Brent looked down at the display, but his mind was elsewhere. Over a thousand years ago, before humanity had taken more than the first tentative steps into space, human scientists had pondered the absence of any alien contact. A scientist called Fermi had devised a famous paradox, concluding that an alien race that had evolved thousands of years before humanity should have filled up the galaxy long before the human race had appeared on the scene. He’d implied that the absence of any alien contact suggested that there were no other races in existence, a conclusion that had been hotly disputed at the time. The paradox hadn’t been solved until hundreds of years later. There were no other alien races because the Killers were systematically killing them off before they could become powerful enough to challenge their superiority. It still galled Brent that after a thousand years, after a fortnight spent studying the captured starship, humanity still had no idea why the Killers had embarked on their insane crusade. There seemed no logical reason for mass slaughter.
Or perhaps, he considered, there was a reason. Space was not a safe environment. The Killers might believe that it was kill or be killed, with no middle ground. Perhaps they didn’t dare trust any other race, regardless of its actual nature, or perhaps they had evolved to regard all other sentient forms of life as a possible threat. Human history had hundreds of examples of preemptive strikes mounted by human aggressors; was it really so unlikely that aliens would behave in the same way?
He smiled, bitterly. The Defence Force had been urged to study human pre-space science-fiction novels, in hopes of mining useful ideas from early conceptions of space warfare, and it had struck him how insanely hopeful most of those novels had been. They’d foreseen a great destiny for humanity, one where humanity dominated the entire galaxy, or founded mighty federations and empires, or even become superhuman amid the stars. They’d foreseen alien friends and enemies. Even the worst, the most depressing, hadn’t predicted the sheer bleakness of the universe, or the absence of all other forms of life, apart from one. Human imagination had proven itself to be far too limited.
“Cromwell,” he called. “Isolate all Killer bases on the display.”
“Yes, sir,” the AI said. The display removed all icons, but the dark circles representing Killer bases and star systems. “Do you wish to zoom in on the display?”
“Not at present,” Brent said, stroking his beard thoughtfully. “Just hold it right there…”
There were hundreds of known Killer bases in the galaxy, all being watched — from a safe distance, or what humanity devoutly hoped was a safe distance — by various starships, automated probes and listening posts. The Defence Force had vast resources to deploy in the defence of humanity — the Community was effectively a post-scarcity society — yet it was always short of manpower. It seemed to Brent that two-thirds of every generation grew up, took one look at the universe, and vanished permanently into virtual worlds that sheltered them from the truth. The remainder, if they had all joined the Defence Force, would have provided more than enough manpower, but not all chose to serve. They wanted to found new colonies, or flee out of the galaxy altogether, or follow their own careers. He had to admit that there were some pretty impressive artistic talents out there, but if the Killers ever decided to go after humanity and finish the job, the artists would be as helpless as their cousins in the VR worlds. Or, for that matter, the handful of human colonies struggling along on planetary surfaces without technology, or any other form of labour-saving device.
The thought reminded him of the brief civil war on Garden, one of the nastier incidents in the Community’s history. The colonists had been seduced into believing that a life without technology would be bliss and paradise, where they would frolic together under blue skies and there would be no Killer shadows hanging over their heads. The colony had barely made it past one winter without massive social unrest and demands from the colonists to bring in additional technology, or return to the stars. The leadership had refused and a bitter civil war had broken out. Eventually, the Defence Force had intervened and imposed a peace settlement, but the colony had collapsed a few years later. The survivors were still bitter about their experience, but they’d been lucky in one respect. There was no sign that the Killers had noticed their world.
“All right, Cromwell,” he said, as a seat formed out of the floor and he sat back in it. “Time to put your analytic capabilities to work. Why did the Killers choose those star systems?”
“Unknown,” the AI said, at once. “We have no data on why the Killers favour some systems over others.”
“True,” Brent agreed, wishing — not for the first time — for the massive flexibility and insight of the MassMind. “What do all those systems have in common?”
The AI seemed to pause, although Brent knew that that was merely a programmed conceit. Even the merest AI thought far faster than any human. Cromwell might have lacked the sheer processing power, coupled with human intuition, of the MassMind, but he still had access to more raw data than any human mind could comprehend. Brent didn’t fully trust the MassMind — its very nature made the concept of operational security a joke — but the AI was reliable. Sparta had nothing, but the best.
“They all include vast resources,” Cromwell said, finally. “The smallest observed system has seven rocky planets, two gas giants, three asteroid fields and a considerable amount of comets, space dust and other assorted debris. The largest observed system, up near the galactic core, includes nine gas giants and seven rocky worlds, along with two asteroid fields. The Killers would be able to build thousands of their starships from the resources in just one of their systems.”
“Gas giants,” Brent repeated, slowly. The debriefing session had included the suggestion, from Paula Handley, that the Killers had evolved in a gas giant, rather than an Earth-like world. The concept had surprised him — and left him wondering why no one had thought of it before — even though it seemed impossible. There was no supporting evidence, yet there was a considerable amount of indirect proof; the Killers, certainly, had never settled an Earth-like world. They seemed prepared, instead, to break them up for resources. “They all have gas giants in common.”
“Yes, sir,” Cromwell said. “They also have rocky planets and asteroid belts in common as well.”
Brent smiled wryly. The AI would interpret anything he said literally. “I want you to run a comparison,” he said. “Have we ever seen a Killer starship in a system that lacks a gas giant?”
There was another pause. “No,” Cromwell said, finally. The AI seemed to hesitate. “I must point out, however, that we have been unable to track all known Killer vessels for long periods of time and they might well have visited systems without gas giants.”
“True,” Brent agreed, although he was convinced that he’d made an important discovery. “All of the attacked star systems, all of the Killed star systems, do they have gas giants as well?”
“Negative,” the AI said. “Seventeen dead worlds were located in systems that do not possess a gas giant.”
“Our worlds,” Brent corrected, impatiently. “Did we ever lose a system that lacked a gas giant?”
“No,” Cromwell said. “All attacked human star systems included at least two gas giants. Do you believe that that provided a motivation for the attacks?”
“I don’t know,” Brent admitted. “I just don’t know.”
He looked down at the display, watching the Killer star systems slowly spinning around the galactic core. Human scouts had confirmed that there was a massive black hole right at the heart of the galaxy and, eventually, it would devour the entire Milky Way. If the human race was still around, billions of years in the future, they might have to flee the galaxy completely, or perhaps… by then they might have mastered technology they could use to control or seal the black hole.