Physics Colloquium

A new year, a new chance to get involved in the Physics Department. Join us as we gather 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 Hall 215 on Friday, August 30, 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!

Two-dimensional transition metal dichalcogenide (2D-TMD) systems are a rich field of research within condensed matter physics. The large variety of physical characteristics exhibited by this class of material have led to wide interests, mainly due to its potential applications in optics and information systems. In this presentation I propose to conduct spectroscopic ellipsometry studies on several 2D-TMD systems, determining their thickness-dependent dielectric functions. Concurrently, I propose to conduct computational studies on these 2D-TMD systems using Density Functional Theory (DFT). DFT is a computational approach to determine the band structure and the dielectric functions of condensed matter systems. Implementing the DFT tool in our lab will enable us to perform theoretical/computational studies on materials we investigate, enabling us to corroborate the experimental results with first principles calculations. 

Join us on Friday, Sept. 6, 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!

"Thirty years ago, I was a physics graduate student. I left without finishing my doctorate and switched careers. Instead of trying to do science, I now write about science at the New York Times. Science and equations are precise. Words are not. Writing about science is a series of tradeoffs, explaining the big picture for non-scientific readers while fuzzing the details. How well do I do? How well would you do?"

We're excited to invite you to join us on Friday, Sept. 13, to gain insights on writing, science and communicating scientific concepts from Kenneth Chang, science reporter at the New York Times. Enjoy a complimentary lunch in Hayes 216 from 11:45 a.m. to 12:15 p.m., followed by an engaging presentation in Hayes 211/213 at 12:10 p.m. Don't miss out on this opportunity! See you there!

Nobel Laureate in chemistry and professor of biochemistry and molecular biophysics and biological sciences at Columbia University Irving Medical Center, Joachim Frank will visit Kenyon for several presentations on Sept. 17. The first of these presentations will be on time-resolved cryo-EM and its impact on structural biology.

The standard protocol of cryo-EM does not allow visualization of reactions since the time for sample deposition on the grid and blotting is in the range of several seconds. To study the process of a reaction, as it goes through one or more short-lived intermediates, we have developed a method of time-resolved cryo-EM. Here two reactants are mixed in a microfluidic channel, allowed to react for a defined time (between 10 and 1000 milliseconds), and the reaction product sprayed onto the EM grid as the latter is being plunged into the cryogen. Novel PDMS-based microfluidic chips prove to give exceptional reproducible results.  

With this approach we have been able to visualize short-lived states of the ribosome in different stages of its work cycle making proteins. Applications in the study of many other molecular machines are possible.

The Natural Sciences Division invites you to join us in the Higley Auditorium from 11:10 a.m. - noon for this amazing opportunity and discussion. We hope to see you there for this exciting presentation!

Nobel Laureate in chemistry and professor of biochemistry and molecular biophysics and biological sciences at Columbia University Irving Medical Center, Joachim Frank will visit Kenyon for several presentations on Sept. 17. The second of these presentations will be on the processes and impact of cryogenic electron microscopy.

Cryogenic electron microscopy (cryo-EM) has transformed the way we can study biological molecules as it enables us to determine structure of molecules freely suspended in solution (as “single particles”), and to gauge the way they change their shape as they interact with one another in the cell. Freezing, by plunging the sample rapidly into a cryogen at liquid nitrogen temperature, is necessary to trap the molecules in a fixed position in vitreous ice for imaging and to reduce the damage inflicted by the electrons in the process.

Following the introduction of novel cameras for detecting single electrons, near-atomic resolution has been achieved for many molecules and molecular machines of biomedical relevance, including ion channels and receptors. Most recently cryo-EM has contributed in major ways to the development of vaccines and cures for COVID-19.

The Natural Sciences Division invites you to join us in the Oden Auditorium from 7 - 8 p.m. for the second of these two presentations from Nobel Laureate Joachim Frank. This presentation is open to all members of the Kenyon community. We hope to see you there for this exciting presentation!

The soil dwelling bacterium Myxococcus xanthus is an amazing organism that uses collective motility to hunt in giant packs when near prey and to form beautiful and protective macroscopic structures comprising millions of cells when food is scarce. I will present an overview of how these cells move and how they regulate that motion to produce different phases of collective behavior. Inspired by recent work on active matter and the physics liquid crystals, I will discuss experiments that reveal how these cells generate nematic order, how defect structure can dictate global behavior, how transient polar states govern the ultimate dynamics, and how cells actively tune the Péclet number of the population to drive a phase transition from a gas-like flocking state to an aggregated liquid-droplet state during starvation.

The Natural Sciences Division invites you to join us in Hayes Hall 109 on Thursday, Sept. 19, at 11:10 a.m. for this presentation from Joshua Shaevitz, professor of physics and biophysics at Princeton University. Lunch will be available after the talk for attendees who wish to stay and meet with Shaevitz. We also invite students to meet Shaevitz on Wednesday, Sept. 18, at 4 p.m. in Mather 306 for an info session on science careers and graduate school careers. We hope to see you there!

The magneto-optical Kerr effect (MOKE) occurs when linearly polarized incident light changes its polarization state of the reflected light due to its interaction with a magnetic sample. In general, the reflected light off of a sample, when subjected to a magnetic field, will alter its polarization from linear to elliptically-polarized light. This polarization change can be described and measured via the Kerr rotation and Kerr ellipticity parameters, which together provide insights on the magnetic behavior of the sample. Such measurements will be necessary to advance our knowledge on magnetic materials that are potential candidates to advance quantum computing and optoelectronic devices. I am proposing to build a spectroscopic MOKE experiment to investigate the Kerr effect of interesting magnetic materials. This will involve assembling several optical components, performing optical alignment, integrating electronics and writing the necessary LabVIEW codes to fully automate the MOKE system. Finally, the spectra of magnetic materials obtained by MOKE and ellipsometry will be analyzed to recover the dielectric tensor, which is needed to fully characterize the optical, electrical and magnetic properties of the material.

