Spring 2018 Physics Colloquium

Monday, January 29th
Q&A with the Glover Lecturer - Gabriela Gonzalez

Tome Hall Library
Lunch provided

Thursday, Febrary 15th
Physics 491/492 - Updates to the Major

The Department of Physics and Astronomy has made significant change to the way in which our senior capstone experience will be offered. We would like to explain the changes that will be adopted starting in the fall of 2018 and answer any questions that you might have.  Additionally, a few faculty members will give a brief presentation on their current research and any opportunities available in their lab.

Tome 115
Pizza provided

Tuesday, April 24th
Senior Research Presentations

Natalie G. Ferris & Ruth A. Strauss - “Double-Slit Interference with Partially-Coherent Light”
To analyze double-slit interference using a quantum light source, we must first fully understand this type of interference with a classical, partially-coherent source of light. Experimentally, our light source consists of an expanded Helium Neon laser incident on a rotating white card. The size of the source is controlled with a variable width slit. We measure the intensity of the light after it passes through a double-slit aperture. The visibility of the observed interference pattern depends on the angular size of our light source. We show the relationship between angular source size and visibility for partially-coherent light sources. The experimental data demonstrates shortcomings of the standard theoretical description, particularly for low visibilities. To resolve this, we develop a more complete theoretical model that has better agreement with the experimental data. We discuss implications of these results for ghost interference, a phenomenon where an interference pattern is observed in a beam of light that does not actually pass through a diffracting mask such as a double slit.

Veronica Marie Rodriguez - “The Use of Automated Planetariums in Introductory Undergraduate Astronomy Education”
This project focuses on developing and evaluating the effectiveness of short planetarium shows on the Spitz ATM-4 Theater Automation System of Dickinson College's Kanev Planetarium; specifically centered on programs intended for use in introductory undergraduate astronomy courses.  The programs have been tested on volunteer groups including Dickinson students as well as Carlisle residents.  Now completed, the programs are available for use by the Dickinson Department of Physics and Astronomy as aids for instructors or as a basis for further research.

Stafford Lecture Room
Lunch provided

Thursday, April 26th
Senior Research Presentations

Ellis Johnson & Matt Persick - “Light Pollution: The Mathematical Model and Theoretical Analysis”
The production of light has served as a milestone in human technological advancement however, it also has demonstrated how light can impact the world we live in. Light pollution, or the brightening of the night sky due to wasted energy and inefficient lighting from artificial sources is one of these impacts. Using the town of Carlisle Pennsylvania and Shippensburg Pennsylvania as a case study, this talk will address how light produced from various man-made sources can impact sky brightness and how alterations in outdoor lighting sources can minimize the effects of light pollution. By extrapolating the output of a single outdoor light source we developed broad-based assumptions about the light emitted into the sky by the entire town of Carlisle and compared the results to Shippensburg to verify our model. By comparing the output of the model to primary and secondary observational data sets from a Sky Quality Meter, we can display the light pollution with accuracy. Further research leads us to apply our model to surrounding towns in Pennsylvania.

Ralph Lawrence Hernandez & Zifan Lu - “Photometric Analysis of RR Lyrae Variable GM Orionis”
RR Lyrae stars are pulsating variables that have been used in determining the cosmic distance scale. There are currently seven known sets of observations of the RR lyrae Star GM Orionis since 1935. Taken at face value, the observations within the last 80 years indicate that GM Orionis, on average, has decreased in magnitude (an increase in brightness)—a rare phenomenon for the RR Lyrae Variable class. In our research, we will discuss the steps we took to analyze the most recent set of data of GM Orionis taken at the NURO Observatory during the Fall of 2017 and Spring of 2018. Our objective is to acquire a real magnitude, compare it with the historical observations, and test to see if the phenomenon is continuing today.

Erin Wynne - “Using an Arduino in a Coupled Logistic Map Circuit to Record Bifurcations and Chaos”
The logistic map is a simple non-linear dynamical system used to model the time-discrete growth of a population. In a previous project, a circuit was built that successfully reproduces the behavior of a system of two coupled logistic maps. However, the major limitation of this project was its non-automated data collection technique. In this project, the Arduino Uno microcontroller was used to improve data collection by running the timing of the circuit, incrementing the coupling voltage, and triggering data collection. The experimental bifurcation diagrams produced were compared to numerical simulations and found to have substantial agreement. One difference pertains to the selection of initial conditions. In the experiment, where we have no control of initial conditions, we found hysteresis behavior within the chaotic regime that was not present in simulations. Basic chaotic principles such as period doubling and the onset of chaos, in addition to more exotic behaviors such as “almost synchronized” and “anti-synchronized” chaos were observed in the experimental data. We are also able to explore the interaction between a chaotic and a cyclic oscillator.

Tome 115
Lunch provided

Friday, May 4th
Physics and Astronomy End of Year Picnic

Tome Hall Back Lawn (Rain Location: Tome 115)
Pizza provided by the College Farm