterward, please join us in enjoying some fantastic physics alongside the children of the department. From catapulting objects at high velocities, to cooling liquids to -300℉, the physics department will gather as a community to celebrate the awesomeness of the subject that brings us all together. To steal our predecessor's words, “It’s Physics Time!”

Join us on Friday, April, 1 from 12 - 1 p.m. in Hayes 211/213 to celebrate Bring Your Child to Work Day with the Physics Department! Pizza will be available before the activities in Hayes 201 from 11:50 to 12:15. Grab a slice or two and enjoy some fun physics!

Dr. Katharine E. Jensen, assistant professor of physics and pre-engineering advisor at Williams College, will present a talk on transitions in leaking fluid and topics related to wetting and adhesion of soft materials. 

Small fluid leaks are common — and frequently troublesome. We often consider how to stop a leak, but here we ask a different question: how might a leak stop itself? We use simple experiments and high-speed imaging to study flow transitions in leaking fluid flows from jetting to dribbling to spontaneous arrest. It turns out that a self-stopping leak behaves as a “damp” harmonic oscillator, and we can understand the process of spontaneous arrest with an energetic analysis that depends on the leak geometry, driving pressure, surface tension, and wettability of the leaky tube. More generally, our research lab studies a variety of topics related to wetting and adhesion of soft materials. Many of the same ideas that we use to understand how a leak can stop itself are also relevant to understanding how sticky stuff sticks and stays stuck — and I’ll tell you about that too!

Join us on Friday, Mar. 25, from 12 - 1 p.m. to hear the presentation. A takeaway lunch will be available in Hayes 201 before the meeting at 11:50. We hope to see you then!

 

Dan Homan, professor of physics and astronomy at Denison University, will present a talk on active galaxies, relativistic jets, and supermassive black holes. 

Quasars, and their extreme variety "Blazars," are the brightest examples of Active Galactic Nuclei (AGN) which are powered by supermassive black holes voraciously feeding on material flowing into the center of their galaxy. Some of these AGN also have collimated outflows of highly energetic plasma which appear to stream away from the center of the galaxy at many times the speed of light. In their most spectacular form, these relativistic jets can extend for hundreds of thousands of light-years, well outside the host galaxy, to inflate giant radio lobes.  I study these jets very near their origin at the center of the galaxy to understand their structure and how they are accelerated and collimated. This work involves untangling the effects of relativistic motion near our line of sight to reveal the underlying properties of the jet itself.

Join us on Friday, Feb. 25, from 12 - 1 p.m. to hear the presentation. A takeaway lunch will be available in Hayes 201 after the meeting. We hope to see you then!

Dr. Rachel Bezanson of the University of Pittsburgh will lead a talk on the formation and evolution of massive galaxies throughout cosmic time.

Galaxies are extraordinarily complex collections of stars, gas, and dark matter. The largest galaxies, though relatively rare in number, host most of the stars in the Universe and deep in their cores harbor the most extreme supermassive black holes. Today massive galaxies are red and dead ellipticals with little ongoing star formation or organized rotation; naturally they were expected to be relics of a much earlier formation epoch. In this talk I will briefly review the paradigm that has emerged over the last decade, discussing the structural and kinematic evolution of massive galaxies during and after they stopped forming stars (“quenched”) and eventually transformed from rotationally supported disks into kinematically hot ellipticals. Spectroscopic studies of distant galaxies reveal the chemical compositions, detailed star formation histories, and internal motions of stars and gas and are necessary to answer open questions about the details of that cosmic formation and shutdown. I will describe my team’s observational efforts to characterize the histories of galaxies like our Milky Way and larger at three critical moments in the 14 billion year history of the Universe, each corresponding to a large spectroscopic program.  This work includes studying galaxy metamorphosis at ~half the age of the Universe, highlighting results from the ultra-deep LEGA-C spectroscopic survey of ~3500 massive galaxies and the focused multi-wavelength SQUIGGLE survey of post-starburst galaxies caught immediately following their cosmic shutdown. I will discuss my plans to extend spectroscopic studies of galaxies to the earliest moments in cosmic history, with the UNCOVER treasury program on the upcoming NASA flagship observatory - JWST. Finally, my team will connect-the-dots through the peak of cosmic star formation (~10 billion years ago) using the next-generation massively multiplexed Prime Focus Spectrograph on the Subaru Telescope.

Lunch will be available in the Hayes 201 before the talk. If you cannot join us in person, join us via Zoom. We hope to see you there!

