Galactic Empires

by Neil Clarke

  It had been twenty-eight thousand years since they’d left Najib. All her children and grandchildren had almost certainly chosen death long ago. No messages had been sent after them to Nazdeek; Leila had asked for that silence, fearing that it would be unbearably painful to hear news, day after day, to which she could give no meaningful reply, about events in which she could never participate. Now she regretted that. She wanted to read about the lives of her grandchildren, as she might the biography of an ancestor. She wanted to know how things had ended up, like the time traveler she was.

  A second month of observation passed, with nothing. A data feed reaching them from Nazdeek was equally silent. For any new hint of the beam’s location to reach Nazdeek, and then the report of that to reach Trident, would take thousands of years longer than the direct passage of the beam itself, so if Nazdeek saw evidence that the beam was “still” on course, that would be old news about a pulse they had not been here to intercept. However, if Nazdeek reported that the beam had shifted, at least that would put them out of their misery immediately, and tell them that Trident had been built too late.

  Jasim made a vegetable garden on the porch and grew exotic food in the starlight. Leila played along, and ate beside him; it was a harmless game. They could have painted anything at all around the house: any planet they’d visited, drawn from their memories, any imaginary world. If this small pretense was enough to keep them sane and anchored to reality, so be it.

  Now and then, Leila felt the strangest of the many pangs of isolation Trident induced: here, the knowledge of the galaxy was no longer at her fingertips. Their descriptions as travelers had encoded their vast personal memories, declarative and episodic, and their luggage had included prodigious libraries, but she was used to having so much more. Every civilized planet held a storehouse of information that was simply too bulky to fit into Trident, along with a constant feed of exabytes of news flooding in from other worlds. Wherever you were in the galaxy, some news was old news, some cherished theories long discredited, some facts hopelessly out of date. Here, though, Leila knew, there were billions of rigorously established truths—the results of hundreds of millennia of thought, experiment, and observation—that had slipped out of her reach. Questions that any other child of the Amalgam could expect to have answered instantly would take twelve hundred years to receive a reply.

  No such questions actually came into her mind, but there were still moments when the mere fact of it was enough to make her feel unbearably rootless, cut adrift not only from her past and her people, but from civilization itself.

  Trident shouted: “Data!”

  Leila was halfway through recording a postcard to the Nazdeek Snakes. Jasim was on the porch watering his plants. Leila turned to see him walking through the wall, commanding the bricks to part like a gauze curtain.

  They stood side by side, watching the analysis emerge.

  A pulse of gamma rays of the expected frequency, from precisely the right location, had just washed over Trident. The beam was greatly attenuated by distance, not to mention having had most of its energy intercepted by its rightful owner, but more than enough had slipped past and reached them for Trident to make sense of the nature of the pulse.

  It was, unmistakably, modulated with information. There were precisely repeated phase shifts in the radiation that were unimaginable in any natural gamma ray source, and which would have been pointless in any artificial beam produced for any purpose besides communication.

  The pulse had been three seconds long, carrying about ten-to-the-twenty-fourth bits of data. The bulk of this appeared to be random, but that did not rule out meaningful content, it simply implied efficient encryption. The Amalgam’s network sent encrypted data via robust classical channels like this, while sending the keys needed to decode it by a second, quantum channel. Leila had never expected to get hold of unencrypted data, laying bare the secrets of the Aloof in an instant. To have clear evidence that someone in the bulge was talking to someone else, and to have pinned down part of the pathway connecting them, was vindication enough.

  There was more, though. Between the messages themselves, Trident had identified brief, orderly, unencrypted sequences. Everything was guesswork to a degree, but with such a huge slab of data statistical measures were powerful indicators. Part of the data looked like routing information, addresses for the messages as they were carried through the network. Another part looked like information about the nodes’ current and future trajectories. If Trident really had cracked that, they could work out where to position its successor. In fact, if they placed the successor close enough to the bulge, they could probably keep that one observatory constantly inside the spill from the beam.

  Jasim couldn’t resist playing devil’s advocate. “You know, this could just be one part of whatever throws the probes back in our faces, talking to another part. The Aloof themselves could still be dead, while their security system keeps humming with paranoid gossip.”

  Leila said blithely, “Hypothesize away. I’m not taking the bait.”

  She turned to embrace him, and they kissed. She said, “I’ve forgotten how to celebrate. What happens now?”

  He moved his fingertips gently along her arm. Leila opened up the scape, creating a fourth spatial dimension. She took his hand, kissed it, and placed it against her beating heart. Their bodies reconfigured, nerve-endings crowding every surface, inside and out.

  Jasim climbed inside her, and she inside him, the topology of the scape changing to wrap them together in a mutual embrace. Everything vanished from their lives but pleasure, triumph, and each other’s presence, as close as it could ever be.

  VII

  “Are you here for the Listening Party?”

