Fall 2009 Seminars
Seminars are held on Tuesdays, 3:45-4:45pm in SB110, unless otherwise noted. Meet at 3:30 in SB157 for refreshments (refreshments are available even on Tuesdays with no seminar!). See Calvin's Visitor Resources for maps and directions to the Science Building.
Tuesday, September 29
|Smashing New Results: Collisions in the Asteroid Belt||Professor L. Molnar and student Melissa Haegert|
Tuesday, October 6
Snacks at 3:30 in SB157 Seminar class at 3:45 pm
|Tuesday, October 13|
|Tuesday, October 20||Dr. Gyoungho Lee, Associate professor, Department of Physics Education, Seoul National University, Seoul, South Korea; Visiting professor, Department of Physics & Astronomy, Calvin College|
|Tuesday, October 27 Advising Recess||No snacks, seminar class or colloquium|
Friday, October 30 3:30p.m.
|Lie Algebra and the Large Hadron Collider||Dr. Alex Dragt, professor Emeritus, Physics Department, University of Maryland|
|Tuesday, November 3||Snacks at 3:30 in SB157 Seminar class at 3:45 pm|
|Tuesday, November 10||Snacks at 3:30 in SB157 Seminar class at 3:45 pm||
|Tuesday, November 17||
Snacks at 3:30 in SB157 Seminar class at 3:45 pm
|Tuesday, November 24||Giant Galaxies and Glowing Gas||Professor Deb Haarsma and student Luke Leisman|
|Tuesday, December 1||Fun with classical simulations of double inonization of atoms by near-infrared and visible-wavelength lasers||Students Timothy Atallah, Peter Plantinga and Katie Shomsky|
|Tuesday, December 8||Lipids Kinetics and Sucrose: A Sweet Story||Prof. Paul Harper and student Nathan Meyers|
September 29: Smashing New Results: Collisions in the Asteroid Belt
Professor L. Molnar and student Melissa Haegert
The dynamical history of the asteroid belt illuminates key questions about the past, present, and future of the solar system. Asteroid dynamics are driven by three successive processes: 1) violent collisions between asteroids produce families of fragments; 2) absorption and re-emission of sunlight gently modifies the fragments' orbits over hundreds of millions of years; until 3) they reach a resonant location, where interactions with Jupiter or Mars can remove them from the belt in just a few million years. We will discuss the dynamics of four collisional families. Our new discoveries allow us to determine the ages of each; the ages range from 5.7 milliion years for the youthful Karin family to 1500 million years for the ancient Flora family.
October 30: Lie Algebra & the Large Hadron Collider
Dr. Alex Dragt, Professor Emeritus, Physics Department, University of Maryland
Lie algebras were first discovered by mathematicians and extensively studied for their intrinsic beauty. Subsequently physicists learned that Lie algebras are also fundamental to the existence, attributes, and interactions of elementary particles. Elementary particles, always present in nature and particularly abundant in rare forms at the creation of the Universe, are produced and studied in the laboratory with the aid of high-energy accelerators such as the soon to be operational Large Hadron Collider. This talk describes how Lie-algebraic methods are also useful for the design of accelerators.
November 24: Giant Galaxies and Glowing Gas
Prof. Deborah Haarsma and student Luke Leisman
One of the main puzzles of science is determining the origins of the universe--how things formed. In this project, we are studying the most massive objects in the universe, galaxy clusters. Most galaxy clusters have a single huge bright galaxy at the center of the cluster. We were looking for evidence of these Brightest Cluster Galaxies (BCGs) as active cannibals, gobbling other galaxies as the cluster slowly mashes together due to gravity. The space between the galaxies is filled with a vast cloud of hot gas that emits X-ryas. Our goal is to study how the properties of BCGs relate to the properties of the gas and of the cluster as a whole. We completed analysis of 31 BCGs from the REXCESS sample of galaxy clusters, in which we discovered a correlation between the density of stars at the center of the BCG and the density of gas at the center of the X-ray cloud. To test this discovery, we have begun to analyze 240 BCGs in the ACCEPT sample of galaxy clusters; preliminary results from 58 clusters appear to confirm the correlation.
December 1: Fun with classical simulations of double ionization of atoms by near-infrared and visible-wavelength lasers
Students Tim Atallah, Peter Plantinga and Katie Shomsky
We have worked with Prof. Haan doing computer modeling of double ionization. Particular topics have included how the double-ionization process changes with laser intensity and the possibility of electron reattachment at the end of a laser pulse.
December 8: Lipids Kinetics and Sucrose: A Sweet Story
Prof. Paul Harper and student Nathan Meyers
Lipids in water form a variety of structures, including the flat sheet lamellar phase and the rolled cylinder hexagonal phase. Our research focuses on the kinetics of the temperature driven phase transition between the lamellar and the hexagonal phase. Sucrose or table sugar has a variety of uses, including being used as sweetening agent, energy source, and cryoprotectant. When added to lipid-water systems, it has a number of interesting effects. We found that it lowers the temperature of the lamellar-hexagonal phase transition in well-behaved linear fashion, with the change in phase transition temperature being proportional to the sucrose concentration. Surprisingly, we found that the kinetics behave in a strikingly non-linear fashion, a puzzle with which we continue to wrestle.