David Summers '12 of the Boston Consulting Group will present his Ph.D research conducted at the University of Maryland regarding the Casimir Lifshitz effect. You can join us for this presentation from 12 to 1 p.m. in Hayes Hall 211/213. 

The Casimir-Lifshitz effect predicts an electromagnetic force even between uncharged materials caused by the coupling of random charge fluctuations. I will give a brief overview of the field of study, focusing on the first experiment that measured the Casimir-Liftshitz torque. The torque was first theorized decades ago, but the small magnitude of the effect made it difficult to verify. Our experimental design used liquid crystals as a probe, allowing optical measurement over nanometer-scale separations. As a Kenyon physics alum, I will also briefly share my experiences in graduate school, government and the private sector.

Lunch will be provided in the Hayes Hall lobby after the talk. If you cannot attend in person, feel free to join us via Zoom.

The Physics Department will host a talk on resources to boost your career in physics led by Crystal Bailey, head of the Career Program at the American Physics Society. 

Physics degree holders are among the most employable in the world, often doing everything from managing a research lab at a multi-million dollar corporation, to developing solutions to global problems in their own small startups. Science and Technology employers know that with a physics training, a potential hire has acquired a broad problem-solving skill set that translates to almost any environment, as well as an ability to be self-guided and -motivated so that they can teach themselves whatever is needed to be successful at achieving their goals. Therefore it's no surprise that the majority of physics graduates find employment in private — sector, industrial settings. At the same time, only about 25% of graduating PhDs will take a permanent faculty position — yet academic careers are usually the only track to which students are exposed while earning their degrees.

In this talk, I will explore less-familiar (but more common!) career paths for physics graduates, and will provide information on resources to boost your career planning and job hunting skills.

You can join us on Friday, Feb. 4, from 12 - 1 -.m. to hear the presentation. A takeaway lunch will be provided after the colloquium. If you cannot attend in person, feel free to join us via Zoom.

Fall 2021 Physics Colloquiums

In the fall semester, several students majoring in physics pursued Independent research projects with a faculty advisor. The research topics spanned a wide range. These students will present their work at a poster session during the regular departmental colloquium hour. Come support your fellow physics students!

Posters will be available for viewing in Hayes 211/213 and Hayes 215 from 12 to 1 p.m. on Friday, Dec. 10. A takeaway lunch will be available in Hayes 201 for guests.

Professor of Physics David Weiss of the Pennsylvania State University will be presenting on the role of atoms in quantum computing. You can join us for this presentation from 12 to 1 p.m. in Hayes Hall 211/213.

I will first explain how we use lattices made from light to trap 3D arrays of single neutral atoms. Then I will show how these atoms can be used as the quantum bits (qubits) in a quantum computer. Among the tools we have developed to this end, I will focus on how we sort 50 atoms in the 3D lattice, in a real world demonstration of a Maxwell's demon, arguably the first such demonstration with more than a couple of particles.

In this exciting combination of biology and physics, assistant professor of Physics and Astronomy, Srividya Iyer-Biswas, of Purdue University will explain her research in defining quantitative laws for understanding cell division and biological systems.

There has been a longstanding quest for uncovering the quantitative laws governing the stochastic growth and division of individual cells. While great strides have been made in unravelling and modeling the details of the gene regulatory networks which dictate growth and division for different organisms, there is a regrettable paucity of quantitative physical laws derived from the complementary “top down” perspective. Introducing the unique combination of technologies that facilitated probing stochastic cellular dynamics with unprecedented precision, I will first summarize the "scaling laws" that govern fluctuations in growth and division of individual cells under steady-state growth conditions. Taking a minimalist perspective, I will argue for how these scaling laws reveal an elegant physical principle governing these complex biological processes: a single cellular unit of time, which scales with external conditions, governs all aspects of stochastic cell growth and division at a given condition. I will then focus on applications of the technology to probe more complex growth conditions, the corresponding generalizations of the physical principle, and the implications for the underlying biological systems design. Finally, I propose an integrative perspective of microbial growth dynamics under balanced conditions, by introducing a multi-scale theoretical framework that takes observables at both scales, single-cell and population, into account. Time permitting, I will make connections with stochastic intergenerational homeostasis of bacterial growth and form.

Join us in Hayes 211/213 from 12:10 to 1 p.m. to hear the presentation. Food will be served after the meeting.

Professor of Physics Nicole Zellner of Albion College will be presenting on astrobiology and the search of life in space. You can join us for this presentation from 12 to 1 p.m. in Hayes Hall 211/213. If you cannot join us in person, feel free to join us virtually by following this Zoom link.

