Seminar: Fall 2005

Seminars are held on Tuesdays, 3:45-4:45pm in SB-110, unless otherwise noted. Meet at 3:30 in SB-157 for refreshments (refreshments are available even on Tuesdays with no seminar!). See Calvin's Visitor Resources for maps and directions to the Science Building.

Schedules from previous semesters: Spring 2005, Fall 2004, Spring 2004, Fall 2003, Spring 2003, Fall 2002, Spring 2002, Fall 2001, Spring 2001, Fall 2000, Spring 2000, Fall 1999.

September 20 (part 1): Hunting for Distant Galaxy Clusters.
       Andrew Butler and Prof. Deborah Haarsma, Calvin College.
  Galaxy clusters are the single most important class of objects for understanding the universe as a whole. Their gravitational interactions at high redshifts can be used to calculate the mass of the dark matter in between the cluster galaxies and around each galaxy. In turn, this gives critical cosmological parameters, especially Ωm, more accuracy. In addition, by examining clusters, the evolution of individual galaxies can be better modeled. Thus, if galaxy clusters are sampled over a sufficient expanse of time and enough are found, they can show just how the current observable universe came to be how it is now. Even though a substantial number of clusters have been discovered relatively nearby (redshift < 1), not many clusters have been identified at redshifts of around 1-1.3, when the universe was about 30% its current age. In this seminar, we present results of the analysis of nine galaxy cluster candidates that were chosen based on sources of diffuse X-ray emission (from the intracluster gas). Our data was taken with Kitt Peak’s 4-m telescope and the FLAMINGOS infrared detector. We used a powerful technique, called the red sequence method, to identify the clusters in our images. According to preliminary results, we think that at least one of these candidates is a definite cluster.

September 20 (part 2): Three-Dimensional Classical Ensemble Studies of Electron Momenta in Non-Sequential Double Ionization.
       Armin Karim and Prof. Stan Haan, Calvin College.
   The goal of our research is to explain how a high-intensity laser can strip both electrons from a helium atom. Numerous experiments have shown that the amount of double ionization is up to a million times greater than would be expected if the electrons behaved independently from each other. Theoretical work has indicated that the most likely mechanism is “recollision,” a process in which one electron escapes but then is pushed by the external laser field so as to return to the core area and share energy with the inner electron. Our research supports the use of a completely classical model for this mechanism. We use a computer to propagate 400,000 model atoms through a 10-cycle intense laser pulse. We analyze the final positions and momenta of the electron trajectories and compare with experimental results. Our procedure qualitatively reproduces many important experimental results. In this presentation, we focus on our analysis of the final momenta of the doubly-ionizing trajectories in our ensemble and explain how our results correlate with experimental findings..

September 23: Cassini Mission to Saturn: Spacecraft Engineering and Scientific Discoveries.
       Professor Matt Huen (Engineering) and Professor Larry Molnar (Physics and Astronomy), Calvin College.
       NASA's Cassini mission to Saturn has returned some of the most exciting science from any interplanetary mission to date. New information about the rings and moons has revolutionized our understanding of the Saturnian system and will provide data for scientific investigations for years to come. Prior to Cassini's arrival at Saturn, many technical hurdles were overcome and engineering solutions were necessary for a successful mission. This seminar will describe the design of the Cassini spacecraft and the Huygens probe, discuss the engineering challenges and successes of the mission, and describe the scientific discoveries made by the mission.

September 29 (Thursday, 7:30 p.m. in SB-010): Einstein and his World.
       Martin Klein, Eugene Higgins Professor Emeritus of Physics and History of Science, Yale University.

September 30 (Friday): New Paths to the Depths of Physics: Einstein in 1905.
       Martin Klein, Eugene Higgins Professor Emeritus of Physics and History of Science, Yale University.

