Engraved on every body and programmed to repeat, “twitch force” is a muscle’s “measurement of its energy potential,” so the back cover of Michael Redhill’s new volume tells us. Quirky, unaffected and completely at ease with itself, the whole book is a twitchy learning curve. Section headings alone—Astronomical Twilight, Chemical Drowsing, Core Sample—illustrate Redhill’s edgy range of call and response. While reading you inevitably increase your word horde. You find yourself looking up scientific terms for transformations of various kinds. You laugh. You learn.