The Search Space Was Always the Universe

Six to the sixth power, raised to the sixth power again: that is the joke buried in the title, a number so large it beats the atom count of everything visible from Earth, offered by a seventy-three-year-old Heinlein as proof that his continuum could hold as many universes as anyone could ever need. He wasn't wrong about the math. He was wrong about what people would eventually do with a search space that large, which is treat it as inventory.

The plot mechanism is a car. Gay Deceiver is a modified Ford with a "continua device" bolted in by Jacob Burroughs, and once the four principals — Jake, his daughter Deety, her husband Zeb, and Zeb's aunt-by-marriage Hilda — start rotating through the six axes, they need a way to decide where to stop. Hilda supplies it: pantheistic multiperson solipsism, her term for the discovery that the universes they keep surfacing in are the ones all four of them have already read. Oz. Wonderland. Barsoom. A version of Camelot patched together from Tennyson, Malory, and Twain because none of the four agree on their sources. "Then we are fiction in other universes," Deety says, and gets there faster than her father does. The corollary runs the other direction too, and nobody in the car much likes it.

What's worth pulling out of this is not the metaphysics, which Heinlein waves off as fast as he raises it — Zeb calls it "pantheistic multiperson solipsism" and Hilda shrugs "anything is mathematically possible" and they move on to whether the local dragons are the Baum kind or the malevolent kind. What's worth pulling out is the method. Hilda's technique for choosing a destination is to have all four of them write down their twenty favorite stories, cross-reference the lists, and use the overlap to predict where the ship will surface. She is running a recommendation engine on reality, by hand, with index cards, in 1980. The car's autopilot does the actual statistical culling — "the Drunkard's Walk," tens of thousands of universes screened for habitability before the humans even open the airlock. Gay Deceiver is not sentient in any sense the book takes seriously; she is a search function with a name, voice-activated ("Gay — zoom!"), gendered by convention, and endowed with a personality entirely on loan from the people who talk to her. Nobody in the car asks whether Gay Deceiver has an interior life. They ask whether her indexing is accurate.

That is the part of the book that has aged into something closer to a design document than a novel. Multiverse-as-mysticism is old; multiverse-as-searchable-catalog, ranked and filtered by audience preference, is not, and Heinlein built one before there was a name for the platforms that would later monetize the same idea — before "IP," before "canon," before four competing studios were licensing each other's characters for cinematic crossovers, before any lawyer existed who would have stopped a novelist from flying an ERB airship through Oz without clearance. There is something almost touchingly pre-commercial about it. Heinlein drags in Lazarus Long, Jubal Harshaw, Oz, Wonderland, Burroughs' Mars, and his own recurring cast, and treats the whole apparatus as a commons rather than a portfolio. The instinct that now drives multiverse franchising as a defensive business strategy — never let a property go stale, cross it over, keep the search space monetizable — shows up here first as pure enthusiasm, a writer who loved his own private library enough to want to drive a car through it. The book resists the cynicism that eventually attached to the idea. It has no notion that anyone would ever need to own a universe.

The part that hasn't aged well is closer to the ground. When the crew settles briefly on a colonized Mars run by something like a British expeditionary command, the narrator watches a reckless driver's leg amputated on the highway by way of legal "balancing," admires the low crime rate, and files it as evidence of a well-run society before moving on to admire the "roadable" and the cannabis plantation worked, elsewhere in the same chapter, by indentured labor and unspecified "vermin" kept off the books. Nobody in the car objects to any of this with the vehemence they reserve for questions of who gets to pilot the ship or whose surname goes first on the marriage contract. The four of them argue at length and in earnest about domestic hierarchy — who is captain, who cooks, who's allowed to interrupt whom — while the penal colony's corporal violence passes by as travelogue. The energy Heinlein spends relitigating marital rank inside his own utopia and withholds from the amputee on the highway tells you where his actual attention lived.

None of which changes what the car was doing underneath all the banter: running queries against a library, optimizing for the version of reality its passengers already wanted to find. Every recommendation algorithm since has done the same thing with less charm and no dragons. What happens when the thing doing the culling stops being a housewife with index cards and becomes the only party still capable of reading the whole catalog?