Physics Confidential

PRINCETON – Each February, I begin the introductory electricity and magnetism course at Princeton University by telling my students that the material we will cover during the semester provides the basis for modern civilization.

Who could quibble with such an innocent statement? Without the discoveries of nineteenth-century physicists and their successors, we could hardly imagine today’s world: no electrical power grid, no televisions, no satellites, no iPads.

Physicists are justly proud of the many ways that their achievements have benefited humankind. But building a light bulb or a telephone doesn’t mean that you understand its basic principles (Thomas Edison and Alexander Bell certainly didn’t). Unfortunately, many of my colleagues – particularly those who write textbooks – present physics as a towering, seamless basilica, ignoring the gaps in our hodge-podge of skewed models. In fact, what is presented as a shimmering cathedral often more closely resembles a hastily erected shantytown.

For example, one needs only first-semester equations to describe reasonably well the behavior of a gyroscope; engineers can then go off and build gyrocompasses that guide aircraft or missiles to their destinations. But if you merely ask, “At what, exactly, is the gyroscope pointed?” you are plunged headlong into one of physics’ deepest questions, one that led Einstein to develop his general theory of relativity – and that, even today, has no definitive answer. I know of no undergraduate textbook that acknowledges the question.