Physics Colloquium Archive

As the new semester begins, it's time to have some fun with physics! Join us once again as we get together for the first Friday of the new semester to meet and share what's going on in physics!

Catch up with old friends and meet new ones as we say hello to all our fellow physics faculty and students. We will also share information about what is happening in the department. Join us to learn about research opportunities, upcoming events and our colloquium series.

Pizza and drinks will be available in Hayes 216 (the Physics Lounge) on Friday, Jan. 19, from 11:45 a.m. to 12:15 p.m. Grab a slice and head to Hayes 211/213 for the presentation. We hope to see you there!

At Earth we observe a flux of protons and nuclei called "cosmic rays." Their energy has been measured at up to 100 million times higher than the energy of particles accelerated at the Large Hadron Collider at CERN. What is accelerating particles and nuclei to these extreme energies?

For decades the answer has eluded us. Tracing cosmic rays to their point of origin is difficult as they are deflected by magnetic fields. Highly energetic ghost particles (neutrinos) are created in the same places as cosmic rays, but are neutral particles. Neutrino astronomy is a direct way to solve the question of the origin of cosmic rays. Neutrinos can be detected in the IceCube detector at the South Pole. Though difficult, the data can be used to reconstruct a point of origin. Even though only a few astrophysical neutrinos have been detected there is evidence for a connection with black holes.

Accreting supermassive black holes, especially those with outflows that reach relativistic speeds are promising particle accelerators that could explain high-energy cosmic rays and neutrinos. I will discuss supermassive black holes and their role in producing cosmic rays and "ghost particles."

Join us on Friday, Jan. 26, for this exciting presentation from Dr. Fe McBride, assistant professor of physics at Bowdoin College. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

The behavior of clouds is a crucial unknown in climate modeling. This is because many different concepts of physics play a crucial role in cloud formation, including fluid transport, thermal physics, droplet formation, and radiation. In recent years, we have come to appreciate the role of organization of clouds: specific patterns of clouds form for a reason, and those patterns in themselves impact the properties of the clouds, such as reflection of sunlight or rain formation. My work focuses on large computational studies of interactions between clouds and their environment. In this talk, I will discuss what makes cloud behavior so non-linear, how they are currently represented in the climate models, and some ideas on how to improve representation of cloud organization in those climate models.

Join us on Friday, Feb. 2, for this exciting presentation from Thijs Heus, associate professor of physics at Cleveland State University. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

Magnetic random access memory (MRAM) would combine the benefits of the hard drive (non-volatile, cheap, high density of bits) with the benefits of RAM (fast, mechanically robust). One proposal for MRAM involves the vortex state of nanorings, a state in which the magnetic moments align circumferentially in the clockwise or counterclockwise direction. For a symmetric ring in a uniform field, these states are energetically degenerate and cannot be selected experimentally. A circular field allows us to study the switching behavior between these vortex states. We have developed an experimental technique to apply a local circular field by passing current through the tip of an atomic force microscope. I will discuss how the atomic force microscope works, our experimental results demonstrating switching between the vortex states, and our understanding of the evolution of these states based on our simulations. We predict novel states that arise from both energy minimization and topological constraints.

Join us on Friday, Feb. 9, for this exciting presentation from Katherine Aidala, professor of physics at Mount Holyoke College. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

Spacetime symmetries play a crucial role in understanding our nature. Especially, invariances under Lorentz and CPT transformations are foundations of General Relativity (GR) and the Standard Model of particle physics (SM), the two current best theories describing nature. However, tiny violations of these symmetries could appear in a more fundamental theory unifying gravity with quantum physics. Motivated by this, numerous high-precision experiments spanning various subfields of physics have been performed to search for possible Lorentz- and CPT-violating signals. In this talk, I will focus on the prospects of testing Lorentz and CPT symmetries using confined particles and antiparticles in Penning-trap experiments. The theory of Lorentz- and CPT-violating quantum electrodynamics will be outlined. Leading-order effects to charge-to-mass ratio and magnetic moment measurements and their comparisons between particles and antiparticles will be derived. In particular, experimental signals involving sidereal and annual variations due to Lorentz and CPT violation will be discussed. Using existing results from Penning-trap experiments, new constraints on coefficients for Lorentz violation will be presented.

