Rita slumped into the patient’s chair in the doctor’s office as Jenn bounded away in the direction of the coffee robot by the nurses’ station. She yawned, scratched halfheartedly at the inflatable cuff around her arm, and tried not to doze off. The doctor returned regrettably rapidly, just as the blood pressure monitor ground its gears and the cuff began to inflate again, sending sparks of pain into her arm. “So!” Dr. Jenn bounced into her chair. “World-walking! Let’s skip the physics for now, it goes off into brane theory, which nobody understands without a PhD in pure mathematics. Let’s just say we live in a multiverse—a bundle of parallel universes branching off each other. The vast majority are identical but for some quantum uncertainty, and they keep merging and reemerging. But there are sheaves of parallels where the differences add up to something we can tell apart. A huge number of such sheaves exist, and we call them time lines.
“The world-walking mechanism uses some intracellular machinery, self-replicating wet-phase nanotechnology with embedded quantum dots to ensure coherence of the wave function, that can bounce you—and anything electrostatically earthed with you—into another time line, as long as the Q-machines are all triggered together. The trigger event is a bunch of them going into the same state transition more or less simultaneously, and the easiest way to get this to happen is by hitting a bunch of neurons in your brain that contain Q-machines with a signal that excites all of them at once. The easiest bunch to trigger are in your lateral occipital complex, where your vision system recognizes images. We hit them with a unique image—a complex knotwork—and as you recognize it the Q-machines in that part of your brain activate.
“You’re probably wondering how we control which time line you end up in. It’s all in the knot we use. Different knots have different dimensional parameters and so they trigger different recognition groups, and this causes differential ensemble excitation in the Q-network—”
Rita raised a hand. “Whoa. This is too much.” She smiled defensively. “I look at a knot, and it makes these Q-machines send me to another universe?”
Dr. Jenn smiled back at her. Patronizingly or sympathetically, it was equally annoying. “That’s the gist of it! My, you’re quick on the uptake this morning. Yes, but not all knots work in this way—only ones that follow certain geometric rules. And of course they don’t take you anywhere yet because your Q-machines are inactive because of the missing link between your own central nervous system and the Q-machines.” Rita’s heart sank as she noticed Dr. Jenn gearing up for more neurobabble: “The world-walkers all carry a gene for a nonstandard postsynaptic glutamate receptor. It binds to the Q-machines and activates them. However, whoever designed the mechanism used a hack to switch production of the modified receptor on, and it turns out to be a recessive trait. You’ve got the gene for the receptor, but it’s not expressed—actually making receptor proteins—unless both your parents were world-walkers, which in your case they were not.”
Dr. Jenn paused barely long enough to draw breath. “We can fix that now, thanks to a big-budget top-secret research project called JAUNT BLUE. You’ve heard of the Six Million Dollar Man, or the Seven Million Dollar Woman? You’re going to be the Half Billion Dollar World-Walker. That’s inflation for you…”
“How exactly does this work?” Rita narrowed her eyes, annoyed by Dr. Lane’s attempt at manipulating her through levity. “Genetic engineering? Stem cells?”
“No. That would be impractical and potentially dangerous. Instead, we do some tests to make sure that your receptor complex is inactive because of the stalled repressor function, then infuse a short interfering RNA sequence into your cerebrospinal fluid that gives it a kick. The only dangerous aspect is that if you start world-walking prematurely—if something triggers you—you can end up lost in para-time. Which is why you’re sleeping in an underground bedroom where the only place you can go is a corresponding underground mirror room on a base in time line four.”
“What? You mean I can end up buried underground or something?”
“No.” Dr. Jenn shook her head emphatically. “You can’t world-walk into a solid object. Nor can you move while world-walking. Actually, there’s a lot about it that we don’t understand yet: the Earth is moving through space, for example, so why do you move with it? What about the air in the time line you’re going to, that you displace? We figure there are safety mechanisms we haven’t decoded yet … but that’s not my department: that’s for the physicists to worry about.”
“Oh.” Rita thought for a bit. “So what happens is entirely controlled by my, my seeing some kind of, what did you call it—a trigger engram? A knot?”
“Yes. Whoever designed the world-walking Q-machinery was pretty careful about that. They picked a set of topological deformations in the visual field that don’t occur in nature. And, believe me, this mechanism was designed: it certainly didn’t evolve. It’s very unbiologically straightforward. While they recycled the glutamate pathway and the recognizer networks from existing neural wetware, the self-replicating Q-dot machines have all but got patent numbers stenciled on them. They look a bit like mitochondria under an electron microscope, and they’re self-replicating, like mitochondria, but they’re a hundred percent engineered and there are additional mechanisms to ensure they get copied and packed in the acrosome during meiosis. It’s high-grade nanotechnology, miles ahead of anything we can match yet. Anyway, you’re mostly safe from running into a trigger engram by accident. But … you’ve flown recently? You saw the DHS notice when you signed onto the in-flight wi-fi? They only switch on the wi-fi above ten thousand feet, once the plane is airborne, and the animated background to the DHS logo—”
Rita swallowed. “It’s some kind of knotwork design. Is that a trigger engram?”
“Yes. The theory is that if the Clan are sending world-walkers here and they try to catch a commercial flight, the plane will land with one fewer passenger than it took off with, which will flag it for us. The flight data recorders log the flight’s GPS coordinates when the wi-fi is switched on, so we know where to look for the world-walker’s body.”
“But I—”
“Relax. There are a couple of ways of turning off your sensitivity to triggers. The simplest method is to close your eyes. If you need to switch off for longer, there are drugs that mess with your glutamate pathways and render you unable to world-walk for a period of hours to days. And we think there’s a kind of meditation you can practice that will stop it from working on you, if you have time to put yourself in the right frame of mind.”
“Where did you get that from?”
Jenn’s smile slipped. “I can’t tell you that.”
“DHS has captured world-walkers. Right?”
Dr. Lane’s smile turned cold. “You are not supposed to ask that kind of question. If DHS has captured world-walkers, it would be a very serious and highly classified project. Even asking about them without prior clearance would be a serious security infraction. Luckily for you I don’t know the answer to your question so I’m going to assume that the answer is no, so your question is not actually a security infraction. But how about we agree that we didn’t have this part of the conversation at all? It’ll make life ever so much easier.”