The 1990 film “The Hunt for Red October” (based on Tom Clancy’s 1984 debut novel of the same name) featured actors like Sean Connery and Alec Baldwin, but the star of the movie for physicists was a revolutionary new magnetohydrodynamic (MHD) marine propulsion system. The so-called “caterpillar drive” worked with no moving parts, allowing a nuclear missile-armed Soviet submarine to approach the U.S. coast undetected. As the submarine captain (played by Connery) said, “Once the world trembled at the sound of our rockets … now they will tremble again—at the sound of our silence.

Popular demonstrations commonly use stretched spandex fabric to illustrate the way in which curved spacetime mimics the force of gravity in general relativity. There are significant potential conceptual pitfalls to such an approach. In particular, it obscures the fact that most of what we ordinarily feel as gravity is due to the warping of time rather than space, a concept that is admittedly harder to demonstrate. Nevertheless, with appropriate caveats simulations of this kind can convey some of the wonder of Einstein’s theory to non-specialists.

Electromagnetic induction is probably one of the most challenging subjects for students in the introductory physics sequence, especially in algebra-based courses. Yet it is at the heart of many of the devices we rely on today. To help students grasp and retain the concept, we have put together a simple and dramatic classroom demonstration that combines sight and sound with a compelling personal story from U.S. history. Other classroom activities dealing with induction have been discussed in this journal,1–4 but we believe that this one will be especially likely to attract and retain student interest, particularly in courses geared toward medical, biological, and other non-physics majors.