Physics for Moderns

Before a beginners' physics class at St. Louis' Washington University, Assistant Professor Edward Lambe plugged in an electric device that shot pennies at a metal disk a few feet away. The pennies scattered off the disk in a significant pattern, but Lambe was not using them to demonstrate the elasticity of metals, Newton's laws of motion, or anything else in classical physics. His penny routine was part of a discussion of what happens when alpha particles (helium nuclei) are shot at heavy atoms such as gold.

First: the Invisible. Most first-year physics courses start as they have started for decades--with levers, gears, and Galileo's falling weights, gradually work their way up to electric currents. As a rule, students are told only as an afterthought about the new science of particles.

But Professor Lambe is one of the growing number of physics teachers who believe that students should take first things first. Since the world of matter is made up of invisible particles, students should start with a study of such particles. His elementary course, which he developed with Co-Lecturer John Fowler, begins with the description of the 16 known basic particles, including such oddities as antineutrinos. But the course is mostly concerned with the commonest particles--electrons, protons and neutrons. As far as possible, classical laws are taught as the gross manifestation of actions and reactions between these invisible particles.

Particles do not, of course, behave like little round balls, so Lambe and Fowler start telling their students at once about the four forces (nuclear, electric, weak interaction and gravitational) that combine to weave the fundamental particles into more familiar kinds of matter. A baseball, for instance, is a very large number of particles held together by nuclear forces (which hold the particles together to form atoms) and electrical forces (which hold the atoms together to form molecules). The earth is an even larger number of particles, held together chiefly by gravitation.

Bugaboos. Very soon Lambe and Fowler are forced to grapple with the bugaboos of modern physics--relativity and quantum mechanics--which are often considered too difficult for students who have not had long training in mathematics. Lambe and Fowler believe that although relativity and quantum mechanics may seem "against common sense," they are really the physical facts of life, and had better be brought in quickly. Relativity is lightly touched on in the third week of the course. The relativistic principle that the mass of a body increases with its speed is used to explain why certain particles, e.g., neutrinos, that have no mass when at rest can exist at all. Quantum mechanics, without which the structure of atoms cannot be really understood, occupies the last third of the course.

Conventional teachers of elementary physics deplore the Lambe-Fowler approach, pointing out that the physics needed in most kinds of engineering is only remotely concerned with relativity or particles. The progressives retort that their students are enlivened by touching the inner realities that make the universe tick.

Behind the new teaching methods is a group sponsored by the National Science Foundation and spark-plugged by Professor Jerrold Zacharias of M.I.T. Says Zacharias: "Relativity and quantum mechanics are essential to understanding our universe. Quantum mechanics is not really modern physics. It is 34 years old, which is twice as old as a 17-year-old freshman. There was a revolution in 1926* and it's high time that we taught it."

* The year in which a burst of work by Heisenberg, Dirac, de Braglie and others firmly established the new science of quantum mechanics.

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