Physics and Astronomy
Contact
Department Chair:
Yumi Ijiri

Administrative Assistant:
Diane Doman

Department Email:


Phone: (440) 775-8330
Fax: (440) 775-6379

Location:
Wright Laboratory of Physics
110 N. Professor St.
Oberlin, OH, 44074

Physics and Astronomy Lecture Series

Physics and Astronomy Lecture Series

2013-2014

September

19 (Thursday) 4:35 pm

Speaker:  Dr. Daniel F. Styer, Professor, Department of Physics and Astronomy, Oberlin College
Title:  And Yet It Moves:  Quantal Interference of Charged Particles and the Aharanov-Bohm Effect
Abstract:  In quantum mechanics, a magnetic field can affect the motion of a charged particle even when that particle has zero probability of existing where the field exists.  In contrast, that magnetic field does not affect the mean position of the particle, nor the uncertainty, nor any moment of the position.
Location:  Wright 201


October

14 (Thursday) 4:35 pm

Speaker: Dr. Amy Graves, Professor, Department of Physics and Astronomy, Swarthmore College
Title:  Of Rice and Men: Jamming of Particles and People
Abstract:  Jamming is a phenomenon that applies both to rice and men .. which is to say it applies to inert grains of matter and to thinking creatures.  A jam can be frustrating or even lethal, as in situations of people trapped in a crowded venue.  A jam can alternatively be beneficial, as in situations when blood cells need to be sorted, or soft robots need to move around.  Jamming is an active field in theoretical condensed matter physics, where both rules-based and force-based simulations yield insights that match up well with experiment.  Our group has run C++ simulations of jamming in the presence of fixed obstacles, and a few novel results of this work will be discussed.  We will also discuss dynamical simulations that we've written in Easy Java Simulations.  These have the advantage of being easy to build, even for the young student who is a novice programmer.
Location:  Wright 201


November

7 (Thursday) 4:35 pm

Speaker:  Dr. Thomas Lemberger, Professor,  Department of Physics, Ohio State University
Title:  Superconductivity - Past, Present, and Future
Abstract:  Superconductivity is a many-particle quantum ground state with zero electrical resistivity.  Discovered in 1911 in thin wires of Hg at 4 Kelvin, it was explained theoretically only after 46 years of effort.  The physics is broader than electrons in metals - the concept of spontaneous symmetry breaking arose in the theory of superconductivity and lead directly to the "Higgs mechanism: for giving particles mass.  Practical applications include high-field magnets, fault-current limiters, electric filters for cell-phone repeaters, and levitated trains.  This talk will run through phenomenology of superconductors, underlying concepts, and present day research topics including some of the research being done in Professor Lemberber's lab.
Location:  Wright 201

 

February

13 (Thursday) 4:35 pm

Speaker:  Dr. Daniel Homan, Department of Physics, Denison University
Title:  The Acceleration of Relativistic Jets in Active Galaxies
Abstract:  With lifetimes of hundreds of millions of years and luminosities exceeding that of entire large galaxies, extragalactic radio jets are the most powerful, sustained phenomena in the Universe. These relativistic jets can flow in narrow beams for hundreds of thousands of light years, from the very center of the galaxy to well beyond its boundaries before terminating in large, inflated 'radio lobes'. The jets are believed to be powered by the infall of matter onto a super-massive black hole at the heart of the galaxy, but the process of acceleration and collimation of these jets is still poorly understood. We present studies of the motion of jets very near their origin, within a few tens of light years of the super-massive black hole system. By tracking these motions over time, we have produced the first large sample of measurements of acceleration in relativistic jets. The problems associated with understanding motion which is very near the speed of light (> 0.99 c) and directed nearly towards the observer will also be considered.
Location:  Wright 201


27 (Thursday) 4:35 pm

Speaker:  Dr. Daniel Hemberger, OC '07, Postdoctoral Scholar, California Institute of Technology
Title:  Detecting Gravitational Waves from Binary Black Holes
Abstract:  Binary black holes are one of the most promising science targets for the advanced Laser Interferometer Gravitational Wave Observatory (aLIGO), which is expected to be operational later in 2014. The detections made by aLIGO (or lack thereof) will provide stringent tests of Einstein's theory of General Relativity and our understanding of many astrophysical processes. It will be much easier for aLIGO to make a detection if there is a comprehensive bank of expected waveforms, but generating sufficiently many accurate waveforms from numerical simulations of binary black holes can be computationally prohibitive. However, using reduced order modeling, we can make the most efficient use of numerical relativity and provide aLIGO with the predictions that are needed to maximize its detection probability.
Location:  Wright 201


March

13 (Thursday) 4:35 pm

Speaker:  Dr. Christian Fink, Visiting Assistant Professor, Department of Physics and Astronomy, Ohio Wesleyan University
Title:  How Neuronal Synchrony Can Help to Explain the Mystery of Sleep
Abstract:  Sleep is a requirement for virtually every known animal species, yet its purpose remains a mystery. There are many competing theories to explain the functions of sleep, but one that has garnered especially high interest in the past few decades is known as the synaptic renormalization theory, which posits that sleep is necessary to maintain homeostasis within the brain. Though this theory is supported by numerous empirical observations, it is currently incomplete, for it lacks a biophysical mechanism to explain these observations. In this talk, I will propose a viable biophysical mechanism to help complete the synaptic renormalization theory. Simulation results will be presented showing that the dynamical effects of acetylcholine, in combination with a spike-timing dependent plasticity rule, can reproduce the central tenets of the synaptic renormalization theory. Fundamental concepts in neuroscience will be reviewed as a basis for understanding this work, and the fruitfulness of viewing the brain as a dynamical system will be highlighted.
Location:  Wright 201


