The receiving array of Relay Station Arc developed a fault just after Jiyeon's night shift began. The incoming waveform of Antenna 3 buckled, and the cooling structure of the Translation Core lit an amber warning lamp. Jiyeon set down her coffee and walked to the console. The control room's lighting was in night mode, so only the glow of the instrument panels reflected off the walls. The waveform's phase was off by 8.3 seconds. In 42 years, the timing deviation in communications with the Rakis Intelligence had never once exceeded 2 seconds.
When Jiyeon opened the log, a single unclassified Rakis message was lodged in the receiving queue. Time of arrival: 7 minutes ago. The Translation Core had refused to process it and shunted it into quarantine. Jiyeon checked the quarantined message's header. The identifying signature was empty. Every message from the Rakis Intelligence had to contain the sending entity's identifying signature—the unique signal pattern that served as its name, the way a human has one. The Translation Core could not process a message without a signature. An utterance without a signature was a sentence without a speaker, and a sentence without a speaker was not a thing to be translated.
Jiyeon noted the time and the situation in the duty log, then picked up the intercom handset beside the console. The signal rang three times before an answer came.
“What.”
Jaehan's voice was still half-asleep. The station's translation supervisor. He had been posted here 14 years before Jiyeon, and he was the one who had designed the communication protocol with the Rakis Intelligence.
“Antenna 3, deviation 8.3 seconds.” The hum of the ventilation filled the gap. “And there's a message in quarantine with no identifying signature.”
Through the receiver came the creak of a bed frame.
“On my way.”
It took Jaehan 4 minutes to reach the control room. He shuffled in dragging his slippers and dropped into the empty chair at the console. His hair was mashed flat on one side, and a pillow crease was pressed into the corner of his mouth. He pulled the quarantined message's raw data onto the screen and magnified the waveform. There was a moment when his fingers went still on the trackball. Jaehan's shoulders rose a fraction.
“This isn't missing a signature.”
Jaehan pointed at the screen. A faint pattern lay buried in the waveform's lower band.
“There is a signature in here—it's just one that isn't in the current database. The Core logged it as an identification failure.”
Jiyeon dragged her chair over and looked at the screen. The pattern in the lower band resembled the structure of the existing Rakis signatures, but its frequency band was subtly different.
“Is it an old signature?”
Jaehan shook his head.
“This frequency band has never been registered anywhere in the Rakis protocol.”
Jiyeon leaned back in her chair and looked up at the control room ceiling. Relay Station Arc sat at the edge of Rakis space, 6.4 light-years from Earth. A cylindrical structure 340 meters long. Nine permanent crew. Of those, only two handled translation work: Jiyeon and Jaehan. Communication with Earth took 6.4 years one way. Whatever judgment this message called for had to be made inside this control room.
Jaehan brought up the Translation Core's auxiliary module. It was the emergency procedure that bypassed the identifying signature and extracted only the body of the message. The Rakis utterance structure unspooled onto the screen. A multidimensional trajectory. Jiyeon read the shape of that trajectory. A Rakis utterance was motion through a vector space. The direction of the trajectory carried meaning, its velocity carried tense, its curvature carried the speaker's emotional state. The Translation Core was the algorithm that mapped this trajectory into human language, and that algorithm rested on a single premise. The identifying signature must come first. Without a signature there was no reference point for the trajectory, and without a reference point the meaning of a direction could not be pinned down.
“The body structure is normal,” Jaehan said, scrolling.
“The trajectory's curvature is within the Rakis standard range too. The signature is the only problem.”
He swiveled his chair and looked at Jiyeon.
“What do you think happens if we translate without a signature?”
Jiyeon bit the inside of her lip. The taste of iron spread through her mouth.
“With no reference point, the same trajectory gets read as several meanings. One message could produce three or more different translations.”
“Exactly. That's why the signature is Article 1 of the protocol. A clause I wrote 42 years ago.”
Jaehan opened the database archive. 42 years of Rakis communication records. 220,000 messages. Every one of them contained an identifying signature. Jaehan sorted the shift in signature patterns along a time axis. Onto the screen came 42 years of signature evolution. The early signatures were simple. Short signals made of 3 frequency patterns. As the years passed, the patterns grew more complex. At year 10 there were signatures of 7 patterns, at year 20 of 14, at year 40 of 31.
