Letters

I loved Richard Muller's discussion of "Physics for Future Presidents" (P&S July 2010), agreeing heartily with his overall message and most of the details. I've read his book and found it accurate and well written.

In physics courses for non-scientists we do indeed assume too often that students can't learn "real physics." As Muller says, many of these students thirst after the kind of scientific knowledge that is valuable to them, but instead we talk down to them, we hide behind the fog of math, we try to make them into mini-physicists. Math is not the essence of physics; concepts are.

The notion of teaching concepts instead of technicalities to non-scientists has been widespread since at least Paul Hewitt's first edition of Conceptual Physics in 1971. In fact Albert Einstein and Leopold Infeld's wonderful book for the general public, The Evolution of Physics: from early concepts to relativity and quanta (Simon & Schuster, Inc., New York, 1938), takes a purely conceptual approach. But many instructors still insist on an algebraic approach. How many generations of non-scientists will we alienate before we learn? But then, it's not really important, right? These students--our future attorneys, school teachers, parents, reporters, political scientists, policy experts, legislators, and presidents--are mere non-scientists, right? Yeh, sure.

I'm delighted that potential physics majors at Berkeley are urged to take Muller's course before beginning physics. Every physics student should in fact begin their education with an entirely conceptual introduction to a broad spectrum of classical physics and especially modern physics, along with physics-related social topics.

Muller's "ultimate goal …to have both elected and electorate be scientifically literate" is absolutely crucial in today's science-dominated society. Science-and-society topics should be included in every introductory physics course for non-scientists and also for scientists. Industrialized democracy demands a citizenry that's literate in such topics as energy resources, global warming, nuclear weapons, and technological risk.

I do disagree with Muller's opinion that it's hopeless to teach the concept of conservation of energy because "it takes over a year before even math-adept students begin to understand this subtle concept." Lately it's become fashionable to try to teach energy without ever defining the term, and I suspect that this lies behind Muller's pedagogical difficulties. But energy is traditionally defined as "the ability to do work," and there's no good reason to avoid this clear, concise, teachable definition. Work is done when a force acts through a distance. The amount done, assuming the force is in the direction of the displacement (other directions can be neglected in a conceptual course), is force times distance. The amount of work a system can do (relative to some "zero energy state") is then its energy, be it kinetic, gravitational, elastic, thermal, electromagnetic, radiant, chemical, nuclear, or some other form [1]. For example, a system's gravitational energy is the amount of work it can perform due to the gravitational forces acting on it. A system's "energy" is the total amount of work it can do. Energy is the most useful physics concept. Students deserve a clear definition of it and a clear statement of its principles [2].

My other disagreement is Muller's advice to refrain from explicitly teaching the "scientific method." The scientific process is the central lesson for non-scientists and, indeed, for scientists. Science is based on evidence and reason, not on charismatic sages, old books, kingly power, religion, emotion, or your daddy's opinion. Indeed, the American Association for the Advancement of Science's book Project 2061: Science for All Americans (AAAS, Washington, DC, 1989) devotes its lead chapter to "The Nature of Science," and emphasizes that this topic is essential for scientific literacy. The perils of pseudoscientific nonsense and religious fanaticism evident all around us testify to the importance of understanding and using, particularly in matters of public policy, the scientific process: knowledge comes from evidence and reason [3].

Despite my quibbles, Muller has introduced a valuable new approach to teaching scientific literacy.

[1] Art Hobson, "Energy flow diagrams for teaching physics concepts," The Physics Teacher 42, pp. 113-117 (Feb 2004). Also see Art Hobson, "Energy and work," The Physics Teacher 42, p. 260 (May 2004) and references therein.
[2] Art Hobson, Physics: Concepts & Connections (Pearson/Addison-Wesley, San Francisco, 5th edition 2010), Chapter 6.
[3] Ref. 2, Chapter 1 "The way of science: experience and reason," and brief "How Do We Know?" sub-sections in every chapter.

Art Hobson
Professor Emeritus of Physics
University of Arkansas, Fayetteville

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These contributions have not been peer-refereed. They represent solely the view(s) of the author(s) and not necessarily the view of APS.