"Go on," Martin said.
"Radiation flux from the planets does not exceed expected natural levels. Both rocky inner worlds are either dead, or quiescent, pointing perhaps to a solid-state civilization, that is, all activity confined to information transfer through quiet links, or using noach, as we do."
"No physical bodies? Nothing organic?" Martin asked.
"None visible. If there are organics below the surface, they produce no traces on the surface itself, and that is odd. At this distance we might miss extremely light organic activity, but judging from the telescope images… Here." He pulled up a projection. Smiled at Martin as the image wavered. "My wand works overtime. Thorkild, clear some capacity, please, or shunt it to the moms' systems!"
Thorkild looked up, lost in momerath and graphics. A few of the stacks dimmed or winked out.
The second planet rotated once every three hundred and two hours, surface temperature of one hundred and seventy degrees Celsius, albedo of point seven, light gray and tan, no oceans of course, thin atmosphere mostly carbon dioxide and nitrogen, no oxygen, no geological activity, mountain chains old and worn with no young replacements, no visible structures over a hundred meters in size. Or no structures with a height of more than ten meters…
"All right," Martin said, deliberately quelling his enthusiasm. "Both inner planets are quiet."
"In keeping with the biblical turn of phrase," Hakim said, "I suggest we call the inner planet Nebuchadnezzar, the second Ramses, and the third, Herod."
Martin made a face. "Might be a bit prejudicial, don't you think?"
"Mere suggestion," Hakim said. His face brightened. "Ah, yes, I see what you are getting at. Herod destroying the first born… Ramses overseeing the captivity of the Jews. Nebuchadnezzar having destroyed the first temple in Jerusalem… I see."
"The names are fine," Martin said.
"Good." Hakim seemed pleased. "Ramses… the next rocky planet, second planet out, is like this…" He drew forth another chart, put it through its paces. "Similar to the first, but cooler—minus four degrees Celsius average temperature, albedo of point seven, atmosphere again contains no oxygen or water vapor. No seismic activity, old mountains—old worlds."
"They might be deserted."
"We do not think so. The strongest evidence of continuing artifice lies in their temperatures versus their distances from Wormwood, and their atmospheric compositions. They are actively controlled environments, but for what sort of organisms or mechanisms—if any—I cannot say."
"Very small machines," Martin mused.
Hakim nodded. "That is difficult to confirm, of course. If they exist, their work is isolated from the surface."
"But the worlds areactive."
"Active, yes, but they do not have large numbers of physical inhabitants—living creatures. The moms teach us that many civilizations reduce their presence to information matrices, abandoning their physical forms, and living as pure mentality."
"About half of all advanced civilizations…" Martin remembered, stroking his cheek with one hand.
"Yes. That could be the case here."
Maybe they've become ghosts. Martin shuddered at the thought of abandoning physical form; like spending forever in neural simulation. What would they gain? A low profile, a kind of immortality—but no need to physically colonize the systems they "sterilized" for future use. "You said we could almost make a judgment."
Hakim's face brightened. "I have been teasing, Martin. Withholding the best until last. This is very good. But you judge."
He ordered a series of charts on debris scattered throughout the ecliptic between fifty million kilometers and seven hundred million kilometers from Wormwood. "Dust and larger particles heated by the star, chemical reactions excited by the little stellar wind that does get through… Very interesting."
The dust and debris pointed to intense spaceborne industrial activity in the system's past. Much of the debris consisted of simple waste—rocky materials, lacking all metals and volatiles, heavy on silicates.
Manufacturing dust from shaping and processing: trace elements inevitably mixed into the dust, reflecting even more precisely than in the spectrum of Wormwood itself the proportions of trace elements in the killer machines.
"It's more than a close match," Martin said.
Hakim revealed his excitement in a mild lift of eyebrow.
"It's exact," Martin said.
"Very nearly," Hakim said.
"They made the killer machines around Wormwood."
"Perhaps around Leviathan, as well. We are not close enough to judge."
"But certainly here."
"The evidence is compelling."
Martin's skin warmed and his eyes grew moist, a response he had seldom felt before, and could not ascribe to any particular emotion. Perhaps it came from a complex of emotions so deeply buried he did not experience them consciously.
"No defenses?"
"None," Hakim said. "No evidence of defenses on the surface of the inner worlds. The depleted gas giant shows even less activity, a large lump of cold wastes and rocky debris, with a thin atmosphere of helium, carbon dioxide solids, bromine, and sparse hydrocarbons. Here is a list."
"Where did the volatiles go?" Martin asked. The list was devoid of hydrogen, methane, and ammonia. The thin haze of helium was so diffuse as to be useless. No swooping down to scoop up fuel, like Robin Hood swinging out of a tree to snatch a purse.
"Good question, but I can only guess, the same as you. The star is well over six billion years old. The volatiles could have been lost during birth, with the cold outer worlds getting correspondingly thinner envelopes of atmosphere. But this would be unusual for a yellow dwarf in this neighborhood."
"Even in a multiple group?"
Hakim nodded. "Even so. The volatiles might have fueled early interstellar travel within the group. The pre-birth cloud is also very low on volatiles, remember. Or…"
Martin looked up.
"Most of it could have been converted to anti em for making killer probes."
"That's a lot of probes," Martin said.
Hakim agreed. "Billions, fueled and sent out across the stellar neighborhood. Depleting the outer cloud, the comets, the ice moons, the gas giant, everything… If I may say so, a massive and vicious campaign with great risks, at great expense. To be followed logically by a wave of stellar exploration and colonization."
"But we don't see any settled systems beyond the group… It wouldn't make sense to launch such a campaign, and not follow through."
"Ah." Hakim raised his finger. "Centuries must pass while they wait for the probes to do their work. What if the civilization changes in that time?"
"Seems certain they'd change some," Martin agreed.
"A change of heart, perhaps, or sudden fear of the wrath of other civilizations. Cowardice. Many possibilities."
"What percentage of converted volatiles could be stored in the five masses?"
"A minuscule amount of the total estimated gases lost from the system," Hakim said. "We're not yet certain of the size, but each of the masses appears to be several thousand kilometers in diameter, which would rule out neutronium, if their densities were uniform."