The Time Traveler's Almanac

“All of this would be impossible without our continued ownership of the timegate. You already know the essentials. What you may not be aware of is that it is a unique, easily depleted resource. The timegate allows us to open wormholes connecting two openings in four-dimensional space-time. But the exclusion principle prevents two such openings from overlapping in time. Tear-up and tear-down is on the order of seven milliseconds, a seemingly tiny increment when you compare it to the trillion-year span that falls within our custody. But when you slice a period of interest into fourteen-millisecond chunks, you run out of time fast. Each such span can only ever be touched by us once, connected to one other place and time of our choosing.

“Stasis Control thus has access to a theoretical maximum of 5.6 times 1021 slots across the totality of our history – but our legion of humanity comes perilously close, with a total of 2 times 10 19 people. Many of the total available slots are reserved for data, relaying the totality of recorded human history to the Library – fully ninety-six percent of humanity lives in eras where ubiquitous surveillance or personal life-logging technologies have made the recording of absolute history possible, and we obviously need to archive their lifelines. Only the ur-historical prelude to Stasis, and periods of complete civilizational collapse and Reseeding, are not being monitored in exhaustive detail.

“To make matters worse: in practice there are far fewer slots available for actual traffic, because we are not, as a species, well equipped for reacting in spans of less than a second. The seven-millisecond latency of a timegate is shorter by an order of magnitude than the usual duration of a gate used for transport.

“We dare not use gates for iterated computational processes, or to open permanent synchronous links between epochs, and while we could in theory use it to enable a single faster-than-light starship, that would be horribly wasteful. So we are limited to blink-and-it’s-gone wormholes connecting time slices of interest. And we must conclude that the slots we allocate to temporal traffic are a scarce resource because—”

Yarrow paused and glanced across her audience. Pierce shifted slightly on his stool, a growing tension in his crotch giving his distraction a focus. Her gaze lingered on him a moment too long, as if she sensed his inattention: the slight hint of amusement, imperceptible microexpressions barely glimpsed at the corners of her mouth, sent a panicky shiver up his spine. She’s going to ask questions, he realized, as she opened her lips. “What applications of the timegate are ruled out by the slot latency period, class? Does anyone know? Student Pierce? What do you know?” She looked at him directly, expectantly. The half smile nibbled at her cheeks, but her eyes were cool.

“I, um, I don’t—” Pierce flailed for words, dragged back to the embarrassing present from his sensual daydream. “The latency period?”

“You don’t what?” Honorable Scholar Yarrow raised one perfect eyebrow in feigned disbelief at his fluster. “But of course, Student Pierce. You don’t. That has always been your besetting weakness: you’re easily distracted. Too curious for your own good.” Her smile finally broke, icy amusement crinkling around her eyes. “See me in my office after the tutorial,” she said, then turned her attention back to the rest of the class, leaving him to stew in fearful anticipation. “I do hope you have been paying more attention—”

The rest of Yarrow’s lecture slid past Pierce in a delirium of embarrassment as she spoke of deep time, of salami-sliced vistas of continental drift and re-formation, of megayears devoted to starlifting and the frozen, lifeless gigayears during which the Earth had been dislodged from its celestial track, to drift far from the sun while certain necessary restructuring was carried out. She knows me, he realized sickly, watching the pale lips curl around words that meant nothing and everything. She’s met me before. These things happened in the Stasis; the formal etiquette was deliberate padding to break the soul-shaking impact of such collisions with the consequences of your own future. She must think I’m an idiot—

The lecture ended in a flurry of bowing and dismissals. Confused, Pierce found himself standing before the Scholar on the roof of the world, beneath the watching moon. She was very beautiful, and he was utterly mortified. “Honorable Scholar, I don’t know how to explain, I—”

“Silence.” Yarrow touched one index finger to his lips. His nostrils flared at the scent of her, floral and strange. “I told you to see me in my office. Are you coming?”

Pierce gaped at her. “But Honorable Scholar, I—”