Join us on Friday, Feb. 16, for this exciting presentation from Yunhua Ding, assistant professor of physics and astronomy at Ohio Wesleyan University. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

When we think of a galaxy, we often imagine a spinning disk of stars and gas surrounding a glowing center. But galaxies are more than meets the eye, and the disks we see are just a small part of the whole. We now know galaxies to be surrounded by huge halos of gas that provide the material from which stars are formed. In this lecture, we will explore the scope of these nearly invisible halos, describe how we can detect them, and look at computer simulations that help reveal their lesser-known properties and their influences, such as magnetic fields!

Join us on Friday, Feb. 23, for this exciting presentation from Ed Buie, assistant professor of astronomy at Vassar College. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

The direct detection of gravitational waves in 2015 opened up a new window in astronomy and astrophysics and provided new opportunities to study fundamental physics that is not accessible in the lab. Chad Hanna, professor of physics, astronomy and astrophysics at Penn State University, will describe what we have learned about our universe through observing merging black holes and neutron stars with LIGO and Virgo.  He will also discuss ongoing observations and the prospects for new discoveries going forward.

Join us on Friday, Mar. 22, for this exciting presentation from Hanna. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

Who plans all the physics trips? Who are the people that organize physics merch? Who gives out candy on or after Valentine’s day? To get these answers and more please join us on March 29 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 or guardians across all departments on campus. We will give a brief presentation welcoming our visitors, introducing your officers, and distributing some physics-themed stickers. Afterwards, please join us in enjoying some phantastic physics alongside the children of the college. From catapulting objects at high velocities, to making ice cream with dry ice, 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!”

Pizza and drinks will be in Hayes 216 from 11:45 a.m. to 12:15 p.m. on Friday, March 29. Activities will begin at 12:10 p.m. in Hayes 211/213. We hope to see you there!

Within the computer that you are using to view this abstract lies a microchip, roughly the size of a fingernail, yet it houses billions of transistors. The process of creating such a device, with its billions of nanometer-sized structures, stands as a pinnacle of technological advancement, representing the culmination of decades of innovation in physics, chemistry, and engineering. In this talk, I will begin by detailing the steps required to fabricate a much simpler device that is commonly used in physics experiments. This example will serve as an introduction to the complex world of chip manufacturing, highlighting key techniques such as photolithography, etching and thin film deposition. These foundational methods are the essential building blocks of semiconductor fabrication, enabling the precise manipulation of materials at the nanoscale.

Join us on Friday, Apr. 5, for this exciting presentation from Aidan Lee, failure analysis development engineer at Intel Corporation. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

Postponing work impacts virtually everyone at some point, especially among students. In this talk, we will discuss how academic procrastination can be easily observed by looking at when students complete online assignments. We will examine how students can be characterized and differentiated by their completion of online assignments throughout the semester and discuss how instructors can incentivize developing good study habits in their classroom. Additionally, we will discuss a learning tool developed to improve student’s basic math skills that are needed in a physics class. This tool has been shown to improve accuracy and reduce the time it takes for students to solve basic math problems needed in physics. Finally, we will discuss what skills sets and career paths are available to physics education researchers.

Join us on Friday, Apr. 12, for this exciting presentation from Megan Nieberding, visiting professor of physics at The College of Wooster. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

Over the last few decades, scientists have found thousands of planets beyond our own. Some of those planets might be habitable, and perhaps even inhabited already; but how can we tell? Clara Sousa-Silva looks for signs of life on other planets using astronomical tools to detect faint signals emitted by potential alien biospheres. In this presentation, Clara draws on her experience investigating strange molecules on strange planets, and her efforts to answer the question: "Would we know life if we saw it?"

The work presented in this talk combines organic chemistry and quantum mechanics as tools for the interpretation of astrophysical signals and, ultimately, the detection of life on an exoplanet. Whether alien life will produce familiar gases (e.g., oxygen) or exotic biosignatures (e.g., phosphine), painting a confident picture of a potential biosphere will require a holistic interpretation of an atmosphere and its molecules. In this talk Sousa-Silva will describe ongoing efforts to train the next generation of scientists to decipher exoplanet atmospheres, and ultimately to detect a biosphere through the identification of atmospheric molecules, in particular those that might be produced by non-Earth-like life.

