Computers in Physics

Computers in Physics Nothing Going Nowhere Fast: Computer Graphics in Physics Courses William G. Harter Citation: Computers in Physics 5, 466 (1991); doi: 10.1063/1.4823013 View online: http://dx.doi.org/10.1063/1.4823013 View Table of Contents: http://scitation.aip.org/content/aip/journal/cip/5/5?ver=pdfcov Published by the AIP Publishing Articles you may be interested in A project-oriented course in computational physics: Algorithms, parallel computing, and graphics Am. J. Phys. 76, 314 (2008); 10.1119/1.2839093 A First Course in Computational Physics Am. J. Phys. 63, 283 (1995); 10.1119/1.1807233 A First Course in Computational Physics Am. J. Phys. 62, 861 (1994); 10.1119/1.17476 A First Course in Computational Physics Phys. Today 47, 63 (1994); 10.1063/1.2808610 Computer projects in physics: A course Am. J. Phys. 49, 791 (1981); 10.1119/1.12680

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Nothing Going Nowhere Fast: Computer Graphics in Physics Courses William G. Harter

computer simulations can achieve what physics textbooks sometimes fail to do: make learning and teaching more exciting f you hear someone say that a new computer will save you time and make your job easier, it is probably a salesman talking. Anyone who has programmed or managed a computer system knows that you usually end up spending more time and effort than if you had just done the old job by hand. As a general rule, you should only use a computer if you enjoy it and if you are trying to do a new job that would be impossible without the machine. . This rule applies especiallyto the use of computers in physics instruction. Converting a standard university sophomore physics book to the electronic medium would be extremely difficult to do, and all you would have at the end is a mediocre text that flickered. We thought that as long as William G. Harter is a Professor of Physics at the University of Arkansas, Fayetteville, AR 72701. Harter's physics courseware grew out of his research on computer graphical methods to analyze atomic and molecular symmetry and spectra and animation techniques to understand chaotic dynamics. He is co-inventor of the Harter Heighway fractal dragons. His symmetry analysis and computer animation methods helped in the recent discovery ofC6Q (Buckminsterfullerene), a molecular cage with the icosahedral structure of a soccerball.

we were going to all this trouble we should take full advantage of the medium, and start over by teaching in a way that is only possible with computer technology. Some early experiments with such a radical "throw out the book" approach to physics teaching, are being tried at the University of Arkansas. For each topic, we are creating entirely new text and program "modules", which are presented in lecture form using projectors, and used by students in a study-lab. Each module focuses on a particular topic, which is some phenomenon, experiment or physical process. It could also be a mathematical process such as integration or matrix diagonalization. Each module is designed to expose the mathematical and physical theory relevant to the topic, using computer-simulated "thought experiments" and animated mathematical representations of phenomena. In this manner we hope to create a more natural approach to mathematics and physics, that is more like the way in which these subjects were originally conceived. At first sight, it might appear that we are trying to show something

using nothing, or that we are replacing real physics with cartoons. Bigscreen computer simulations are definitely not the "real thing", but they do have certain advantages. The simulations can be slowed down, idealized, repeated, dissected and displayed, in ways that no real demonstration would allow. Also, simulation in a general sense is really the heart of physics. Our best theories are really nothing but models. The computer provides a better way to play with more models. We felt that the sooner students can participate, the better it will be for them. We find that a good simulation (combined, if possible with a real experiment) can catch a student's attention and make learning and teaching more exciting. At first, students are much freer with questions like: "Why is that thing wiggling?" than questions about methodology, like: "Why did you add 16e?" We find it is much easier to introduce the mathematical part of the theory by starting with some clear moving pictures of the physical phenomena. It helps the students if the pictures can be used to test and motivate the theory at each step, and experimen-

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tally verify it quickly. Success of this approach depends critically on the choice of phenomena for each module, and how each one is programmed, displayed and presented. Herein lies the art of this approach, and a potential flaw. Computer technology is improving rapidly, but this does not guarantee that computers will make good educational tools, any more than improved printing technology guarantees good textbooks. A lot of good physics, pedagogical writing and skillful computer programming has to be done in concert. Hence, this has to be a long-term project, involving many diverse contributions. Also, it has to be a modular or topical approach, so that the transition can be made gradually. At first, a professor might experiment with one or two modules, but continue to teach most topics as before. Later, as modules increase in number and quality, they can be welded into an entire course and laboratory. One of the goals is the integration oflecture with laboratory, and theory with experiment-something we have failed at miserably so far. Already, we find that the topical or experimental approach, aided by computer graphics, complements and improves the conventional methodological or theoretical approach to teaching. The topical approach is like the case study approach used in business schools, where theory is taken less seriously and real experiments are dealt with immediately. For one thing, this approach provides a way out of the "tyranny ofprerequisites", which goes something like. . . "This theory is really boring, but we need it to understand next year's (boring) material." It is probably better to learn theory by repeating interesting experiments, as a researcher would do, instead of the other way around. Computer simulations make this topical approach more practical. Some excerpts from examples of modules are described below, to show how this approach does things that conventional textual approaches have not done. One of the first modules is called Bounce!t. It is based on a spectacular superball experiment, and introduces the concepts of momentum, force and energy. The "real" experiment involves a super-

Fig. 1: (a) Ball ml rebounds toward m2 with '1'1 = 1.0. A head-on collision is about to happen.

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physics code. (Is it any wonder that academic software development is slow to catch on?) The situation is improving. A number of new tools have recently

names of procedures alone occupies a whole page (see Fig. 25) . Dozens of these loops are needed in each program, such as Relativlt, and that is not counting a single line of actual

Fig. 20: Butler on space-time path between Happenings 1 and 2 (Lighthouse view).

come out which may help. These include new graphical programming systems, such as ProGraph. 8 The idea is to build programs and interface structures at ever higher levels, using

Fig. 21: Butler(s) on space-time path between Happenings 1 and 2 (Ship view).

Happening 2: Creation of Butler and 'Anti -Butler'

Happening 1:Annhilation of Butler and 'Anti-Butler'

Fig. 22: Space-time switchback path traced by butler(s) (Ship view).

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Fig. 23: Space-time switchback paths of galloping waves seen from moving frame. Reuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions. Download to IP: 223.252.36.41 On: Wed, 21 Sep 2016 16:15:34 476 COMPUTERS IN PHYSICS, SEP/OCT 1991

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screen representations of the objects, structures, and flow diagrams. They cost about three times as much as the development systems we have been using. However, they could be well worth the price for courseware development. When one gets an idea for a new module, or for an improvement to an old one, it should not mean weeks or months of programming nightmares. It is interesting that the laboratory experimentalists have had graphi-

cal block design programs, such as Lab View, 9 almost from the beginning. However, full Lab View setup costs thousands of dollars and is not really designed for most classroom or theoretical programming tasks. At the other extreme are user-oriented general purpose mathematical programs, such as Theorist 10 and Mathematica. I t These are excellent research tools, but are not designed for lecture demonstrations. We have used these programs in the classroom, but the

instructor has to spend a good part of the time typing away off in the corner like the Wizard of Oz. It is difficult to teach a class and input complicated commands at the same time. Good lecture demonstration software needs to have a tailor-made interface for instructor and student and avoid keyboard use as much as possible. In any case, the electronic simulation and illusions are bound to take their place beside chalk, overhead projector and VCR images, as a way

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