STEPHEN HAWKING'S SNAPSHOTS OF THE UNIVERSE

A moderately challenging survey of selected physical principles and astronomical phenomena, conveyed through “experiments” that are actually ingeniously designed interactive games and demonstrations.

Title notwithstanding, Hawking’s direct contributions are limited to a few voice-overs in embedded short videos—including one funny clip in which he sits beneath a tree lecturing about gravity as virtual apples fall all around. The general content covers eight topics addressed in his popular works (purchasable here through multiple links), including the physics of orbits, relativity, bent space and, of course, black holes. Each topic, opened by one of a row of icons on a bottom ribbon, features a general statement of principles, expanded explanations behind a “Why?” button, and an activity. In “Building a Solar System,” readers can launch planets into orbit but must aim carefully to prevent catastrophic collisions. The graphics all respond briskly to tapping, touching or tilting, and most of the activities escalate in difficulty, video-game style. Though there is no audio narration except in the inset featurettes, the app features a full slate of electronic sound effects, as well as background music. Along with a clear picture of how our understanding of the universe has evolved from Democritus’ atoms to string theory, readers will come away with a firmer handle on some of the basics of physical mechanics both celestial and earthly.

An able presentation, much enhanced by high-quality digital content.