“That sword,” Bruno says. “Small gods, I've seen nothing like it in . . . in . . .” He doesn't know how long.
Seeing his face, Lyman pulls the sword once more from its slim leather scabbard, and passes a hand again through the empty space that is its blade. “This, Ako'i, is one of the old air foils. A stabbing weapon, real difficult to parry.”
“Indeed!” Bruno exclaims. “An interesting use of the technology. There are others like it, then?”
“A few,” Lyman says with a shrug. “Here and there. We hang onto them, of course, for their monetary value if nothing else. Whole kingdoms have traded hands in exchange for one. But it's a dueler's dream, almost a guaranteed kill. And more importantlike, it's a fine weapon to baffle these mirror-plated scullery maids. They've yet to work out any defense. Just jab, jab, jab 'em in the box, in the eyes, in the joints, and down they go. Almost as good as a blitterstaff. Would you like to hold it?”
“Later, if you please,” Radmer interjects. “I must get this man to Timoch as soon as possible.”
Lyman turns back to him, looking puzzled and disappointed. “You're not coming with us? We could be under the veils in three hours. Nell has a pot of stew cooking and everything.”
The ghost of a smile flickers across Radmer's face and then vanishes. “That sounds wonderful, Lyman. Really. But my mission is more urgent than you seem to imagine. In fact, to the extent that I still command any loyalty, I'll request that you and your men accompany us as far as the city gates.”
“Really! As far as that?” Lyman asks, cynically amused. “And when they skin us alive as bandits, what would you give us in return? We have, if you recall, just saved your life.”
At that Radmer really does smile, looking for once like the Conrad Mursk that Bruno remembers. “My friend, you may have saved more than that. History will be the judge, not I, but I suspect you've just saved the world.”
And so he has, in a manner of speaking, though it will bring as much sorrow as joy. But that, alas, is another tale altogether.
Appendix A.
In which an appendix is provided engineering issues
On the subject of his engines, Money Izolo waxed loquacious. “Deutrelium burns clean, sir—only charged particles are produced, so we can steer them out the back with electric fields. Meaning there's no radiation hazard to the crew, in theory. But there's impurities, yah? Teeny little bits of the ship that get mixed in with the fuel slurry. These cause side reactions, releasing stuff like high-energy neutrinos, which convert some fraction of the electrons in the exhaust plasma into pions, which are harder to stop. That's a problem, a danger, that never goes away. I could use a whole person full-time, just monitoring the pion flux.”
Conrad smirked. “A true pioneer, eh?”
But Money missed the pun and just looked at him blankly for a moment before continuing. “When we're nonpropulsive, the demands on the reactor will be a lot less, and a lot steadier. Lighting, heating, life support . . . Those are predictable loads. Still, data processing can take a lot of power when the hypercomputers get large enough. Working on a tough problem they can fill this whole wall, with the heat sinks glowing red from dissipated information, which is the same thing as heat. And we expend about one hundred watts continuously on waste management, mostly dust.”
Conrad's eyebrow went up. “Dust?”
“Yah, there are mechanical parts on this ship: fans, bearings, hinges, and seals. Stuff like that. It's all subject to mechanical wear. And the stuff that rubs off winds up mostly in the atmosphere, as a nanoparticle smog which settles out on surfaces. And to the extent that we have people onboard, out of fax storage, there are always shed skin cells, and hair, and what have you. People shed an incredible amount of mass over the course of a month. Almost half a kilogram per person, which is more than the weight of your hand. Yah, I know, it's disgusting.
“Anyways, the wellstone bucket-brigades that stuff to the nearest fax machine for disposal, but it takes a certain amount of energy and computing to do that, see? And inside the fax there's a sorting penalty. We're fighting entropy itself. To turn a kilogram of dust into a kilogram of buffer mass sorted by atomic number, you need as much energy as you'd get from burning a thousand birthday candles. On a planet, that process happens naturally, powered by sunlight, and the fact that it's wickedly inefficient doesn't matter. But here it's a part of our daily maintenance. Like holding back the tide with a mop.”
“I thought entropy always increased.”
“It does, yah. All you can do is push it off somewheres else. With enough energy, you can reduce it locally, but there's a larger increase in the rest of the universe. It has to be that way, right? Or else life and machinery wouldn't be possible at all. But entropy is the great bill collector; it always catches up, oozing around every barrier. It'll find us in the end.”
“How comforting.”
“Isn't it? And then there's the occasional juking maneuver—we'll be in Sol's Oort cloud for another thirty years, and later on we'll be in Barnard's for ten. Juking takes energy, and requires a minimum reactor temperature. But yah, I think most of that can be handled automatically.”
Conrad ran his hand along the wall, feeling the flat, smooth texture of the wellstone. He tried to imagine the electrical potentials in there, dancing as oversized pseudoatoms flexed their orbital “arms” to pass a dust grain along. “That's interesting about the sorting penalty,” he said. “I've never heard anything like that before.” Return to text.
astrogation issues
Said Robert M'Chunu on the subject of getting lost: “You remember the term ‘drunkard's walk'?”
“No,” Conrad answered.
“Really? I thought you were one of the navigators on Viridity. Drunkard's walk is where you get random, quantum-level noise on a rate sensor. This is inevitable; no sensor is free of it. So you've got multiple rate sensors, each with its own random noise. This is fortunately very small, but you add up your rates over time to get your orientation, and suddenly you're accumulating and then squaring those errors. So they grow exponentially. If we let ours drift for six months, then the orientation we compute is complete gibberish. Six months is a long time for a planetary voyage. A really long time. But out here, it's nothing.
“Our Cartesian location—the XYZ of it—is even worse, because there you're integrating from acceleration to velocity to position, which cubes your errors. Of course you can always get a fixed reference for orientation, from the stars themselves. There are bright ones, distant ones, with close to zero proper motion. They're fixed against the sky, even though we're moving very fast. Those make excellent references, and they keep our attitude numbers sane. Downrange velocity we can get from the reference pulsars, which are neutron stars with very precisely known rotation rates. They flash like beacons, and we can measure the Doppler shift to obtain a fairly accurate velocity.
“But cross-range, perpendicular to our direction of travel, our references are poorer, and our precision is a lot lower. Just about the only lateral references we have are Sol and Barnard themselves. We're running a straight-line course between them, so their proper motion should be zero. They shouldn't drift against the background stars, not at all. So we look for very tiny motions, and compensate when we see them. But even on a good day that leaves us with velocity errors of walking speed or higher. And those errors are integrated to get position. You see the problem? Garbage in, garbage-cubed out. That's navigation for you.” Return to text.