The University of Mississippi
Department of Physics and Astronomy

Seminars/Colloquia, Fall 2016

Unless noted otherwise, Tuesday Colloquia are at 4:00 PM
with refreshments served 15 minutes before each colloquium.

Scheduling for additional seminars will vary.

Date/Place Speaker Title (and link to abstract)
Tue, Aug 23
Lewis 101
   
Tue, Aug 30
Lewis 101
Department Faculty, Staff and Students Ice Cream Social (PDF)
Tue, Sep 6
Lewis 101
  Orals for the Comprehensive Exam
Tue, Sep 13
Lewis 101
Michael S Turner
Kavli Institute for Cosmological Physics
University of Chicago
The Big Picture: What We Know About How the Universe Began and What We Are Trying to Find Out
PowerPoint (165 MB) PDF (117 MB)
Tue, Sep 20
Lewis 101
Don Summers et al.
Department of Physics and Astronomy
University of Mississippi
Fascinating Physics Demonstrations
Tue, Sep 27
Lewis 101
Don Summers Presenting
Department of Physics and Astronomy
University of Mississippi
Powers of Ten
Tue, Oct 4
Lewis 101
   
Tue, Oct 11
Lewis 101
Mike Reep and Scott Watkins
Department of Physics and Astronomy
University of Mississippi
Machine Shop Physics
Tue, Oct 18
Lewis 101
Chandrima Chatterjee
Department of Physics and Astronomy
University of Mississippi
Experimental Investigation of Impurities and Their Effect on Acousto-Electric Properties of Lithium Niobate
Tue, Oct 25
Lewis 101
Matteo Rini
Deputy Editor
American Physical Society
Science Communication: Take Charge of It!
PowerPoint or PDF (21 MB each)
Tue, Nov 1
Lewis 101
Jeremy Sakstein
Department of Physics and Astronomy
University of Pennsylvania
Novel Tests of Gravity Using Astrophysics
(PDF)
Tue, Nov 8
Lewis 101
Mairi Sakellariadou
Department of Physics
King's College — London
Unweaving the Fabric of the Universe
Fri, Nov 11
Lewis 101
Gregory Cook
Department of Physics
Wake Forest University
Gravitational Waves from Colliding Black Holes: An Historical Perspective
(PDF)
Tue, Nov 15
Lewis 101
Karelle Siellez
Center for Relativistic Astrophysics
Georgia Institute of Technology
The Coincidence Between Gamma-Ray Bursts and Gravitational Waves: the Dawn of the Multi-Messenger Era!
PowerPoint (117 MB) PDF (33 MB)
Tue, Nov 22
Lewis 101
Thomas Turkey
Department of Nutrition
Virginia Tech
Continuing Advantages of a Vegetarian Diet
Tue, Nov 29
Lewis 101
PGSA
Department of Physics and Astronomy
University of Mississippi
Physics Graduate Students Association General Meeting
Tue, Dec 06
Lewis 101
Final Exam Week  

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Abstracts of Talks


Michael S Turner
Kavli Institute for Cosmological Physics
University of Chicago

The Big Picture: What We Know About How the Universe Began and What We Are Trying to Find Out

Today the Universe is made out of dark matter, dark energy and a small amount of ordinary matter (the atoms we are made of). We can trace the history of the Universe back to when it was a microsecond and was a formless quark soup. We now have good evidence for an early burst of tremendous expansion (inflation) that stretched sub-atomic quantum fluctuations to astrophysical size and created the seeds for galaxies. But there is much to figure out, including what dark matter is made of, what the nature of the mysterious dark energy is, and when inflation took place.


Don Summers et al.
Department of Physics and Astronomy
University of Mississippi

Fascinating Physics Demonstrations

Fifty minutes of fascinating physics demonstrations, including milk jug rockets, will be presented.


Don Summers Presenting
Department of Physics and Astronomy
University of Mississippi

Powers of Ten

Powers of Ten illustrates the universe as an arena of both continuity and change, of everyday picnics and cosmic mystery. It begins with a close-up shot of a man sleeping near the lakeside in Chicago, viewed from one meter away. The landscape steadily moves out until it reveals the edge of the known universe. Then, at a rate of 10-to-the-tenth meters per second, the film takes us towards Earth again, continuing back to the sleeping man's hand and eventually down to the level of a carbon atom.


Mike Reep and Scott Watkins
Department of Physics and Astronomy
University of Mississippi

Machine Shop Physics

Experimental physics depends on instrumentation made in the University of Mississippi's Physics machine shop. Instruments made for Acoustics, Atmospheric physics, Condensed Matter physics, and Particle physics will be shown.