October 4 (part 1): Pre-emptive Research: Choose to study asteroids in the mainbelt before we have to study them three seconds away
       Kathy Hoogeboom and Professor Larry Molnar, Calvin College.
   The study of asteroids is important for learning about the history of the solar system, and somewhat about the future as well, especially regarding the possibility of catastrophic collisions with Earth. Observing the characteristics of the present asteroid population and its dynamics allows extrapolation backwards and forwards and constrains models attempting to describe the history and evolution of our solar system. We focused along two major lines of research: resonances that are apparent in the dynamics of the asteroid belt, and the size distributions of areas of the mainbelt and various asteroid families. As a result, an unexplained resonance was found as well as significant variation in the size distributions over the whole asteroid belt. We speculate that these findings may have important theoretical implications regarding formation history and orbital evolution.

October 4 (part 2): Serendipitous Discovery of an Eclipsing Binary Star System
       John Vander Heide, Calvin College.
   Using the Calvin-Rehoboth observatory in the pursuit of another subject
altogether, we have discovered a binary star system so tuned to our line of
sight that the stars fully eclipse one another every 2.15 days. We will show
how one can determine the basic properties of the stars by analysis of the
light variation. Furthermore, one or both stars turn out to be strong X-ray
emitters. We will describe what spacecraft observations are being planned to
follow up on this rare opportunity.

October 18: Einstein's Special Theory of Relativity for Beginners
       Professor Stan Haan, Calvin College.
   This talk is the next installment in a series of presentations celebrating the 100-year anniversary of Albert Einstein's breakthrough year of 1905. One of his brekthroughs was Special Relativity, which challenged our understanding of space and time. This talk, most of which will be accessible to people with no prior background in relativity, will review the basic ideas and implications of the theory. Topics to be covered include time dilation (time passes at different rates for different observers), Lorentz contraction (moving objects are shortened in their directions of motion), the relativity of simultaneity (events that are simultaneous for one observer need not be to another), and the distinction between what we "see" and what we "observe." Come and have your understanding of space and time challenged!

October 21 (Friday, 12:30-3:30 p.m. in DeVries Hall Atrium): Science Division Student Research Fair
       Calvin student presenters, including several from Physics & Astronomy.
  During the summer of 2005, the Science Division had a total of about 50 students involved in research. You are invited to see and hear about this research at the annual Science Division Student Research Fair. Many of the students will be presenting posters explaining their work. Refreshments will be available. The posters will be on display until November 4.

November 1: Exploring Phase Transitions in Lipid-Water Systems via Laser Light Scattering and Capacitance
       Peter Cook and Alexis Reynolds, Calvin College.
  Lipids are biologically important molecules that form into various phases when in water. This summer we continued researching the kinetics of their phase transitions. Significant portions of this summer's research were spent searching for discrepancies between our experimental results and other published results in order to verify our laser light scattering method. Also we started developing a completely different method of studying lipid kinetics by measuring their electrical
properties.

November 15: Neutrinos in the left-right model . . . and a bit of chaos.
       Prof. Ken Kiers, Physics Department, Taylor University.
  In the first part of the talk I review some of the history and current status of neutrino physics. Large strides have been made in the past decade in the experimental understanding of neutrino masses and mixings, yet the incredible smallness of the neutrinos' masses remains a theoretical puzzle. Theorists have long postulated that the solution to this puzzle could provide valuable clues to the structure of physics at very high energy scales (and short distance scales). The left-right model of particle physics provides an intriguing solution to the puzzle through the so-called “seesaw mechanism.” This part of the talk describes a recent theoretical investigation of the neutrino sector of the left-right model.
   The second part of the talk describes recent work on the chaotic dynamics of a particular electronic circuit. The circuit in question is straightforward to understand and to build, and makes an ideal project for advanced undergraduate students. Furthermore, the dynamics of the circuit can be modeled very accurately, allowing for excellent comparisons between theory and experiment. Faculty and students at Taylor University have developed the circuit into a commercial undergraduate laboratory product.

November 29: Exotic Molecules and Isotope Studies in Atom Traps
       Kristin Datema and Prof. Matt Walhout, Calvin College.
  Atom-trapping experiments have provided the basis for recent advances
in radio-isotope dating and molecular spectroscopy. This talk will
briefly summarize these advances and describe related work that is
ongoing at Calvin.