Sousa-Silva is a quantum astrochemist and molecular astrophysicist. She investigates how molecules interact with light so that they can be detected on faraway worlds. Sousa-Silva spends most of her time studying molecules that life can produce so that, one day, she can detect an alien biosphere. Her favorite molecular biosignature is phosphine: a terrifying gas associated with mostly unpleasant life. When she is not deciphering exoplanet atmospheres, Sousa-Silva works hard to persuade the next generation of scientists to become an active part of the astronomical community.

Join us on Friday, Apr. 19, for this exciting presentation from Clara Sousa-Silva, assistant professor of physics at Bard College. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

How did printing and publishing make scientific discovery possible in the early stages of the Scientific Revolution? We'll look at the mathematical, astronomical, and natural philosophical books collected in the 19th C. by J. N. Lewis of Mount Vernon and now in Kenyon Special Collections, including works by Nicolas Copernicus, Tycho Brahe, Johannes Kepler, Francis Bacon, Johannes Hevelius, Isaac Newton and others, to see the way that new ideas were developed and transmitted.

Join us on Friday, April 26 for this exciting presentation and tour of Kenyon's Special Collections with Dr. Piers Brown, associate professor of English. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:10 p.m. and we will begin walking to Chalmers at 12:10 p.m. We hope to see you there!

A new year, a new chance to get involved in the Physics Department. Join us once again as we get together for the first Friday of the new school year to meet and share what's going on in physics!

Catch up with old friends and meet new ones as we say hello to all our fellow physics faculty and students. We will also share information about what is happening in the department. Join us to learn about student work opportunities, research opportunities, joining the Society of Physics Students and our colloquia series.

Pizza and drinks will be available in Hayes 216 (the Physics Lounge) on Friday, August 25, from 11:45 a.m. to 12:15 p.m. Grab a slice and head to Hayes 211/213 for the presentation. We hope to see you there!

Please join us on Friday, Sept. 1, to find out about summer-research activities in physics and how you can plan ahead to participate in such activities. Several students who pursued research projects during the past summer, both at Hayes and at other institutions, will share their experiences. After their presentations, you will get a chance to speak with these students regarding their experiences, and in particular, to find out how they got started pursuing research.

Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. The presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

The origin of certain objects in the universe, such as supermassive black holes, are still not clear to us. Black holes that dynamically form in the very early universe, called primordial black holes, could help explain the origin of supermassive black holes and even the composition of dark matter. In this talk, I will introduce my honors work examining the possible formation of PBH during preheating. I will also be investigating the possibility of scattering gravitational waves off of black holes. I will be using GABERel for both of these projects, which implements fully nonlinear numerical general relativity.

Join us on Friday, Sept. 8, for the first of this year's honors talks presented by physics students pursuing honors. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. Come and support your fellow physics classmates. We hope to see you there!

Michael Crescimanno, professor of physics, astronomy, geology and environmental sciences at Youngstown State University will share his work on electromagnetically induced transparency.

Enantomeric ripening in chemistry, the matter-antimatter asymmetry in the early universe, comparing the effects of driving your car forward or backing up your car over a speedbump and how scallops swim in viscous media are all deeply related manifestations of the same underlying physical principle crystalized most succinctly in the Sakharov Conditions, which pertain to systems with a broken discrete symmetry that are driven out of equilibrium. After exploring a few illustrative examples of the Sakharov Conditions in action, we test it's applicability in a quantum mechanical regime via a recent experiment using Zeeman Electromagnetically Induced Transparency (EIT) in a 87Rb vapor cell. This will allow us a first glimpse of the effect "coherences" have on the Sakharov Conditions paradigm.

Join us on Friday, Sept. 15, for this exciting presentation from Crescimanno. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

Neutral Rydberg atoms, or atoms in highly excited states, have many properties that are useful when studying quantum information or building quantum devices. Our lab has recently studied entangled states of three Rydberg atoms, which might find applications to qutrits or three-quibit gates. The strong coherence of these entangled states is the key to their usefulness. Lucy Shamel will be investigating the properties of these states, specifically their coherence time, to see how we might control and prolong it. 

Join us on Thursday, Sept. 21, for our second honors talk this semester presented by physics students pursuing honors. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. Come and support your fellow physics classmates. We hope to see you there!

