Three Abstracts and a CrackerBarrel

for the 1999 American Association of Physics Teachers Summer Meeting

to be held at at Trinity College in San Antonio, TX, Aug 3-7.

[deep simplicity] [code sciences] [modeling Minkowski] [waves of color]

How can 20th century simplifications benefit introductory classes?
Undergraduate Education Committee CrackerBarrel Session
4 to 5 pm Thursday 5 August 1999 in Cowles Life Science Room 149

Subject: Deep insights of this century, like those of Minkowski, Feynman, and Shannon, are simplifying senior and Edwin Taylor's "second" courses*. Might they impact introductory class teaching as well, and how?


More specifically: (i) Do improvements in approach exist which are both more powerful and algorithmically simpler for students, recognizing that nothing is simpler than "same as last year" for the teacher? For example: Might being specific about a clock's frame of motion be a habit whose time has come? Is insight into "the equation-free psychology of quanta" (via explore all paths) a useful prerequisite for lay as well as professional physicists? Does the statistical approach to thermal physics offer deeper insight for those who will be working with genetic and computer codes, as well as for future physicists? (ii) How have these ideas impacted the way introductory physics is taught so far? For example: What content in the standard intro-physics class reflects 20th century insight? Did the equations of constant proper acceleration in the first edition of SpaceTime Physics catch on with teachers? Did the freshman in Feynman's Intro-Physics course get as much out of it as the physics graduates now enjoying the 3-volume text that materialized as a result? (iii) What factors lessen the receptivity of students, teachers, publishers, and authors to changes in content that might better prepare students for physical insight into the issues of tomorrow? For example: Should we worry if "diversity of approach" (e.g. which arises when a subset of classes but not all use modeling workshop) limits the usefulness of "Cliff Notes" as an alternate way to study? What fraction of students prefer simplicity to intellectual pizzazz, and does Tom Moore's "Six Ideas that Shaped Physics" make progress toward offering both? What fraction of teachers are willing and able to teach in a way NOT that in which they were taught, and will the reception of peer-instruction support or modeling exercises in new texts (as with Sherwood and Chabay, or Serway and Beichner) provide information on the "inertia" we face in this regard? How can a publisher be sure of not alienating a significant fraction of their existing market with content modifications in a new edtion, and in that respect are Jearl Walker's puzzlers in HRW really a clever way to alter not only pedagogy, but content as well? (iv) Is it worthwhile to make sure that content, along with pedagogy, evolves with the times in our teaching of introductory physics? For example: Where else can modern physicists impact the physical insight of a significant fraction of the voting population, and do we want 21st century voters (on issues ranging from supercolliders to global warming) informed in this way? Similarly, do we want computer scientists and molecular biologists of the future to learn about the physical basis of information theory by trial and error, or from us? (vi) How can scientists and authors aware of improved viewpoints stimulate interest, on the part of the popular media as well as on the part of students, teachers, and publishers. For example: Can we find others among us who may in days ahead have the media impact of, for example, a Carl Sagan? Are AAPT meetings helpful in this regard, and what other means might one consider as well?

If as a science enthusiast, student, teacher, researcher, author, or publisher you have thoughts about this subject, please consider stopping in for this roundtable discussion of the pioneers, prospects, pitfalls, and challenges of extending benefits, into the introductory physics classroom, from the 20th Century's deep simplifications.

Postscript: This event was well and diversely attended, resulting in some spirited discussion and new prospects for collaboration in nurturing these developments downstream. Participants included many of the more innovative authors of the community's evolving pool of available textbooks, among them (so far as of Jan 2007) two Oersted Medal winners. Action areas include future contributed/invited paper sessions on content modernization at both AAPT and Physics Education Research meetings, as well as wider involvement in these meetings of standardized test designers for the medical, engineering, computer science, and physics professions. A partly-labeled still from the video (by way of introduction to some of the participants) is below, while unedited streaming videos from the discussion (starting a bit after I opened the session) are now available as well (part 1 and part 2).

