For a while he wasn’t convinced that the Envisioner worked in the way Kaori said it did, or that it was even evidence of an alternate universe. The machine was a souped-up modeling device at best. Probably some big hoax. He changed his tune pretty quickly once he was sitting in the living room of his alternate self, having a glass of wine and talking shop.

I asked Yusuf how he thought time worked, especially with this whole multiverse thing kicking around. How it messed with my head that some parts of Figueiredo’s world seemed so far ahead of ours—obviously the Envisioner and whatever powered it—and some seemed behind us. The greenish, domed screens on the machine and elsewhere in Figueiredo’s lab, the glowing buttons and dials where we had touchscreens.

Yusuf had a rare afternoon off, back before he was co-running the Compound with Kaori. I’d flopped onto his bed and was half-asleep as he traced squiggles on my lower back over my T-shirt.

“I think the better question is what kind of multiverse exists,” he said.

We could live in an eternally inflating multiverse where universes shimmer to life because of random fluctuations. Like an infinite ocean, with each universe a bubble that pops up for a comparatively short speck of time. Or in one infinitely large universe with islands of matter—each basically a separate universe—separated by huge distances we could never dream of crossing. Or a multiverse that’s constantly branching with new universes for every possible outcome of every possible event down to the quantum level, with each universe a slightly different film?

I appreciated his dumbed-down similes. More so, the way my skin was singing under his fingertip.

“See, now it just sounds like you’re making this stuff up as you go along,” I said.

He traced another little bubble over the cotton on my back for a new universe that had just popped up.

“Who knows if in another universe you’re the one explaining this to me,” he’d said.

“I bet.”

Figueiredo had tossed the Envisioners into universes that had been in different stages of their life cycles. He’d sent some to universes that could support life, others to Earths crawling with people, others where the forces of nature squashed the machines as soon as they appeared. I pictured the machines dropping out of the skies over cities. Ancient crocodiles swimming around an Envisioner in a murky, primordial ocean.

But then again, we live in a model-dependent reality, which is that our brains use sensory observations to create a model of our environment. Thinking about concepts of infinite time and space could be one big, non-helpful headache, Yusuf had told me. The branches are all tangled up, the scenes of us spliced together into a movie trailer supercut.