# Physics

## Seminars in Spring 2014

All seminars are held at 4:10 PM in Physics 123, unless otherwise noted.
Refreshments will be served at 4:00 PM.

Jan 29 Joel Franklin ('95), Reed CollegeThe Motion of Two Charged Particles Morris (Wright) Copeland ('82), Oregon Episcopal School. Matt Price ('93), Lakeridge High School. Amy Feller, Wilson High School. Bob Sauer, Catlin Gable.Teaching physics in high schoolThe panelists will discuss their experiences teaching physics in high school--how they got into the field, what it is like as a career, and some things they have learned.  Whether or not you are contemplating a career in education, this should be a very interesting discussion, with audience participation encouraged. Search Candidate: Brooks Thomas, Carleton UniversityReenvisioning the Invisible: An Alternative Approach to the Dark-Matter PuzzleOverwhelming evidence now suggests that the majority of the matter in our universe consists of some exotic "stuff" that neither emits nor absorbs light, yet makes its presence felt via its gravitational pull on normal matter.  Over the years, a number of simple and elegant ideas have been advanced to explain the nature and origin of this "dark matter."  However, a variety of puzzling experimental results and tantalizing potential signals have recently emerged which are difficult for these simple proposals to explain. These results have motivated more complicated solutions to dark-matter problem, and have even given birth to the idea that our universe might contain a whole "dark sector" comprising a variety of different particles with different properties.  In this talk, I'll describe an alternative perspective on the dark-matter puzzle -- one which in some sense represents the most general "bottom-up" approach to that puzzle which can possibly be imagined.  This new perspective brings to light a variety of new, viable scenarios for dark matter whose unusual and distinctive experimental consequences are only beginning to be explored. Search Candidate: Kassandra Martin-Wells, Carleton CollegeApplied Physics and Impact CrateringPlanetary science is a rich field for applied physics.  In this talk, we will explore physics questions related to radar remote sensing of planetary surfaces, as well as applications to the study of impact cratering mechanics.  Specifically, we will discuss models of microwave radiation off of the lunar surface and how radar observations of the scars left by impact ejecta can help us better understand the likelihood of panspermia--the hypothesis that it might be possible to transport simple life between Solar System bodies via meteoroids.  Our discussion will also touch on the dynamical evolution of such meteoroids once they reach space. Search Candidate: Steve Drasco, Grinnell CollegeLooking for black holes in the darkI will talk about black holes and efforts to search for them with gravitational-wave detectors.  I will focus on scenarios that are especially ideal for the new generation of detectors currently under construction.  These efforts could lead to our first observations of two-body systems with orbit-like motion that is wildly different from familiar ellipses made famous by Kepler and Newton.  Past, present, and future undergraduate participation will be a recurring theme. Search Candidate: Daniel Borrero, Georgia TechFrom Huygens' Clocks to HurricanesMany systems in science and engineering are governed by nonlinear evolution equations. Starting with the familiar case of the simple pendulum, I will discuss some of the ways that nonlinear systems differ from linear ones and discuss how nonlinearity can lead to unexpected behavior. One famous example is the so-called "butterfly effect" where small differences in initial conditions can lead drastically different long term behavior. I will explain this in the context of my work on the synchronization mechanisms of metronomes coupled by a common movable platform, a phenomenon first discovered by Huygen's in the 1665. Another consequence of nonlinearity is that systems can have multiple solutions for a given set of parameters. The competition between solutions often leads to very complicated spatial and temporal dynamics. I will discuss recent advances in identifying a special class of solutions of the Navier-Stokes equations (the governing equations for fluid flows) and how these are being used being used to shed light on one of the oldest open problems in mechanics, the study of hydrodynamic turbulence. Dave Spiegel, Institute for Advanced StudyAn Inconvenient Truth About 'Biosignatures' Involving Two Chemical Species in ExoplanetsDespite the many recent announcements in the popular press of 'Earth-twin' exoplanet discoveries, no actual Earth twins have been found yet; but it's reasonably likely that in the next few years an object might be discovered that plausibly deserves this moniker.  However, learning anything other than the planet’s existence and its most fundamental properties such as mass and radius will be extremely difficult.  Fundamental physics (photon noise) will prevent us from any detailed analysis of the planet’s atmosphere.  Even worse, there are false positives that can spoof biomarkers even if multiple chemical species are detected in a spectrum.  In this talk, I will discuss how it is possible to learn about the composition of worlds around other stars, I'll introduce one such false-positive scenario, and I'll present a statistical framework for understanding what we may conclude about the probability of life existing on exoplanets from observations of when life arose here on Earth. Robin Bjorkquist, Cornell UniversityMuon g-2: precision particle physics at FermilabI work on the Muon g-2 experiment, a precision particle physics experiment which is being built at Fermilab. We plan to measure the anomalous magnetic moment of the muon to 0.14 ppm precision, a factor of four improvement over the current experimental value. Our measurement is desirable from the standpoint of particle physics because it will be a fine probe of the standard model, as well as various beyond-the-standard-model physics scenarios. I will give an overview of the experiment -- its purpose, method, and progress so far. I will also talk about my own work simulating the response of the electromagnetic calorimeters. Finally, I will share some thoughts about what it's like to be a graduate student in experimental particle physics, and how I ended up doing this work. Student PresentationDuring this seminar, students will report on their recent activities in physics away from Reed College. Reed physics majors Elizabeth Grace ('15), Millie Dunn ('16), Colleen Werkheiser ('16), Anna Nuxoll ('15), Jacqui Meadows ('16), and Julia Selker ('15) will report on the Women in Physics conference at UC Berkeley in January. Reed physics major Alex Emerman ('14) will report on his activities at CERN in the Fall of 2013. Andrew McNutt, Phil Jahelka, Prakher Bajpai, Tobias KoppelThesis TalksAndrew McNuttNonequivalent Lagrangian Mechanics Phil Jahelka Assessing the Validity of the Envelope Function Approximation Tobias Koppel Demonstrating a Negative Index of Refraction Gregory Kohler, Aya Maguire, Anya Demko, Allison MorganThesis TalksGregory Kohler Quantum Mechanics of the -1/r2 potential Aya Maguire Mapping Dark Matter using Weak Gravitational Lensing Anya Demko Dynamic Stabilization of an Inverted Pendulum Allison Morgan Relativistic Strings and Ehrenfest's Paradox Rachel Lee Pincus, Isaac Khader, Aaron McCray-Goldsmith, Logan EmeryThesis TalksRachel Lee Pincus Photoacoustic Spectroscopy:  A Method for Investigating Weak Molecular Absorption Isaac Khader A Magneto Mechanical Nonlinear System Aaron McCray-GoldsmithKinematics of the Falling Slinky Logan Emery Spectroscopic Characterization of Water Adsorption on Calcium Carbonate and its Astrophysical Implications Huy Nguyen, Stu Pickell, Luke LiechtyThesis TalksHuy NguyenNumerical Solution to the Hubbard Model Stu PickellHolographic QCD in the $D4/D8/\overline{D8}$ Configuration: An Analysis of Closed Strings as Gravitons/Glueballs Luke LiechtyThe Power Output of the Stirling Engine