Zeitgeber

by Greg Egan

  A sidebar offered links to academic sources on sleep disorders. Sam followed the one on “free-running sleep” to a review article in a medical journal. The vast majority of cases where people’s body clocks ceased to be entrained by the outside world involved total blindness, where the patient had lost, not just vision itself, but the retinal ganglion cells that were sensitive to ambient brightness. Sighted people with the disorder were supposedly rare, and often had tumors, head injuries, or other detectable causes of damage to the suprachiasmatic nucleus that orchestrated the circadian rhythm. In one study, they’d also been found to have significantly longer cycles than normal—unlike the people on the forum.

  He heard Laura approaching. “What are you looking at?” she asked.

  Sam described what he’d read so far, trying to downplay the pessimistic conclusion. “I’m sure there’s a selection effect here,” he said. “Anyone with a problem that went away quickly probably wouldn’t post on a site like this.”

  But Laura seemed intent on preparing for the worst. “If Emma’s a free-running sleeper now, how often will she fit in with a normal school day? To really be able to concentrate, she’d have to be awake by seven, but not up so early that she’s falling asleep before five. That’s a three-hour window to wake in, between four a.m. and seven a.m.—one-eighth of the clock. So for a five-week block in every forty she’ll be fine, but for the rest…”

  Sam said, “If it really does come to that, I could always home-school her. But it’s only been a fortnight! Maybe she’ll just keep waking later and later until she gets back to normal—and then she’ll be so happy that she’ll slam on the brakes, and that will be the end of it.”

  4

  Sam arrived for the first class of the new term feeling sharp-witted and thoroughly prepared. The day had started as well as he could have hoped: he’d woken at five, found Emma still asleep, then spent the hour until she rose reviewing his lesson plans. But each time he turned away from the blackboard to gauge how well his line of exposition was getting through, his gaze was drawn to the empty chairs in front of him, and he lost his thread completely.

  A third of the class was missing. A cynical part of him was tempted to attribute this to copycat malingerers, but that couldn’t be the whole story: two of his most enthusiastic students had failed to show up. When he asked a question, he still found himself reflexively preparing to deflect their responses to give someone else a chance to answer, and the silence that greeted him instead was unsettling. No one had died, or was even ill in any normal sense, but the thinning numbers still felt like the sign of some terrible loss.

  At lunchtime, the staffroom was less starkly depleted, but everyone in sight looked anxious. Sam joined one dispirited group.

  “We need to start doing something more,” he said. “Sending students worksheets and hoping they’ll pick up what they miss from YouTube lectures at three in the morning isn’t going to cut it.”

  “So are you volunteering to come in at three a.m.?” Gloria asked. “And if you are, who’s going to teach your regular classes?”

  Sam said, “The overall numbers aren’t changing; there are exactly as many teachers per student across the district as before. We just need to reorganize things, matching up students and teachers by phase. I’m not free-running myself, but I’d be happiest following my daughter’s phase. If she could go to school when it suited her, I could work those hours, teaching any students in the area who were on the same schedule. My old classes would have to be merged with those from the closest two or three other schools—”

  Sadiq cut him off. “That’s not going to work. The logistics for keeping the buildings open twenty-four hours a day would be unmanageable, let alone shuttling kids across three suburbs in the middle of the night. If students can’t make it in normal hours, we need to be flexible, but not like that. We need to use software, video lectures, whatever it takes to keep them up to speed. But they’ll have to do it from home.”

  Tom regarded them both as if they’d lost their minds. “Whatever’s causing this,” he said, “it’s not going to last forever. In a couple of months, we’ll be back to normal.”

  “You think it’s going to burn itself out, like a bad flu season?” Sam replied. “The way it’s spreading doesn’t look like an infection. Nor does the biology: there’s no inflammation, no antibodies.”

  Tom snickered. “Yeah, well, if ninety percent of it’s ‘viral’ in a different sense, what would you expect?”

  “Hardly ninety percent,” Sam retorted. “And even if you think that many kids don’t want to be here, most adults have nothing to gain by faking it; they don’t have enough paid sick leave or income protection insurance that they can lie in bed all day—and all it would take to prove that they’re frauds is one polysomnogram.”

  Tom was unrepentant. “People manage to do shift work all the time. If a nurse can turn up for a graveyard shift, no one has any excuse not to show up when they’re needed.”

  Sam was growing angry now. “Some people adapt better to shift work than others—but if they do, it’s because their circadian clock is responding to all the timing cues: they’re out of bed, moving around, eating, exposed to bright light. The whole problem for free-runners is that none of those cues affect them! It’s no different from being blind to sunlight—except you’re also blind to temperature, food, exercise, social interaction, and every jet lag pill ever invented.”

  Tom didn’t reply, but he adopted the pained expression of a martyr badgered into silence. He knew the truth: anyone with a spine would grit their teeth and rise from their bed to meet their obligations.

  When Sam picked up Emma, he watched the elaborate ritual of her parting from her best friend, Natalie. After the hug that was meant to finalize things and let them go their separate ways, they turned back to each other no less than five times, with afterthoughts and reminders.

