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.
April 23, 2014
Rachel Lee Pincus, Isaac Khader, Aaron McCray-Goldsmith, Logan Emery
Joel Franklin ('95), Reed College
The 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 school
The 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 University
Reenvisioning the Invisible: An Alternative Approach to the Dark-Matter Puzzle
Overwhelming 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 College
Applied Physics and Impact Cratering
Planetary 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 College
Looking for black holes in the dark
I 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 Tech
From Huygens' Clocks to Hurricanes
Many 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 Study
An Inconvenient Truth About 'Biosignatures' Involving Two Chemical Species in Exoplanets
Despite 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 University
Muon g-2: precision particle physics at Fermilab
I 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.
During this seminar, students will report on their recent activities in physics away from Reed College.
Andrew McNutt, Phil Jahelka, Prakher Bajpai, Tobias Koppel
Gregory Kohler, Aya Maguire, Anya Demko, Allison Morgan
Rachel Lee Pincus, Isaac Khader, Aaron McCray-Goldsmith, Logan Emery
Rachel Lee Pincus
Huy Nguyen, Stu Pickell, Luke Liechty