April

10 (Thursday) 4:35 pm

Speaker:  Greg Howland, OC '07, Graduate Student, Department of Physics and Astronomy, University of Rochester
Title:  Compressive Sensing for Quantum Imaging
Abstract:  Compressive sensing (CS) is an exciting new measurement technique that exploits compressibility to recover many-dimensional signals from very few measurements. Remarkably, the best measurements an experimenter can use are random. I will discuss the application of CS techniques to current problems in quantum imaging. These range from the very applied, such as photon-counting lidar, to the very fundamental, as CS provides an interesting perspective on the uncertainty principle.
Location:  Wright 201

14 (Monday) 4:35 pm

Speaker:  Kathryn Hasz, Senior Honors Student in Physics, Oberlin College
Title:  Polarization Analyzed Small Angle Neutron Scattering of Ferrite Nanoparticles
Abstract:  Magnetic nanoparticles have many potential uses in areas including data storage and biomedicine. However, the properties of these nanoparticles are still not well understood. This talk will focus on two model systems of magnetic nanoparticles, one of iron oxide and one of cobalt iron oxide. We investigated the properties of these particles using a technique known as polarization analyzed small angle neutron scattering (PASANS). This technique revealed that the magnetic interactions of these particles vary with temperature and applied magnetic field, with some more complex magnetic structure forming under certain conditions.
Location:  Wright 201

16 (Wednesday) 4:35 pm

Speaker:  Chetan Poudel, Senior Honors Student in Physics, Oberlin College
Title:  Separating Magnetic Nanoparticles Using a Halbach Array:  Creation of a New Device for Biomedical Applications
Abstract:  Magnetic nanoparticles are extremely tiny particles that have become topics of intense scientific research in recent years, for their potential applications in biomedicine.  In most of these biomedical applications, there is a critical need to ensure uniformity of nanoparticles in terms of their size and magnetic properties.  In this talk, we will describe our creation of a new device and technique for the separation of these magnetic nanoparticles, using a clever adaptation of existing technology.  We will investigate the properties of nanoparticles, the process of separation in our device and our experimental results from x-ray scattering and magnetometry confirming the utility of our device over existing magnetic separation technologies.
Location:  Wright 201

18 (Friday) 4:35 pm

Speaker:  Jocienne Nelson, Senior Honors Student in Physics, Oberlin College
Title:  Overtone Spectroscopy of Hydrogen Trapped in Metal-Organic Frameworks
Abstract:  Metal-Organic Frameworks (MOFs) are an exciting class of materials with applications that include hydrogen storage, gas separation and carbon sequestration. Their highly porous crystalline structure allows them to effectively trap gases like molecular sponges. They are made of metal complexes linked by organic chains. In principle, it is possible to select the metal and linker units in order to build the ideal MOF for a specific application. Because of the multitude of possible structures it is essential to understand the quantum mechanical interactions to guide the building of new structures. These interactions are analyzed using infrared spectroscopy. Overtone spectroscopy is the study of the higher harmonics of trapped hydrogen. Looking in these frequency regions is interesting both because it avoids background noise due to the host materials themselves and provides extra information with which to analyze the trapped molecules’ behavior.
Location:  Wright 201

21 (Monday) 4:35 pm

Speaker:  Benjamin Lemberger, Senior Honors Student in Physics, Oberlin College
Title:  Special Symmetries in a Bouncing Universe
Abstract:  The Mixmaster Universe is a solution to Einstein's equations which is relevant to the study of spacetime near a singularity. This solution exhibits exotic bouncing behavior which is caused by its own curvature.  These bounces are well understood, but we present a new interpretation of them as an endless sequence of small transitions towards, punctuated by the occasional large transition away from, a certain type of symmetry called algebraic speciality.
Location:  Wright 201

23 (Wednesday) 4:35 pm

Speaker:  Zachary Mark, Senior Honors Student in Physics, Oberlin College
Title:  Musical Black Holes: The Songs of the Kerr-Newman Spacetime
Abstract:  Are charged, spinning black holes (Kerr-Newman spacetimes) stable? How might we search for these exotic objects using modern gravitational wave observatories such as Advanced LIGO? These questions are most easily approached by studying small perturbations to the Kerr-Newman spacetime. Much like a drum can only produce a special set of notes, perturbations to an isolated black hole spacetime can only evolve with a special set of frequencies called quasinormal mode frequencies. In this talk, we present calculations of the quasinormal mode frequencies of a charged, spinning black hole in the limit of small charge.  From a practical standpoint, this set of frequencies is a unique signature of the black hole that can be searched for in Advanced LIGO data. Theoretically, these frequencies provide us with valuable evidence for the stability of the Kerr-Newman spacetime.
Location:  Wright 201

Department of Physics and Astronomy Lecture Series speakers from past years.