Neutron-stars deform due to tidal forces as they coalesce, and this tidal deformability is modeled by a single parameter, to first order. The tidal deformability and NSs are able to be measured by advanced ground-based interferometers designed for observing gravitational waves (GWs) and can carry information about the neutron-star equation of state (EoS). Bilby is a popular software among researchers interested in performing Bayesian parameter estimation on GW data. To estimate the EoS from a binary neutron star merger, we create generic EoS models from which to sample. Then, we use Bilby to recover posterior distributions on the models’ parameters. To translate internal state properties (e.g. pressure, density, enthalpy) to macroscopic stellar properties (e.g. radius, love number, tidal deformability) we need to solve a series of differential equations known as the TOV equations. The current TOV solver employed by Bilby fails to solve these equations as parameters stray from conservative EoS values. The goal of my research this year, under Professor Leslie Wade, is to implement a more robust TOV solver (RePrimAnd) into Bilby, expand the EoS parameter space, make and investigate a phase-transition equation of state, and do EoS parameter estimation runs with these new implementations on real LIGO data (GW170817).

Join us on Friday, Sept. 22, for this final honors presentation of the semester presented by physics students pursuing honors. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. Come and support your fellow physics classmates. We hope to see you there!

Frank N. von Hippel, a theoretical particle physicist by training, a senior research physicist and a professor of public and international affairs emeritus at Princeton University, will be giving a virtual presentation here at Kenyon on the history of the debate among physicists regarding nuclear weapons after the release of Christopher Nolan's "Oppenheimer."

The film barely hints at the debate among the Manhattan Project physicists on “the impact of the Gadget on Civilization” and their efforts to influence the decision on using nuclear weapons against Japan. It also does not explain that Oppenheimer’s “trial” and termination as a government advisor was due to his opposition to developing the H bomb because it would carry “much further than the atomic bomb itself the policy of exterminating civilian populations.” During the Cold War, physicists worked for policies to reduce the danger. Despite near misses, no additional cities have shared the fates of Hiroshima and Nagasaki. Now, with President Putin making nuclear threats against NATO, and China and the US in a growing confrontation over Taiwan, physicists are mobilizing against a new nuclear arms race and to advocate policies such as no first nuclear use.

Hippel co-founded Princeton’s Program on Science and Global Security, the International Panel on Fissile Materials, and the Physicist’s Coalition for Nuclear Threat Reduction. During the 1980s, he worked with Soviet physicists advising Mikhail Gorbachev on initiatives to end the nuclear arms race and the Cold War. During 1993-4, he worked in the White House Office of Science and Technology on nuclear policy issues including improving the security of Russia’s fissile materials, partnering with Russia on a global effort to convert research reactors from weapon-grade to low-enriched uranium fuel, and disposing of the plutonium from excess Cold War warheads.

Join us on Friday, Sept. 29, for this exciting presentation from Hippel. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

Our own Professor Frank Peiris will be discussing semiconductors and the research he conducted in Berlin during his sabbatical last year.

Silicon-based semiconductors have fulfilled the promise of producing mature technologies such as electronics, communications, and storage. They are less effective, however, for high-power applications, such as electric vehicles and renewable energy production. In this talk, I will focus on two alternate semiconductors which I researched during my sabbatical last year at the Paul Drude Institute in Berlin. First, I will show how scandium nitride, a wide-band gap semiconductor, was grown using molecular beam epitaxy, and how its structural, optical and electrical properties were measured. Second, I will focus on a class of semiconductors called transition metal dichalcogenides and elaborate on how these materials challenge our current understanding of the behavior of electrons in materials.

Join us on Friday, Oct. 13, for this exciting presentation from Peiris. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

Walter Kemp Professor in the Natural Sciences and Professor of Physics Amy Graves will be visiting campus from Swarthmore College to discuss gender in physics and where that conversation is heading today.

Physics, in the form that we do it today, has long been the domain of cis males (and in western countries, cis white males). Happily, this is changing. But the past casts a long shadow, and we live in a real world where race and gender identity strongly define us. This makes change slow and circuitous.   

Questions and comments are welcome during this talk. You are warmly encouraged to draw on your own lived experiences in school and college and/or hope for a STEM career. The talk which will be structured around some useful themes:

Myths – Commonly held beliefs about what it means to be a successful physics student or professional … not always grounded in the truth.

Memes – The words and images in popular culture that spread themselves around the world …  signifying what physics is and what we should be.

Marginality – The exciting (lol) situation of existing on the margins of academic or workplace culture …  What are some of the coping strategies we can adopt, and resources that we can access to be resilient ourselves, and a good advocate for others?