Jiyeon watched the graph and asked.
“The rate at which the signatures grow complex isn't constant.”
Jaehan nodded.
“Rakis renews its own identity as time goes on. It's similar to a human changing with age, but there's one decisive difference. Humans change, yet they don't throw away their past selves. They carry them around in the form of memory. Rakis is different. When it renews itself, it discards the previous version's signature. Only the present self is the one and only self.”
Jiyeon's finger came down on a point on the screen. There was one stretch of the graph where the signature complexity dropped off sharply. 37 years ago. The moment a particular individual's signature, once 31 patterns, suddenly shrank to 9.
"What is this?"
Jaehan's eyes narrowed. He magnified the screen. And for a long while he said nothing. Only the low drone of the control room's ventilation and the fan noise seeping from the cooling structure went on.
"So this was here."
Jaehan muttered, almost to himself. He opened the record from 37 years ago. The identification number of the individual whose signature had contracted was Rakis-0017. The record from back then carried an annotation in Jaehan's own hand. 'Rakis-0017 signature change. Toward simplification. Reason unknown. Change falls within protocol range, therefore processed as normal.' Jaehan pulled his eyes from the screen. The chair's backrest creaked.
"Processed as normal."
Jaehan turned over the words he'd written 37 years ago.
"I wrote 'processed as normal.'"
Jiyeon watched. There was a tightness at the corners of Jaehan's mouth.
"And now you're saying it wasn't normal?"
Jaehan turned his head and looked at her. His eyes looked dry.
"0017 contracting its signature—now that I think about it, that was it returning to an earlier version. Not renewal but reversal. Rakis rolled its own identity back to a prior state. I should have caught it then."
"Why didn't you?"
At Jiyeon's question Jaehan closed his mouth for a moment. Beyond the control room window the faint nebula-light of the Rakis territory was coming in. In the dark of the room that light drew the two of them in dim outline. A purple shot through with red.
"When I designed the protocol 42 years ago, I assumed a signature only ever changes in the direction of greater complexity. That identity accumulates. That the present piles on top of the past. I carried a human premise straight over."
Jaehan's hand gripped the edge of the console. Until the knuckles went white.
Jiyeon set the quarantined message's signature pattern against the contracted signature of Rakis-0017 from 37 years ago. The two patterns lay side by side on the screen. A match of 97.6 percent. Jiyeon's mouth opened, then closed.
"It's 0017," she said. "0017 in the state it reverted to 37 years ago. But the signature it's sending now is even more contracted than the one from 37 years ago. 5 patterns. It's gone further back."
Jaehan rose from his chair. He crossed the control room and walked up to the cooling structure that housed the Translation Core. Cold air flowed off the surface of the structure. An orange warning light blinked over his face.
"You know why the Core is rejecting 0017?" Jaehan said, leaning his back against the structure. "42 years ago I wrote the signature-verification rule like this. 'The current signature must be of complexity greater than or equal to the immediately preceding signature.' If the complexity drops, the Core judges it a forgery and rejects it. The premise that identity does not retreat. A premise I made."
Jiyeon looked at Jaehan from where she sat. The chill from the cooling structure was spreading across the control room floor. Her ankles were cold.
"So 0017 going back to an earlier state—that makes it, in our protocol, an individual that doesn't exist?"
"That's right."
"But it does exist. It's sending this very message right now."
Jaehan said nothing.
Jiyeon attempted a translation of the message body. Running the Core in signature-bypass mode meant interpreting the trajectory with no reference point. The result was just as Jaehan had predicted. From a single trajectory came three translations. Jiyeon put all three up side by side on the screen.
The first: 'My earlier self was an error. My present self is before the error. This is me.' The second: 'There is a gap between my earlier self and my present self. I speak from this side of the gap.' The third: 'I have come back. Accept me.'
As Jaehan read the three sentences his expression shifted. At the first and the third his mouth stayed set. At the second his eyes trembled faintly.
"The second is closest."
Jiyeon looked at him.
"How do you know?"
"I don't. But when I wrote 'processed as normal' 37 years ago, I chose it without knowing then, either. Same as now."
