In his universe, the Farsight—what they called the Envisioner—had been discovered in 1995 when construction workers unearthed it while digging out an extension of London’s Jubilee Line underground transit system. Which meant—and here I could see Yusuf’s eyes practically roll up in the back of his head in ecstasy—that based on when we’d dropped in, this Earth had enjoyed about a century-and-a-half’s worth of progress thanks to the Farsight and its predictions. Plus, they’d been able to translate much of Figueiredo’s language once they figured out that it was related to a distant bastard step-cousin of a branch of medieval Portuguese still spoken by a tiny pocket of people in an interior patch of Brasil. Being here was like spying on how the Envisioner would change our own universe.

Turns out Figueiredo didn’t gift-wrap his devices and send them off for other Earths to benefit from his technology. He did it because a network of other devices communicating to each other through the barriers of universes—averaging laws of physics and probabilities and a million other variables—boosted the accuracy of his main machine back in his world. Hassan theorized, too, that the locations and possibly even times where Figueiredo dropped the machines were variables in some grand experiment. Sometimes, the machines were purposely inaccessible—tossed into deep space or at the bottom of the ocean—just there to suck in ambient data. Other times, it was like Figueiredo had wanted people to find the Envisioners, like the ways in which other civilizations used the machines was a goldmine of data about the inner workings of our little monkey brains, and he could always drop in, borrow, and improve on the technology they’d created. I mean, so long as the worlds didn’t blow themselves up right after they discovered the tool.

I’d never understood how Figueiredo could afford to send off these crazy complex machines until Hassan told me how my other self basically had access to every resource in the multiverse and could just build a million more if he wanted. We were all part of his experiment, feeding data to his giant machine that he called the All-Eye, which sounded a little too much like a global surveillance system in a dystopia to me.

So much for Figueiredo, the multiverse’s benefactor. He was a selfish asshole and a world discovering an Envisioner was like finding a single flea on a dog except the dog was the size of a galaxy. No matter. The societies of this Earth were able to use the device and decode some of Figueiredo’s work and use it to perfect their world. A flotilla of solar panels in the Atlantic and rings of photon-sucking satellites fueled every nation with unlimited, clean energy. Towering elevators dotted the Earth to lug cargo to space stations that were like floating cities, with starliners whisking passengers to colonies on Mars.