HOW TO INVENT EVERYTHING

You’ve got a time machine. Now what? This good-natured, sharp user’s manual has plenty of solid suggestions for building a world that works.

"The FC3000 is the most reliable time machine on the rental market today,” coos the narrator—in robotic voice, one assumes—of North’s (Romeo and/or Juliet: A Chooseable-Path Adventure, 2016, etc.) latest, apparently geared to teenagers but at times a challenge for even the tech-savviest of grown-up nerds. That voice ought to remind you of HAL in 2001, since the time machine rebels, or at least refuses to function, leaving the traveler stranded in some ugly time of history needing a quick technological fix. Let’s say, for instance, that you land in a world innocent of charcoal, “the most useful substance you can make out of some wood and a hole in the ground.” Now, why would charcoal be an improvement for humankind? Because, among other things, it renders water safe to drink. North goes on to explain the whys and wherefores of oxygen, the terrestrial atmosphere, the science of dry distillation, and other wonkiness before getting into the actual making of charcoal, by which time readers will have attained the sense that it was a momentous invention when charcoal occurred to someone all those years ago. Just so with watermills and windmills, the printing press, logic gates, and other hallmarks of civilization, some of them the kinds of things you didn’t know you needed until after the fact and indispensable thereafter. North’s book isn’t quite as information-rich—or as apocalyptic—as Lewis Dartnell’s The Knowledge (2014), but it’s a kindred spirit, packed with cool, fun, and useful stuff such as the makings of a rehydration drink rich in electrolytes, "which is of course just the sciency-sounding way to say there’s salt in it.”

A friendly and thought-provoking reference, just the thing for the bright kid in the family, to say nothing of the neighborhood time traveler.