Jiyeon swiveled her chair and looked at the control room window. Nebula-light bled across the glass. She checked the clock. 2 hours had passed since 0017's message arrived. The protocol with the Rakis Intelligence carried a deadline for acknowledgment. If an unclassified message went 4 hours without a response, the Rakis side would switch the communication channel to one-way. Once it went one-way, the human side could not transmit. A state of hearing only, unable to speak. 42 years of a two-way channel closing shut.
"We have to send a response," Jiyeon said. "If we modify the Core's signature verification so it recognizes 0017—"
"Change the signature verification and 42 years of protocol are voided." Jaehan cut in. "If the Core stops verifying the temporal direction of a signature, forged messages posing as past signatures get through too. The whole trust framework we've built up until now gets shaken."
"But it's not like we can get Earth headquarters' approval within 2 hours either."
"I know."
Jaehan stood at the console. On the screen, the source of the signature-verification rule was open. Code Jaehan had written 42 years ago. His own name and the date were noted in the comment. His fingers did not move above the keyboard. Jiyeon looked at that hand. The veins stood out on the back of it, and the creases were deep in the knuckles. “When I wrote this rule 42 years ago, I never got Rakis's consent.” Jaehan said. His voice was low. “I embedded a human concept of identity into the protocol and declared it a rule common to both sides. There was no way to confirm whether Rakis agreed. Because that confirmation itself is only possible through this very protocol.” Jiyeon didn't answer. The orange warning light on the cooling structure blinked at 2-second intervals. The light spread across Jaehan's back, then vanished.
Jaehan laid his hands on the keyboard. He began deleting the complexity condition from the signature-verification rule. The line reading 'the current signature must have a complexity greater than or equal to the previous signature' disappeared from the screen. In its place, a new condition was entered. 'Verify only the internal structural consistency of the signature. Disable time-direction verification.' His fingers never once stopped. When the revision was done, Jaehan leaned back against the chair. He closed his eyes. 3 seconds. The sound of the ventilation unit filled the gap between them. “This is a temporary measure.” Jaehan said, opening his eyes. “Whether Earth Headquarters approves it we won't know for another 6.4 years. Until then, responsibility for the security of every communication on this station is logged under my name.” Jiyeon nodded. “Shall I apply the revision?” Jaehan struck the enter key.
The Translation Core took 90 seconds to restart. The warning light on the cooling structure shifted from orange to green. 0017's messages, which had been quarantined, began passing through the Core. A translation surfaced on the screen. This time, only one. With a reference point established, the interpretations of the trajectory had converged.
'I remember the prior agreement. The self who agreed at that time is different from the self I am now. Must the self I am now go on honoring the agreement?'
Jiyeon read the translation and turned to Jaehan. His gaze was fixed on the screen. His lips were slightly parted. Jiyeon asked. “What agreement does it mean?” Jaehan answered slowly. “42 years ago, when we first opened communication, there was something that set the terms of contact between the two sides. Rakis would share stellar navigation data, and humans would guarantee the neutrality of the Rakis domain. 0017 is the Rakis representative entity that mediated that agreement at the time.”
Jiyeon's back came away from the chair. She tilted forward. “The representative entity reverted to a past state? It discarded the very self that made the agreement?” Jaehan nodded. Slowly. Heavily. “What 0017 is asking now is whether the current version of itself has to keep a promise made by an earlier version of itself.” Jiyeon's fingers pressed the edge of the console. The metal was cold.
Jaehan rose and walked the narrow passage of the control room. Past the fire extinguisher mounted on the wall, beneath the emergency-exit sign, past the 42nd-anniversary commemorative photo hanging on the wall—the station's 9 resident crew standing in a row—and stopped before the window. The station's outer wall was double-reinforced glass, with coolant circulating between the panes. When Jaehan pressed his hand to the glass, his palm cooled quickly. Nebula light lit half of his face. “Because of the protocol I wrote 42 years ago, 0017's question failed to arrive for 42 years. Because the Core rejected it. 0017 could have sent this question 37 years ago, and before that too. We simply never received it.”
Jiyeon reopened the incoming queue. With the Core's signature-verification rule changed, messages that had previously been rejected began to be reprocessed. New translations rose into the queue, one by one. Jiyeon counted the numbers and then stopped. 37. Over the span of 37 years, 37 messages sent by 0017 had been rejected by the Core and had lain dormant in the quarantine store. One each year. Without a single gap.
