Charles Stross - Singularity Sky

And why I need your help. I wouldn’t normally dump this on you, but I really need your help, active help, in figuring out what’s going on. Do you understand?”

“I understand very little,” Martin said nervously, priming his autonomic override to keep his pulse steady so as not to betray the lie. He felt unaccountably guilty about withholding the truth from her. Rachel seemed like the least likely person to jeopardize his mission — and he liked her, wanted to be able to relax in her presence freely, without worries. But caution and experience conspired to seal his lips. “I’m just along for the ride,” he added. He simply couldn’t tell her about Herman. Without knowing how she’d react, the consequences might be disastrous. Might. And it was a risk he dared not take.

“Understand this,” she said quietly. “A lot of lives are at stake. Not just mine, or yours, or this ship’s, but just about everyone within a thirty-light-year radius of here. That’s a lot of people.”

“Why do you think this is going to drag the big E into the situation?” he prompted. He was deathly tired and didn’t want to have to lie to her. Can I keep her talking ? he wondered. If she didn’t keep speaking, he was afraid he might tell her too much. Which would be a big mistake.

She touched his arm. “The Eschaton will be interested for a simple reason; it is absolutely opposed to causality violation. Please don’t pretend you’re that naive, Martin. I’ve seen your resume. I know where you’ve been and what you’ve done. You’re not an idiot, and you know what a well-tuned warp drive can do in the hands of an expert. In terms of special relativity, being able to travel faster than light is effectively equivalent to time travel — at least from the perspective of observers in different frames of reference. They see the light from your arrival, which is close to them, a long time before they see the light from your departure, which is a long way away. Because you’re outrunning the speed of light, events appear to happen out of sequence. Okay? Same with a causal link, an instantaneous quantum-entanglement communicator. It doesn’t mean there’s real time travel involved, or that you can create temporal paradoxes, but being able to mess with an observer’s view of events at a distance is a boon for strategists.

“The Eschaton doesn’t care about such trivial kinds of time travel, but it stamps hard on the real thing; any manifestation of closed timelike paths that could jeopardize its own history. The big E doesn’t want anyone doing a knight’s move on it, back in time and then forward again, to screw over its origin.

Someone tries to build an instantaneous communicator? No problem. They go on to build a logic gate that transmits its output into its own past, where it’s wired into the input? That’s the basis of acausal logic, and it gives you the first tool you need to build a transcendent artificial intelligence. Poof, the planet is bombarded from orbit with cannibal lemmings or bitten to death by killer asteroids or something.

“Anyway, I don’t really care all that much what the New Republic does to the Festival. I mean, maybe I care about individual people in the New Republic, and maybe the Festival folks are really nice, but that’s not the point. But I do care if they do whatever they’re going to do inside Earth’s light cone. If it involves large-scale causality violation, the E might decide to take out the entire contaminated zone. And we know it seeded colonies as much as three thousand light-years away— even assuming it still wants humans around, it can afford to wipe out a couple of hundred planets.” Martin had to bite his cheek to keep from correcting her. She fell silent. He waited for her to continue, but she didn’t; she seemed almost depressed,

“You have a lot of clout. Have you told them what you’ve deduced? Or told anybody else?” She chuckled, a peculiarly grim laugh. “If I did that, how long do you think it would be before they chucked me overboard, with or without a vacsuit? They’re paranoid enough already; they think there’s a spy on board, and they’re afraid of minelayers and saboteurs along the way.”

“A spy ?” He sat up, scared. “They know there’s a—”

“Be quiet. Yes, a spy. Not one of us; some goon from the Curator’s Office who they sent along to keep an eye on you. Be quiet, I said. He’s just a kid, some wet-behind-the-ears trainee cop. Try to relax around him. As far as you’re concerned, you’re allowed to talk to me; I’m the nearest representative of your government.”

“When are we going to get off this ship?” he asked tensely.

“Probably when we arrive.” She took his hand and squeezed it. “Do your job and keep your head down,” she said calmly. “Just don’t, whatever you do, act guilty or confess to anything. Trust me, Martin, like I told you before: we’re on the same team for the duration.” Martin leaned close to her. She was tense, very tense. “This is quite insane,” he said very slowly and carefully as he slid an arm around her shoulders. “This idiotic expedition is probably going to get us both killed.”

“Maybe.” Her grip tightened on his hand.

“Better not,” he said tightly. “I haven’t had a chance to get to know you yet.”

“Me neither.” Her grip relaxed a little. “Is that what you’d like to do? Really?”

“Well.” He leaned back against the hard wall beside the bunk. “I hadn’t thought about it a lot,” he mused,

“but I’ve been alone for a long time. Really. Before this job. I need—” He shut his eyes. “Shit. What I mean to say is, I need to get out of this job for a while. I want a year or two off, to pull myself together and find out who I am again. A change and a rest. And if you’re thinking about that, too, then—”

“You sound overworked.” She shivered. “Someone just walked over my grave. You and me both, Martin, you and me both. Something about the New Republic uses you up, doesn’t it? Listen, I’ve got about two years’ accumulated leave waiting for me, after I get home. If you want to go somewhere together, to get away from all this—”

“Sounds good to me,” he said quietly. “But right now …” He trailed off, with a glance at the cabin door.

There was a moment’s frozen silence: “I won’t let you down,” she said softly. She hugged him briefly, then let go and stood up. “You’re right. I really shouldn’t be here, I’ve got a room to go to, and if they’re still watching me — well.”

She took her cap from the upper bunk, carefully placed it on her head, and opened the door. She looked back at him and, for a moment, he thought about asking her to stay, even thought about telling her everything; but then she was gone, out into the red-lit passages of the sleeping ship.

“Damn,” he said softly, watching the door in mild disbelief. “Too late, too late. Damn …”

The shooting began with a telegram.

Locked in a loose formation with six other capital ships, the Lord Vanek hurtled toward the heliopause, where the solar wind met the hard vacuum of interstellar space. Wolf Depository lay five light-years ahead, and almost five years in the future — for the plan was that fleet would follow a partially closed timelike path, plunging deep into the future (staying within the scope of a light cone with its apex drawn on New Prague at the time of first warning of attack), then use the black boxes attached to their drive modules to loop back into the past. Without quite breaking the letter of the Eschaton’s law— Thou shalt not globally violate causality —the fleet would arrive in orbit around Rochard’s World just after the onslaught of the Festival, far faster than such a task force would normally cover the eight hops separating them from the colony world. In the process, it would loop around any forces sent by the enemy to intercept a straightforward counter-strike — and pick up a time capsule containing analyses of the battle written by future historians, the better to aid the Admiral’s planning.