Astrobiology is defined as the study of life in the universe. But, then, how can you define life itself? There are three main requirements of life known to us: energy, water and organic molecules. Formed in molecular clouds, on dust grains, are the building blocks of life: biomolecules. Energy changes simple molecules into more complicated ones and these are used in DNA. The identification of these prerequisites of life has opened a greater question: is there life in space? Specifically, we talk about the detection of water, energy and organic molecules from space debris on Mars, thus leading to the conclusion that with all the right elements present maybe it is a matter of time till a discovery of life.

Similarly, on Europa, Titan and Enceladus, there is a distinct possibility of the presence of life. However, it may not be the kind of life you imagine. To find life as we know it, we look towards the stars at the Galactic Habitable Zone, Stellar Habitable Zones and Extrasolar Planets. The likelihood of finding intelligent life is explored by the Drake equation, Seager equation and practically, using SETI for the observation of radio signals. This talk will carry you on a cosmic journey to uncover the meaning of life in astrobiological terms, a new kind of life and perhaps, a familiar one in an unfamiliar place. 

Professor of Physics Susan Lehman of the College of Wooster will be presenting on experiments in the study of critical systems. You can join us for this presentation from 12 to 1 p.m. in Hayes Hall 211/213. If you cannot join us in person, feel free to join us virtually by following this Zoom link.

A granular system behaves in some ways like a liquid with an ability to flow, and in some ways like a solid with a stable fixed structure if undisturbed. A tiny stimulus to the pile most often results in only a small response, but the same small stimulus can also create an unpredictable and catastrophic collapse of the pile. These collapses occur both in natural settings, with hazards such as landslides and snow avalanches, and in industrial situations, where granular materials like sand or agricultural grains need to flow freely. We use a simple experimental system — a 3D conical pile of uniform beads — in order to model these real-world physical systems. We investigate the dynamic response of the pile by recording avalanches from the pile over the course of tens of thousands of bead drops. The resulting behavior is well-characterized by universal power laws and scaling functions, relating this work to the broader study of critical systems.

For Family Weekend, Professor Benjamin Schumacher will discuss various impossibilities in physics and what they mean regarding our understanding of the world. Join us in Hayes Hall 211/213 at 12 p.m. for this exciting presentation on the impossible. If you cannot join us in person, feel free to join us virtually by following this Zoom link.

Some things are possible and some are not. That line between the possible and the impossible can tell us a lot about the way nature works. In this talk we will ponder a few impossibilities, from the famous (time travel) to the obscure (quantum cloning), using them to discover some of the physical principles that govern information in our quantum universe. As one might expect upon a journey into wonderland, our constant companion will be Alice — thanks to her creator Lewis Carroll and her most famous illustrator Sir John Tenniel. Many surprises will await us through the looking-glass of the impossible.

Michael Lisa will be offering a look at the unique applications of physics in the world of sports, encompassed in a semester course at Ohio State University. Join us in Hayes Hall 211/213 at 12 p.m. to learn more. 

Ohio State University offers a one-semester course on the physics of sports, which satisfies a GEC science requirement of all students. Scholarship athletes, business and liberal arts majors make up the majority of the ~80 students enrolled in the class, though interested sports enthusiasts from more technical fields join as well. The class is far from the "Physics for Poets" type of course that some expected, leading to some initial math- and science-anxiety. It is gratifying when some of this anxiety is replaced by a self-confidence in many students that they can, indeed, handle and appreciate a "real" mathematical science course on material they already enjoy. While the underlying physics lies of course squarely  in the realm of classical mechanics, and familiar topics must be covered, the course aims to be unique, not simply a standard classical mechanics class with sports examples. I will discuss the several challenges to develop a course like this and share some specific lessons learned and insights gained over many years. This talk does not present formal physics education research.

Professor of Physics Smitha Vishveshwara from the University of Illinois Urbana-Champaign will be presenting on "Quantum Voyages, Cosmic Journeys: Exploring Physics through the Arts." This presentation takes a unique gaze at physics through the artistic spectrum. Join us in Hayes 211/213 at 12 p.m. for the presentation. 

From ancient monuments to modern day films, the confluence of the arts and physics has resulted in  creations that have led to a deeper understanding of nature, to friendly and enchanting ways of perceiving science in action, to giving the arts a new dimension,  to technological progress, and to pure fun! In this talk, I will describe the educational power of such confluences and recount some of our experiences in this realm.  In a project-based interdisciplinary course entitled Where the Arts meets Physics, we bring alive the universe and the quantum world through installation and performance — cosmic canopies housing black hole mergers, raps on radioactivity, Warhol versions of Bohr-Einstein debates, and more. Collaborations with theater, music and dance have led two original performance pieces that explore the magic and beauty of the quantum world, Quantum Voyages and Quantum Rhapsodies. I will share the science, stories, and process behind the making and performing of these pieces, and conclude with a description our latest adventure — a virtual art-science festival entitled the Illuminated Universe.  