  The chitinous heptapod, who’d been wandering the crowded street with a food cart dispensing largesse at random, offered Leila a plate of snacks tailored to her and Jasim’s preferences. She accepted it, then paused to let Tassef, the planet they’d just set foot on, brief her as to the meaning of this phrase. People, Tassef explained, had traveled to this world from throughout the region in order to witness a special event. Some fifteen thousand years before, a burst of data from the Aloof’s network had been picked up by a nearby observatory. In isolation, these bursts meant very little; however, the locals were hopeful that at least one of several proposed observatories near Massa, on the opposite side of the bulge, would have seen spillage including many of the same data packets, forty thousand years before. If any such observations had in fact taken place, news of their precise contents should now, finally, be about to reach Tassef by the longer, disk-based routes of the Amalgam’s own network. Once the two observations could be compared, it would become clear which messages from the earlier Eavesdropping session had made their way to the part of the Aloof’s network that could be sampled from Tassef. The comparison would advance the project of mapping all the symbolic addresses seen in the data onto actual physical locations.

  Leila said, “That’s not why we came, but now we know, we’re even more pleased to be here.”

  The heptapod emitted a chirp that Leila understood as a gracious welcome, then pushed its way back into the throng.

  Jasim said, “Remember when you told me that everyone would get bored with the Aloof while we were still in transit?”

  “I said that would happen eventually. If not this trip, the next one.”

  “Yes, but you said it five journeys ago.”

  Leila scowled, preparing to correct him, but then she checked and he was right.

  They hadn’t expected Tassef to be so crowded when they’d chosen it as their destination, some ten thousand years before. The planet had given them a small room in this city, Shalouf, and imposed a thousand-year limit on their presence if they wished to remain embodied without adopting local citizenship. More than a billion visitors had arrived over the last fifty years, anticipating the news of the observations from Massa, but unable to predict the precise time it would reach Tassef because the details o
f the observatories’ trajectories had still been in transit.

  She confessed, “I never thought a billion people would arrange their travel plans around this jigsaw puzzle.”

  “Travel plans?” Jasim laughed. “We chose to have our own deaths revolve around the very same thing.”

  “Yes, but we’re just weird.”

  Jasim gestured at the crowded street. “I don’t think we can compete on that score.”

  They wandered through the city, drinking in the decades-long-carnival atmosphere. There were people of every phenotype Leila had encountered before, and more: bipeds, quadrupeds, hexapods, heptapods, walking, shuffling, crawling, scuttling, or soaring high above the street on feathered, scaled, or membranous wings. Some were encased in their preferred atmospheres; others, like Leila and Jasim, had chosen instead to be embodied in ersatz flesh that didn’t follow every ancestral chemical dictate. Physics and geometry tied evolution’s hands, and many attempts to solve the same problems had converged on similar answers, but the galaxy’s different replicators still managed their idiosyncratic twists. When Leila let her translator sample the cacophony of voices and signals at random, she felt as if the whole disk, the whole Amalgam, had converged on this tiny metropolis.

  In fact, most of the travelers had come just a few hundred light-years to be here. She and Jasim had chosen to keep their role in the history of Eavesdropping out of their précis, and Leila caught herself with a rather smug sense of walking among the crowd like some unacknowledged sage, bemused by the late-blooming, and no doubt superficial, interest of the masses. On reflection, though, any sense of superior knowledge was hard to justify, when most of these people would have grown up steeped in developments that she was only belatedly catching up with. A new generation of observatories had been designed while she and Jasim were in transit, based on “strong bullets”: specially designed femtomachines, clusters of protons and neutrons stable only for trillionths of a second, launched at ultra-relativistic speeds so great that time dilation enabled them to survive long enough to collide with other components and merge into tiny, shortlived gamma-ray observatories. The basic trick that had built Trident had gone from a one-off gamble into a miniaturized, mass-produced phenomenon, with literally billions of strong bullets being fired continuously from thousands of planets around the inner disk.

  Femtomachines themselves were old hat, but it had taken the technical challenges of Eavesdropping to motivate someone into squeezing a few more tricks out of them. Historians had always understood that in the long run, technological progress was a horizontal asymptote: once people had more or less everything they wanted that was physically possible, every incremental change would take exponentially longer to achieve, with diminishing returns and ever less reason to bother. The Amalgam would probably spend an eon inching its way closer to the flatline, but this was proof that shifts of circumstance alone could still trigger a modest renaissance or two, without the need for any radical scientific discovery or even a genuinely new technology.

  They stopped to rest in a square, beside a small fountain gushing aromatic hydrocarbons. The Tassef locals, quadrupeds with slick, rubbery hides, played in the sticky black spray then licked each other clean.

  Jasim shaded his eyes from the sun. He said, “We’ve had our autumn child, and we’ve seen its grandchildren prosper. I’m not sure what’s left.”

  “No.” Leila was in no rush to die, but they’d sampled fifty thousand years of their discovery’s consequences. They’d followed in the wake of the news of the gamma ray signals as it circled the inner disk, spending less than a century conscious as they sped from world to world. At first they’d been hunting for some vital new role to play, but they’d slowly come to accept that the avalanche they’d triggered had out-raced them. Physical and logical maps of the Aloof’s network were being constructed, as fast as the laws of physics allowed. Billions of people on thousands of planets, scattered around the inner rim of the Amalgam’s territory, were sharing their observations to help piece together the living skeleton of their elusive neighbors. When that project was complete it would not be the end of anything, but it could mark the start of a long hiatus. The encrypted, classical data would never yield anything more than traffic routes; no amount of ingenuity could extract its content. The quantum keys that could unlock it, assuming the Aloof even used such things, would be absolutely immune to theft, duplication, or surreptitious sampling. One day, there would be another breakthrough, and everything would change again, but did they want to wait a hundred thousand years, a million, just to see what came next?