The translation of the first message was short. 'The self who remembers the agreement is gone. The self who cannot remember the agreement asks whether the agreement holds force.' Jiyeon scrolled the screen. 36 years ago, 35 years ago, 34 years ago. One each year. Variations on the same question, repeating. The core of the question did not change, but the trajectory of its expression differed from year to year. Each time, a different self was posing the same question. 37 distinct trajectories were converging upon a single question. Every time it renewed itself, 0017 had returned again to this question.
Jaehan turned from the window and said to Jiyeon, "We have to send a response."
Jiyeon looked at him. "What?"
Jaehan stood in front of the console. A single empty outbound field hung on the screen.
"For 37 years, what 0017 has been asking comes down to one thing. Whether a promise made by a past self binds the present self. The only ones who can answer that question are on the human side. Depending on what answer we send, the 42-year agreement either holds or dissolves."
Jiyeon looked at the outbound field. The cursor was blinking. 1 hour 43 minutes until the deadline.
"I'm still—"
Jiyeon started to speak and stopped, because Jaehan had already begun to type. She read the letters surfacing on the screen. 'The agreement rests not on a particular version of you, but on the contact between the two sides itself. Even if you change, the contact continues.' Jaehan stopped typing and looked at her.
"Well?"
Jiyeon read the screen again. Once. Twice.
"Isn't this a human premise too?"
Jaehan's hands lifted from the keyboard.
"You're right," he said. The strength had gone out of his voice.
"Humans hold that a promise stays valid no matter how the parties change. Whether Rakis sees it that way, I don't know."
Jiyeon deleted the sentence in the outbound field and typed a new one. 'We have received your question. All 37 of them. We need time to respond.' Jaehan read the screen, then looked at her. Jiyeon's hand rested over the send key.
"This isn't an answer," Jaehan said.
"It's buying time."
"You went 37 years without answering, and now there's some answer you can come up with inside 2 hours?"
Jaehan's mouth closed. Jiyeon pressed the send key. A transmission-confirmation tone sounded from the console. A short, high electronic tone rang out.
The control room went quiet again. The fan of the cooling structure came back into hearing. Jiyeon began to sort the receiving queue. She rearranged the 37 messages in chronological order and moved each translation into a document file. Jaehan stood at the window, watching the nebula-light. After a long while he spoke.
"37 years."
Jiyeon looked at him.
"Because I wrote the protocol wrong 42 years ago, 0017 couldn't reach us for 37 years."
Jiyeon didn't answer. She went on sorting the files. Only the sound of her fingers tapping the keyboard filled the control room.
0017's response arrived 6 minutes later. The translation surfaced on the screen. Jiyeon read it first. 'I grant the time. However, the route coordinates numbered 3 through 17, among the navigation data you received during the previous agreement period, contain an error of mine. Since it is data provided by the self I was at the time of the agreement, the self I am now does not vouch for it. I recommend verification.' Jaehan came back to the screen. He read. The color drained from his face. He dropped into the chair as though collapsing into it.
"Routes 3 through 17."
Jaehan's voice cracked.
"15 migration ships passed through those routes. The most recent one, 8 months ago."
Jaehan sat at the console and pulled up the route data. His fingers slipped twice on the keyboard. Jiyeon stood beside him and watched the screen. The trajectories of 15 migration ships appeared as lines across the map. 0017 had said it would not vouch for the coordinates of the routes those lines had crossed. Jiyeon's palms went damp. She wiped her hands against the sides of her trousers.
Jaehan got up from the chair and went to the communication panel. He set up an emergency transmission toward Earth. 6.4 years one way. Send it now, and Earth would receive it 6.4 years from now. But it had to be sent. The migration ship that had departed 8 months ago was still on its route. A warning that there might be an error in the route coordinates. Jaehan's hand stopped over the transmit key.
"If we'd received this message 37 years ago, we could have checked the routes of all 15 ships beforehand."
Jiyeon stood beside him and said, "Send it now."
Jaehan pressed the key. The transmission-confirmation tone rang through the control room. Jiyeon went back to 0017's message files and opened the 28th message. She began to read the next translation. Out in the corridor beyond the control room, the emergency lights blinked at even intervals, the fan of the cooling structure turned, and 37 translations stood lined up in rows on the screen.