Our fourth and final honor student speaker will be Mary Gerhardinger. She will be presenting on "Modeling Relativistic Fluids in General Relativity." Join us in Hayes 211/213 at 1 p.m. for the presentation. Food will be provided before the presentation at 12:30 p.m.

Current models of cosmology predict the formation of black holes near the beginning of the Universe’s life that are not a result of stellar collapse. These black holes, called Primordial Black Holes (PBH), could help explain our currently incomplete understanding of the origin of super massive black holes and the composition of dark matter. Exactly how these PBH are formed, however, has not been studied rigorously. In this talk I will introduce my honors work examining the possible formation of PBH from primordial density fluctuations modeled through the interaction of radiation with gravity. Specifically, I will discuss the best approximations we can use to describe both radiation (as a relativistic fluid) and gravity (as Einstein’s theory of General Relativity). We will investigate both the theories of fluids and general relativity before discussing how to implement this model onto computational simulations, performed using a tool called GABERel.

The third of our honors student presentations will be Tom Yoda discussing trapped ultra-cold atoms. Join us at noon on Friday, Sept. 17.

"The Rydberg excitation blockade, or the suppression of excitation due to strong interactions, is a critical component  of quantum computation and simulation using neutral atoms. However, unwanted state-mixing effects near Förster resonance cause the blockade to break down. My research group performs state selective field ionization spectroscopy on a  shot-by-shot basis to observe this effect. I will introduce you to the world of trapped ultra-cold atoms. Then, I will propose my honors project of controlling unwanted state-mixing effects using different parameters, not just the principal quantum number or density of the atoms, but also pulse duration and Rabi frequency. This control will be critical in future implementations of neutral-atom quantum information."

In the second of our honors presentation series, Erika Florio '22 will be exploring the physics of black hole-scalar field interactions. This event will be virtual. Join us via Zoom.

As it stands, our best description of gravity, general relativity, is not fully consistent with our most successful physical theory ever, quantum mechanics. Examining high-energy phenomena, such as the physics of the early universe and regions of extreme spacetime curvature, is essential for determining where our theory of gravity may fail, and how we can move beyond it. This presentation will introduce Ericka's honors work examining the physics of black hole-scalar field interactions. She will perform this computation using GABERel, a numerical tool that can couple full (numerical) general relativity with scalar fields without making any assumptions, in a fully non-linear context. She will generate scalar field wave packets and a black hole, then allow the wave packet to hit a black hole. She will then examine the products of this interaction in configuration space as the frequency of the wave packet changes in order to determine which types of interactions are possible and on what scales.

This September, the Physics Department is hosting a series of presentations by our very own honor students. For Friday, Sept. 3, we welcome Quinn Curren (class of 2022) for his presentation on pulsar candidates. Due to recent changes on campus, this presentation will be a virtual event.

Pulsars are rapidly spinning neutron stars that emit electromagnetic radiation along their magnetic poles. The fastest pulsars, known as millisecond pulsars, rotate hundreds or thousands of times each second and have periods as precise as atomic clocks. Scientists can observe gravitational waves through the careful timing of a large collection of millisecond pulsars, since gravitational waves will shift the correlated arrival time of these pulses as measured on Earth. These Pulsar Timing Arrays become more sensitive as more pulsars are discovered. Pulsars are observed mainly using radio telescopes, but radio emissions from other sources are also picked up by these telescopes. Advanced software is used to find pulsar candidates from radio telescope observations across the sky. Radio Frequency Interference (RFI) and noise comprises well over 99 percent of the candidates in the PALFA survey, and can closely resemble genuine pulsar candidates. However, manually sorting through the pulsar/RFI candidates is time consuming and inefficient. One method of analyzing the candidate list is to create an algorithm that will automatically rank the candidates using machine learning algorithms (MLA). This project aims to create a novel MLA that will rank pulsars accurately and separate them from non-pulsar candidates. Machine learning aims to recreate the way that humans learn; and like MLAs, this project’s structure is based upon the methods that experts use to manually rank candidates.

Enjoy a welcome meeting to the Physics Colloquium series. Meet other students and members of the department and discuss what's happening this year in physics. Lunch will be served from 12 to 1 p.m.