  The solicitous heptapods—not locals, but visitors from a world thirty light-years away who had nonetheless taken on some kind of innate duty of hospitality—seemed to show up whenever anyone was hungry. Leila tried to draw this second one into conversation, but it politely excused itself to rush off and feed someone else.

  Leila said, “Maybe this is it. We’ll wait for the news from Massa, then celebrate for a while, then finish it.”

  Jasim took her hand. “That feels right to me. I’m not certain, but I don’t think I’ll ever be.”

  “Are you tired?” she said. “Bored?”

  “Not at all,” he replied. “I feel satisfied. With what we’ve done, what we’ve seen. And I don’t want to dilute that. I don’t want to hang around forever, watching it fade, until we start to feel the way we did on Najib all over again.”

  “No.”

  They sat in the square until dusk, and watched the stars of the bulge come out. They’d seen this dazzling jewelled hub from every possible angle now, but Leila never grew tired of the sight.

  Jasim gave an amused, exasperated sigh. “That beautiful, maddening, unreachable place. I think the whole Amalgam will be dead and gone without anyone setting foot inside it.”

  Leila felt a sudden surge of irritation, which deepened into a sense of revulsion. “It’s a place, like any other place! Stars, gas, dust, planets. It’s not some metaphysical realm. It’s not even far away. Our own home world is twenty times more distant.”

  “Our own home world doesn’t have an impregnable fence around it. If we really wanted to, we could go back there.”

  Leila was defiant. “If we really wanted to, we could enter the bulge.”

  Jasim laughed. “Have you read something in those messages that you didn’t tell me about? How to say ‘open sesame’ to the gatekeepers?”

  Leila stood, and summoned a map of the Aloof’s network to superimpose across their vision, crisscrossing the sky with slender cones of violet light. One cone appeared head-on, as a tiny circle: the beam whose spillage came close to Tassef. She put her hand on Jasim’s shoulder, and zoomed in on that circle. It opened up before them like a beckoning tunnel.

  She said, “We know where this beam is coming from. We don’t know for certain that the traffic between these particular nodes runs in both directions, but we’ve found plenty of examples where it does. If we aim a signal from here, back along the path of the spillage, and we make it wide enough, then we won’t just hit the sending node. We’ll hit the receiver as well.”

  Jasim was silent.

  “We know the data format,” she continued. “We know the routing information. We can address the data packets to a node on the other side of the bulge, one where the spillage comes out at Massa.”

  Jasim said, “What makes you think they’ll accept the packets?”

  “There’s nothing in the format we don’t understand, nothing we can’t write for ourselves.”

  “Nothing in the unencrypted part. If there’s an authorization, even a checksum, in the encrypted part, then any packet without that will be tossed away as noise.”

  “That’s true,” she conceded.

  “Do you really want to do this?” he said. Her hand was still on his shoulder, she could feel his body growing tense.

  “Absolutely.”

  “We mail ourselves from here to Massa, as unencrypted, classical data that anyone can read, a
nyone can copy, anyone can alter or corrupt?”

  “A moment ago you said they’d throw us away as noise.”

  “That’s the least of our worries.”

  “Maybe.”

  Jasim shuddered, his body almost convulsing. He let out a string of obscenities, then made a choking sound. “What’s wrong with you? Is this some kind of test? If I call your bluff, will you admit that you’re joking.”

  Leila shook her head. “And no, it’s not revenge for what you did on the way to Trident. This is our chance. This is what we were waiting to do—not the Eavesdropping, that’s nothing! The bulge is right here in front of us. The Aloof are in there, somewhere. We can’t force them to engage with us, but we can get closer to them than anyone has ever been before.”

  “If we go in this way, they could do anything to us.”

  “They’re not barbarians. They haven’t made war on us. Even the engineering spores come back unharmed.”

  “If we infest their network, that’s worse than an engineering spore.”

  “‘Infest’! None of these routes are crowded. A few exabytes passing through is nothing.”

  “You have no idea how they’ll react.”

  “No,” she confessed. “I don’t. But I’m ready to find out.”

  Jasim stood. “We could send a test message first. Then go to Massa and see if it arrived safely.”

  “We could do that,” Leila conceded. “That would be a sensible plan.”

  “So you agree?” Jasim gave her a wary, frozen smile. “We’ll send a test message. Send an encyclopedia. Send greetings in some universal language.”

  “Fine. We’ll send all of those things first. But I’m not waiting more than one day after that. I’m not going to Massa the long way. I’m taking the shortcut, I’m going through the bulge.”

  VIII

  The Amalgam had been so generous to Leila, and local interest in the Aloof so intense, that she had almost forgotten that she was not, in fact, entitled to a limitless and unconditional flow of resources, to be employed to any end that involved her obsession.