Chandrima Chatterjee
Department of Physics and Astronomy
University of Mississippi

Experimental Investigation of Impurities and Their Effect on Acousto-Electric Properties of Lithium Niobate

The functional parameters of Lithium niobate that is used in various acousto-opto-electronic applications are questionable. The nonclassical nonlinear effect such as “acoustical memory” is not explained at full. Despite there being publications on crystal defects in Lithium niobate, the relationship between the defects and Acoustical Memory has not yet been established. Previous publications analyzed the Acoustical Memory effect without going into the microstructural detail of the level of point defects. The purpose of this research is to establish a connection between the microscopic point defects and the macroscopic nonlinear phenomena. The present research aims at finding new crystal characteristics including the identification of impurities and point defects, the distribution of the defects along the optical crystallographic z axis, and in a direction normal to the z axis. Bulk crystals and wafers are studied. The impurities are identified by their characteristic lines in the photoluminescence spectra, which are taken at room temperature in a range of 350 to 900 nm. The spectra reveal the following point defects: Ar, Ba, Cs, F-color center, Rb, Ru, Sn, Fe, K, Li, O, Nb, Kr, NbLi4+, Xe, etc. The peak corresponding to the F-center is found at 400.429 nm and has the highest number of photon counts. Further, the samples are shifted with a step of tens of microns along the z-axes or normal to it. This optical scanning allows to find a distribution of the impurities in the samples. The photon counts changes with crystal position for some impurities. The distribution of these defects is observed as peaks and valleys. The results may be used to discover the physical mechanisms behind nonclassical nonlinear phenomena in Lithium niobate.


Matteo Rini
Deputy Editor
American Physical Society

Science Communication: Take Charge of It!

Scientists have a responsibility to share the meaning and implications of their work, but receive little training in communication, and often feel unprepared to communicate with the public, the media, public officers and others outside their own field. In this talk, I will discuss how our journal Physics (htttp://physics.aps.org) strives to communicate research to a broad audience and share some thoughts and tips on science communication from my experience as a writer, editor, press officer and scientific consultant to policy makers.


Jeremy Sakstein
Department of Physics and Astronomy
University of Pennsylvania

Novel Tests of Gravity Using Astrophysics

The expansion of the Universe is accelerating and we have little to no idea why! This has led to a proliferation of alternative theories of gravity that are not general relativity as one possible explanation. Classical alternatives are quickly ruled out by solar system tests but modern theories can evade them by utilising screening mechanisms. This has led to an active program developing new and novel tests of gravity by looking for objects that are not fully screened.

In this talk, I will review the cosmological constant problem and modern alternative gravity theories before going on to describe some of my work looking for new and novel ways of testing gravity using objects such as dwarf stars, neutron stars, and pulsating Cepheids.


Mairi Sakellariadou
Department of Physics
King's College — London

Unweaving the Fabric of the Universe

Our conventional understanding of space-time, as well as our notion of geometry, break down once we attempt to describe the very early stages of the evolution of our universe. The extreme physical conditions near the Big Bang necessitate an intimate interplay between physics and mathematics. The main challenge is the construction of a theory of quantum gravity, the long-sought unification of Einstein's general relativity with quantum mechanics. There are several attempts to formulate such a theory; they can be tested against experimental and observational results coming from high energy physics and astrophysics, leading to a remarkable interplay between gravity, particle physics and cosmology.


Gregory Cook
Department of Physics
Wake Forest University

Gravitational Waves from Colliding Black Holes: An Historical Perspective

The landmark first direct detection of gravitational waves was announced on Feb. 11, 2016. The detection itself occurred on Sept. 14, 2015 and was the result of the collision of two black holes that happened around a billion years ago. The event marks a turning point in decades of work by hundreds of researchers. The goal of this talk is to provide at least a partial historical account of the research that lead to the detection and interpretation of this event. As a numerical relativist, my perspective will emphasize the work aimed at simulating black-hole collisions on computers. I have been involved in all aspects of the simulation of black-hole binary collisions for nearly 3 decades, with my work focusing primarily on the modeling of initial data for the simulations. However, I will try to give fair coverage of the broader theoretical and computational work involved, and a taste of the experimental milestones leading up to the detection. If time allows, I will also discuss some of my recent work exploring the ring-down signal produced by numerical simulations.


Karelle Siellez
Center for Relativistic Astrophysics
Georgia Institute of Technology

The Coincidence Between Gamma-Ray Bursts and Gravitational Waves: the Dawn of the Multi-Messenger Era!

Last year, while we celebrated the 100th anniversary of the Theory of the General Relativity of Einstein, we also detected the first direct observation of Gravitational Waves. LIGO opened the new area of Gravitational Wave Astrophysics with the detection of the coalescence of two black holes. Neutron star mergers (either double neutron star or neutron star - black hole systems) and collapsing massive stars are the next candidates for the detection of Gravitational Waves. They are though to be also the progenitor of respectively short and long Gamma-Ray Bursts. A detection in coincidence of both the Gravitational Waves and the electromagnetic emission would open the era of multimessenger astrophysics.

To detect those coincidences between GRB and GW, LIGO uses a different analysis that searches for a GW triggers coincident within some time window and sky position of a GRB in nearly real time thanks to the GCN sent by the satellite. We estimated the rate of coincident events that could be detected during the next run of O2 using observations in one hand and Monte Carlo simulations on the other. The small number of coincidence could be improved by using the untriggered GRBs missed by the Fermi GBM satellite. Thanks to a new code developed by the GBM team, we will discuss about the new kind of coincident detection that we could obtain.

This talk will describe the search of Gravitational Waves associated to GRBs. We will show the motivations and analysis made for the untriggered searches as well as the implication of those untriggered GRB on the expected rate of coincident event, the classification of long and short GRBs, and the possible new kind of progenitor for short GRBs at low redshift.