Seminars are held on Tuesdays, 3:45-4:45pm in SB 101, unless otherwise noted. Meet at 3:30 in SB 157 for refreshments (refreshments are available even on weeks with no seminar!). See Calvin's Visitor Resources for maps and directions to the Science Building.

If you would like to receive regular email announcements for each week's seminar, or have other questions or comments, contact seminar chair David Van Baak.

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

September 17: Physics Scramble
Come early to get your name in the hat and secure a spot on the winning team! With faculty and student names drawn from the hat, we'll move to "scramble stations" in SB176, there to circulate solving brain-teasers and problem-posers. Prof. Jim "the Judge" Jadrich will adjudicate solutions and present prizes.

September 24: View "Physics Film Classics"
We'll view films of J. N. P. Hume and D. G. Ivey, masters of cinematic dead-pan amid the best of demonstration physics.

October 4: The Skies Proclaim the Work of His Hands: What Modern Astronomy is Telling Us about the Attributes of God
Prof. Deborah Haarsma
Astronomical discoveries in recent decades have greatly expanded our understanding of planets, stars, galaxies, and the universe. For people of all worldviews, these discoveries evoke amazement and wonder. How can scientists of different worldviews share the same scientific methods and results, and yet disagree about God's existence and role in the universe? For Christians, who understand science as the study of God's creation, these discoveries illustrate God's beauty, power, faithfulness, creativity, immensity, and love.

 October 8: Discovery of Cosmic Gravitational Lenses
Phil Ammar and Catherine Boersma, juniors, working with Prof. D. Haarsma
According to General Relativity, light which passes near a massive object (like a galaxy) will bend due to the gravitational field. Since 1979, about 60 examples of "gravitational lensing" have been found. Greater numbers of lenses would be helpful in answering several cosmological questions, such as the amount of dark matter and how galaxies change over time. Last March, our group observed a carefully selected sample of 91 radio galaxies at the Very Large Array radio telescope. We analyzed the data over the summer, and are pleased to report the discovery of a handful of new gravitational lenses! Come and hear all about it!

October 15: Summer Research: Two-beam-excited Conical Emission
Michael Scholten, senior, working at the National Institute of Standards and Technology in Gaithersburg, Maryland
By intersecting two beams of same-frequency near-resonant light in a rubidium vapor cell, a circular cone is emitted between the two beams. Degenerate four-wave mixing in the alkali vapor, which is a result of the non-linearity of the medium, causes this effect. Due to energy and momentum conservation, we expect both spatial and temporal correlation of the photons in the emitted cone. In order to determine if correlation exists, we use heterodyne spectroscopy to compare the energy spectra of the cone and the input beam, and use a pair of avalanche photodiodes to detect time correlated photon pairs. Future applications will also be discussed, which include correlated photon pair production for quantum lithography, as well as creating a convenient source for atom optics experiments.

November 15: Inquiry-Based Life Science Curricula
Sara Bennink, senior elementary education major, and Prof. Jim Jadrich
We have developed an inquiry-based, life science curriculum and materials for use in the Grand Rapids Public Schools. These materials have been developed as part of the Howard Hughes Medical Institute grant received by Calvin in spring 2000. This seminar will be relevant for those with a future in science education at any level.

November 19: The Fat's in the Fire: Thermal Behavior of Lipid-Water Structures
Mark Gordon and David Van Norstrand, seniors
Phospholipids are the basic building blocks of cell membranes. In addition to the flat sheet structure found in cell membranes, they often curl up into cylinders at higher temperatures. This structural transition is both physically intriguing and relevant to biology and biochemistry. However, a quantitative understanding of this transition remains elusive and many fundamental measurements have yet to be performed. Over the summer of 2002, we have constructed an automated laser-light scattering apparatus to study this structural transition and have made a number of new measurements. We will discuss how this transition is relevant to biology, the construction of our apparatus, our preliminary results, and plans for future measurements.

November 26: Classical Simulation of 1-D Helium Double Ionization
Clark Cully, senior
It has been observed that when helium gas is excited by a brief laser pulse, within a specific intensity range, a greater-than-expected degree of double ionization occurs. To reduce the complexity of this problem, we used a one-dimensional classical simulation of the helium atom. The principal features under investigation were the "mitten jets", regions of ionization previously explored quantum mechanically. In 2002 summer research, the jets were isolated, enabling their source to be determined.

December 10: The Ideal Electronic Atom
Prof. Roger DeKock, Calvin Chemistry Department
Sequential atomic ionization energies behave roughly as a simple arithmetic progression. An ideal electronic atom will be defined as one for which the ionization energies exactly follow a simple arithmetic progression. The model will be explored by using the effective nuclear charge concepts of Slater and Zener. The relationship of our work to the following will be examined: 1) modern electronic structure calculations, 2) the virial theorem, and 3) screening constants of Gould, et al. published in Physical Review, 1991.