Thermal physics, and sciences that involve codes
by P. Fraundorf, Physics and Astronomy, UM-StL, St. Louis MO
Topic Areas: History of the 20th Century, Undergraduate Education
2:15pm Saturday 7 August 1999, Paper Code FD2

Statistical physics before the middle of the 20th Century focussed on the macroscopic behaviors of homogeneous systems near equilibrium, and their microscopic explanations. Then work by information theorists Claude Shannon and Edwin Jaynes clarified the "gambling theory" roots of J. W. Gibbs' statistical mechanics, using the science of inference from partial information. At this point, the tools of statistical physics became eligible for application to communication lines, data compression, population inversions, and most importantly to complex systems far from equilibrium. These include biological heat engines (like photosynthetic plants) that store available work in biomass, and information engines (like video cameras, computers, and researchers) that create correlated subsystems in their environment, often with help from replicable codes (like genes and memes). The job of strengthening students' physical intuition about these systems falls to us, letting us broaden our impact with a subject some said was dead.

For related links, cf. presentation outline, a talk on deep simplification for Ed Jaynes, some web notes on information physics

Modeling motion at any speed, ala Minkowski
by P. Fraundorf, Physics and Astronomy, UM-StL, St. Louis MO
Topic Areas: Modeling Workshop, High School and Undergraduate Education, Computers
6:30 pm Thursday 5 August 1999, Poster Code BK6

Modeling strategies in high school and college physics seem (to me) to formalize a Piaget-like kind of discovery, preparing students for a personal understanding of recognized phenomena, as well as of new phenomena they encounter later in life. Encounters with relativistic motion in a school physics lab are of course difficult to provide. However if we could provide them, and if we alternatively simulate them, a metric-equation based approach to motion at any speed that we owe to Hermann Minkowski will allow students to wrestle on their own with the meaning of the results that ensue. In fact, results from a simple "high speed" air table experiment, using one reference frame but two types of clocks (fixed and traveling), will allow them (if so inclined) to discover both the metric equation, and some definitions for energy and momentum good at any speed.

More specifically, data taken during a high speed air-track experiment reveals how time elapsed on clocks hooked to a glider differs from time elapsed on laboratory clocks, when the glider is first accelerated by a spring, and when it is later allowed to collide with (and stick to) a 2nd glider of similar mass. When students examine measured values for position x and time t between gates in the lab, plus time tau on the glider clock after runs at various energies, the fundamental relations of special relativity will find themselves present in the data, awaiting discovery. For example, students may note that the data fall onto straight lines when one plots: (dt/dtau)2 vs. (dx/dtau)2, energy/mass vs. (dt/dtau), and momentum/mass vs. (dx/dtau). Moreover, the data illustrate in action both Minkowski's flat-space metric equation (including a dx/dt maximum a.k.a. lightspeed of around 1 [ft/ns]) and expressions for kinetic energy and momentum good at any speed. Speeds high enough to show these "frame-dependent time" effects are difficult to achieve with laboratory air-tracks. However, computer simulation of the experiment may be preceeded by a low-speed in-lab modeling exercise, to reinforce the nature of the task.

For related links, cf. A high-speed challenge for modelers, "Do it yourself" kinematics from the metric, Teaching map-based motion

Complex color, and what ray optics left out!
by P. Fraundorf, Physics and Astronomy, UM-StL, St. Louis MO
Topic Areas: Visualization tools for qualitative and quantitative analysis, Computers
6:30 pm Thursday 5 August 1999, Poster Code BK7

Transmission electron microscopes allow one with dark adapted eyes to "drive around" through the stark reciprocal lattice of crystals, using the relatively flat Ewald sphere (of electrons traveling near lightspeed) to map amplitudes in that lattice onto the back focal plane of a magnetic lens. Kevin Cowtan, an X-ray diffractionist at the University of York, in his lament* on the elusiveness of "phase information" in this beautiful but monochrome world, first told us of a way to visualize both the amplitude and phase of a complex number with the intensity and hue, respectively, of a single pixel. This economical trick allows one to visualize, and animate, wavefields quantitatively. We show here examples of visualizations derived thereafter, from ray optics in introductory physics, from electron optics and materials microscopy, and from Feynman propagator views** of quantum weirdness, all heretofore accessible mainly via math.

* Kevin's tale of Fourier duck...
** Edwin Taylor's notes on our "explore all paths" world
For related links, cf. some "reciprocal world" course notes

Abstracts by P. Fraundorf to Previous AAPT Meetings: APS/AAPT 1997, Winter 1998 (3 talks), Summer 1998.

This site is hosted by the Department of Physics and Astronomy (and Center for Molecular Electronics) at UM-StL. MindQuilts site page requests est. around 2000/day hence more than 500,000/year. Requests for a "stat-counter linked subset of pages" since 4/7/2005: .