This week's colloquium is co-sponsored by the Program in Computing. Join us on Friday, Oct. 20, for this exciting presentation from Graves. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

We’re calling all ghouls, goblins, warlocks and witches to attend the Society of Physics Students (SPS) Happy Halloween Colloquium. We swear that there will be no hocus pocus in our presentation as it will be kept short. This leaves the rest of the time to be filled with your cackles, roars and out-of-this-world conversation. If that isn’t enough there will be pumpkins to paint and candy to eat. So, grab your pointy hats, magical staffs and burbling cauldrons, and come to Hayes 211/213 this Friday for a Mumummemberable lunch.

Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the doors will open for the party at 12:10 p.m. in Hayes 211/213. We hope to see you there!

Dripta Bhattacharjee, Kenyon's post doctoral researcher in physics, will present on gravitational wave detectors, how they are calibrated and how physicists continue to improve that process of calibration to increase accuracy.

The Laser Interferometer Gravitational-wave (GW) Observatories (LIGO) in the USA started their fourth observing run (O4) in May 2023. The detector in Italy, Virgo, and the one in Japan, KAGRA, are slated to join LIGO in the observation run soon. Nearly 100 GW events have been detected by the network of GW detectors since the first detection in 2015. Improved detector sensitivities for O4 suggest significantly higher event rates. As signal-to-noise ratios increase, reduction of calibration uncertainties becomes increasingly important for optimally extracting the astrophysical information encoded in the GW signals. The observatories employ systems known as photon calibrators (Pcal) to generate displacement fiducials at the 1x10-17 m level via radiation pressure. These systems rely on calibrated laser power sensors to enable accurate and precise displacement calibration. This technique has been developed in LIGO for more than a decade. To provide absolute calibration accuracy at a sub-percent level for the latest O4 run, the global network of GW observatories along with NIST and PTB, national metrology institutes in the US and Germany, have implemented a novel calibration scheme. Additionally, the new scheme should increase our confidence in our calibration accuracy and reduce relative calibration errors between observatories in the GW network. Providing absolute calibration of the GW data with uncertainty below 1% is imperative to achieving interferometer calibration at a percent accuracy level. This is necessary for enabling interesting science, for example resolving the SHoES-Planck tension in Hubble parameter estimation.

Join us on Friday, Nov. 3, for this exciting presentation from Bhattacharjee. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

Randolph Peterson, the Tom Costen Professor of Physics and chair of the Physics and Astronomy Department at Sewanee: The University of the South, will be visiting campus to introduce students to new and exciting experiments using graphene.

Graphene, one-atom-thick graphite, was discovered and identified in 2004 by Andre Geim and Konstantin Novoselov. For this work, they were awarded the 2010 Nobel Prize in Physics. Over 30,000 journal articles on graphene have been published since its discovery. We have the opportunity to introduce our students to some of the basic physical properties of graphene in our advanced lab courses while it is still an exciting material, both scientifically and commercially. I will give an overview of some of the experiments that can be introduced into the undergraduate curriculum and the results that you can expect.

Join us on Friday, Nov. 10, for this exciting presentation from Peterson. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

Michael Poirier, professor and chair of physics at the Ohio State University will be joining us on campus to discuss transcription factors and how they can be used to access sites wrapped into nucleosomes.

The physical organization of all eukaryotic genomes is evolutionarily conserved and functions to regulate gene expression. The molecular basis of this organization involves histone protein octamers repeatedly wrapping genomic DNA into nucleosomes forming long chromatin fibers. This organization controls accessibility of transcription factors (TFs) to their DNA regulator sites to activate transcription by “opening up” or “unlocking” chromatin. I will discuss mechanisms transcription factors use to gain access to sites tightly wrapped into nucleosomes. We will find that the interplay between the dynamics of transcription factor binding/dissociation and nucleosome/chromatin DNA compaction is key to understanding TF function. This framework helps in understanding how chromatin regulation of TFs and co-activators prevents certain TFs being “blocked” from their target sites while other TFs efficiently target their sites leading to gene activation.

Join us on Friday, Dec. 1, for this exciting presentation from Poirier. Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. and the presentation will begin in Hayes 211/213 at 12:10 p.m. We hope to see you there!

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!

Join us on Friday, December 8, from 12:10 to 1 p.m. in Hayes Hall 211/213 to check out all the research projects your fellow majors did this semester. Lunch will be available in Hayes 216 from 11:45 to 12:15. We hope to see you there!