Join us on Friday, Sept. 27, for the last 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!

How can we experimentally verify processes that happen at thousands of degrees and millions of atmospheres of pressure? The field of High Energy Density Physics (HEDP) seeks to create and measure interactions of extremely dense (and often hot) matter in the laboratory. At these conditions, inter-atomic interactions become important, and the matter has characteristics found in plasma physics, condensed matter physics, and nuclear physics. One facility that can create such conditions is the Laboratory for Laser Energetics (LLE) in Rochester, NY. This laser is 70 meters long and produces 30,000 joules of energy in 1 billionth of a second. Experiments investigate conditions and materials relevant to planetary cores, industrial applications, and nuclear fusion. Inertial confinement fusion (ICF) involves using lasers to compress a capsule filled with liquid fuel. When the fuel is hot and dense enough, the atoms will overcome repulsion and create a fusion reaction. This talk will give an overview of my experience in the fields of HEDP and ICF. 

Join us on Friday, Oct. 4, for this exciting presentation from Margaret Huff, postdoctoral associate at the Los Alamos National Laboratory. 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!

Back in 2016, Aharonov et al. showed that, in an experiment involving both quantum state preparation and post-selection, quantum particles can apparently violate the "pigeonhole principle." That is, three particles (pigeons) can be distributed among two boxes (pigeonholes), and yet no two particles are ever found in the same box. It turns out that this example is just one of an infinite class of paradoxical relations among quantum particles. We will examine a few of these, including an Escher-like staircase of particle energies, quantum plane maps that require more than four colors, and an experimental situation in which 1+1 is not always 2. How does such quantum paradoxical knowledge arise, and what does it teach us?

Join us on Friday, Oct. 18, for this exciting Family Weekend presentation from our own Professor Benjamin Schumacher. 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!

During this week's physics colloquium, five Kenyon faculty members will summarize the importance of the 2024 Nobel prizes announced recently. Professors Wade Powell (biology), Maddie Wade (physics), Sheryl Hemkin (chemistry), Pashmina Murthy (English) and Daniel Kolliner (economics) will discuss the physiology, physics, chemistry, English literature and economics prizes, respectively.

Join us on Friday, Oct. 25, for this exciting presentation from members of Kenyon's faculty. 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 sugar skulls to decorate and candy to eat. So, grab your pointy hats, magical staffs and burbling cauldrons and come to Hayes 211/213 for a Mumummemberable lunch.

Lunch will be available in Hayes 216 from 11:45 a.m. to 12:15 p.m. on Friday, Nov. 1, and the doors will open for the party at 12:10 p.m. in Hayes 211/213. We hope to see you there!

In nature, matter naturally exists in one of four states. The most common (and perhaps least familiar) of these states is a plasma; an ionized gas composed of ions, electrons and neutral particles. This state of matter exhibits several complex phenomena and has numerous practical applications, impacting nearly every aspect of our everyday lives. Nearly all plasmas that occur, both in nature and in the laboratory setting, contain small particles of matter (dust).  When this particulate matter enters a plasma, it becomes charged through interactions with the electrons and ions in the background plasma. Once charged, this third charged species fully interacts with the other plasma components and self-consistently alters the properties of the surrounding plasma. The resulting system is known as a dusty plasma, a non-linear system that is notably more complex than the traditional plasma and supports a wide range of new plasma phenomena including new wave modes and strongly coupled phenomena.  

In ground-based experiments, the high mass of the dust leads to sedimentation effects, resulting in the dusty plasma system being compressed. To reduce sedimentation effects, it is necessary to perform experiments in a microgravity environment, such as in the ISS based experiment facility "Plasma-Kristall-4" (PK-4). In the PK-4 facility, particles are injected into a dc glow discharge plasma and flow along an axial electric field.  Upon the application of polarity switching (a periodic oscillation of the electric field), a sudden change in the bulk motion and spatial ordering of the dust is observed. In some cases, this change is accompanied by a change in the thermal state of the dust component.

In this talk, Jeremiah Williams, professor of physics at Wittenberg University and =program director in plasma physics at the U.S. National Science Foundation, will present a brief introduction to plasmas and dusty plasmas, highlighting how these systems are relevant to your everyday lives and provide a unique system to study a wide range of physical phenomena. He will also present the results of a series of experiments and numerical simulations to understand the change in the thermal state that has been observed in the PK-4 microgravity laboratory on the International Space Station.

Join us on Friday, Nov. 8, for this exciting presentation from Williams. 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 group motto could be "you don't know the answer until you do the problem”.

There are a set of great questions that pester the cosmologist’s mind: What’s the nature of dark matter? What’s the nature of dark energy? What defines the initial conditions of the Universe?  Simple answers to these questions are easy to rule out; more complicated guesses generally require (1) reducing the scope of the problem to find analytic or semi-analytic approximation or (2) robust numerical simulations.  In this talk, I’ll introduce some of the answers (and hints) our group has uncovered recently when we tackle these problems head-on.

Join us on Friday, Nov. 15, for this exciting presentation from our own Professor Tom Giblin. 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!