  “How was school?” he asked, as she approached.

  She shrugged. Sam didn’t press her; he had no need to quiz her to see that she was perfectly alert. When she’d first resumed normal attendance, she’d spent half an hour telling him how happy it made her, but by now she was probably just taking it for granted. He hadn’t had the heart to warn her that the situation might not last.

  “Olivia fell asleep before lunch,” Emma said, as Sam unlocked the car. “And Mitchell fell asleep after lunch. And Karen didn’t come until after recess because she didn’t wake up until then.”

  Sam said, “Yeah, a lot of people are having the same problem as…” He cut himself off, unwilling to commit to any particular tense. As you had? As you have?

  “But how will everyone stay friends if they can’t see each other?” Emma demanded indignantly, as if this whole state of affairs had been decreed by someone who just needed to be told what a terrible idea it was.

  “People stay friends when their friends get sick,” Sam replied. “Or when they go and live somewhere else. You don’t have to see someone every day to be their friend.”

  “No,” Emma agreed reluctantly. She adjusted her seatbelt. “But I want to.”

  Sam pulled the door shut beside him. He said, “Do you want to stay friends with Natalie?”

  “Yes.”

  “Then you’ll stay friends with Natalie. Even if it’s hard, even if it’s complicated, you’ll find a way to do it.”

  When they arrived home, Laura’s car was in the driveway. Emma ran inside, calling out to her mother; Sam had thought she was going to be on site all day, but maybe there’d been a change in the schedule.

  He found her in the bedroom, sitting on the edge of the bed, staring at the wall. Emma had stopped in the doorway, confused.

  “What’s wrong?” Sam asked.

  “There was an accident,” Laura said.

  He turned to Emma. “Can you go and put your books away?”

  Emma nodded uneasily and retreated.

  Laura said, “One of the operators swung a crane into the scaffolding. Three people
are dead, and five are in hospital.”

  Sam bowed his head. It sounded like something that should have been impossible. “So was it equipment failure?”

  “No,” she replied. “We’ve got video from inside the cab. The operator just kept his hand on the lever.”

  “Why? Was he having a heart attack?”

  “No. He closed his eyes and fell asleep.”

  5

  Halfway through the lesson on Al-Karaji’s triangle, two new students entered the room quietly, hung their dripping umbrellas over the bucket, and took seats at the back. Sam paused to greet them, then resumed, glad he’d managed to iron out the sound problems that had plagued his last few recordings, so they’d be able to play everything back from the start if they needed to.

  The rain came down more heavily, slanted now, striking the window panes on the southern wall with tympanic effect, but he raised his voice and pressed on. “The number of ways you can get x cubed y squared in this row is the number of ways we got x squared y squared in the row above, six, plus the number of ways we got x cubed y, four, for a total of ten. Every time, we’re just adding two numbers from above to get the ones below and in between them. So we ought to be able to guess a formula for the numbers in any given row, and then prove it by induction.”

  Hands shot up, gratifyingly, and Sam wrote each proposal on the blackboard. He glanced at the storm outside, and dared to marvel at the one small upside of the syndrome: not long ago, on a winter’s afternoon in a cozy room like this, half the class would have been dozing off, but even at two in the morning these runners seemed impervious to everything that might once have been conducive to a surreptitious nap.

  At the end of the lesson, a group of students hung around, hunting for fresh identities between the binomial coefficients while they waited to spend a few minutes with their other-phase friends who were only now arriving. Sam walked down the corridor to the grade three classroom, where Emma was in the middle of a cross-temporal exchange of her own. She stood in a group of a dozen other girls, but it was easy to tell from their states of dampness that about half had just come in from the rain.

  He kept his distance, reluctant to do anything to curtail the meeting, but after a couple of minutes the new teacher arrived and ejected everyone whose school day was officially over. Sam fished his phone from his pocket and checked the carpool app; he was scheduled to give three of Emma’s friends a ride home. “Sandra? Martin? Chloe?” he called out hopefully. No one responded, but the app showed him mug shots; he spotted the kids and corralled them toward the car.

  As he drove through the rain, Sam concentrated on the road, but it was impossible to ignore his passengers’ conversation. “We’ll visit you in the hospital,” Martin promised Chloe.

  “You won’t be awake for visiting hours,” Chloe replied.

  “They should let us come any time!” Sandra protested.

  But Chloe was resigned to the impending separation. “I won’t be awake when you want to come.”

  When Sam had dropped off all three, he asked Emma, “What’s the time in your head?”

  “Ten past three.”

  He checked his watch. The second row of digits, which he’d programmed to follow her phase, was only two minutes out—and Emma never claimed greater precision than five minutes herself.

  “So Chloe’s getting the implant?”

  “Yes,” Emma confirmed. “Her parents aren’t rich, but her grandmother’s paying.”

  Sam hesitated. “You know it’s not the cost that’s stopping us? We could probably get a loan to cover it. I just don’t think the safety record’s good enough yet.”

  Emma said, “I don’t want it anyway.”

  “I know. But in a couple of years, when the surgeons have had more practice and the technology’s improved…”

  Emma sighed, irritated. “I told you, I don’t want it. Ever!”

  As soon as they pulled into the driveway, Emma flung the door open. Sam watched as she ran to the porch; he could see her umbrella cinched in place in one of the net pockets at the side of her backpack.

  He followed her, taking more care to stay dry, and by the time he was inside she’d disappeared into her room. He took his shoes off and trod lightly down the hall to the office. It was just after four, and Laura would be up at six; he could probably get most of his marking done before the three of them were due to have breakfast together.

  He switched on the computer and checked his news feed. A story that had broken fifteen minutes ago had rocketed to the top: “Gang ‘hacked your sleep,’ wants cash for cure.” Sam assumed it was a beat-up, but he followed the link anyway. Nothing was going to rival the Onion’s “Uber Sleep rolls out replacement for Sandman; CEO plays down ‘teething problems,’” but intent had long ago ceased to be a prerequisite for satire.

  According to the story, a group calling themselves the Time Thieves had claimed responsibility for the free-running syndrome, and were soliciting offers from governments for exclusive access to the cure. The starting price in this auction was a trillion US dollars.

  “This is less than one percent of the estimated loss to global GDP to date,” the self-proclaimed biohackers had noted, citing a study by a team of World Bank economists to back up the figure. Fair enough, then, Sam thought. The email scammers offering him ancient Chinese herbs to realign his family’s circadian rhythms for sixty dollars a bottle were clearly undercharging.

  He was about to close the browser and get to work when he realized he’d skipped a paragraph near the top of the story, distracted by the astronomical sum below. “As evidence for their claims, the Time Thieves have published a digital key that decrypts a coded message describing the condition’s symptoms, which was posted on social media accounts six months before the first cases were reported.” Sam was skeptical; would it be that hard to hack a Twitter or Facebook post so it seemed to predate the outbreak? But then he searched for other coverage of the story that went into more technical details.

  The times in question were not just social media metadata. Digital hashes of the message had been sent to half a dozen reputable time-stamping authorities, who’d used their private encryption keys to sign and date what they’d received, allowing anyone to verify that the message really had been signed at the times being claimed. But to counter any suggestion that the top six cybersecurity organizations in the world might have all been hacked—or been willing accomplices to fraud—the Time Thieves had also embedded the same hashes into several globally distributed block chains that offered their own kinds of certification.

  Sam read through the full text of the decrypted post. Though its authors spelled out the symptoms of the coming plague clearly enough, they were coy when it came to the biochemistry, sprinkling in just enough jargon to suggest that they knew their target intimately, without revealing anything about the particular spanner they’d thrown into the works. A virus? A toxin? These and other details remained behind a very high paywall.

  The current ransom demands had been written in a tone befitting a Sotheby’s catalog, but this screed from (supposedly) two years ago was a boastful, pretentious rant, full of the kind of raw self-aggrandizement only to be expected from someone who believed they’d devised a foolproof means to take the whole world hostage and come out the other end wealthier than a middle-sized nation. There were even some bad puns about the WannaCry computer virus—two of the key proteins in the circadian clock being the cryptochromes, CRY1 and CRY2—as the Time Thieves gloated about their own, stupendously greater feat. Sam couldn’t help being goaded into anger, which in turn swayed him toward belief, though the fact that the document rang true as the heady manifesto of a gang of sociopaths would be by far the least challenging of all the forgeries required if the whole thing was actually a hoax.

  The response from political leaders so far had been cautious; everyone who’d spoken had condemned the extortion attempt, but they’d described any link to the syndrome itself in hypothetical terms, and stressed that law
enforcement agencies were still investigating the claims.

  Sam rather hoped that behind this bland facade, someone had already located the perpetrators and dispatched a team of commandoes to liberate the cure with extreme prejudice. Along with the economic damage, there had been at least half a million deaths. His own family had been lucky; as the gears that had linked them to the world had stopped meshing, they’d managed to adapt to the changes without descending into poverty. But all the accidents on the roads, in the air, and at sea, all the fatalities at building sites and factories were no different from the acts of a sniper, and the slow torture as loved ones had been dragged into different phases was as cruel as any forced exile. He’d gladly see the fuckers who’d done this reduced to bloody smears on the walls of their basement lab.

  He closed the browser and tried to calm himself. He had work to do, and neither his Zero Dark Thirty fantasies nor any other follow-up was likely to be imminent. He believed that these criminals had done what they claimed, but that didn’t guarantee that they were in possession of a cure, let alone that anyone on the planet would be willing to pay what they were asking.

  6

  None of Sam’s students could focus on the lesson he’d prepared, so he made the best of the situation.

  “A hash function takes some data, like a string of text, and gives you a single number that’s a whole lot shorter than the original message.” He drew a big box full of squiggles, joined by an arrow to a small box full of digits. “The correspondence can’t be unique, though; there are billions of messages that have the same hash code. So why doesn’t that matter? If someone shows you a message today that gives the hash X, along with proof that someone you trust saw that same number, X, two years ago … why should that be enough to persuade you that they actually wrote the whole message back then?”