Yu nodded. “(I believe so.)”
“What’s the result?” called Ruszek, whose back was to them.
“Excellent,” Yu replied. “I think once I have analyzed these readings, with Esther’s help, I will know how the field drive operates.”
“You don’t? I mean, uh, you told me before, you’re sure it’s a push against the vacuum.”
Yu sighed. “An interaction with the virtual particles of the vacuum,” she corrected. “Energy and momentum are conserved, but, loosely speaking, the reaction is against the mass of the entire universe, and approximately uniform. What I referred to was understanding the exact, not the general, principle.”
“Uniform? Don’t they adjust the field inside a hull? Weight’s the same during any boost.”
“In quantum increments, obviously.” Yu paused. “Compared to this drive, jets are as wasteful as … as burning petroleum, chemical feedstock, for fuel once was on Earth.”
“What I like is the handling qualities. How soon can you and your computer design a motor for us, Wenji?”
“Not at all, I fear, until we’re home. Besides, we couldn’t possibly do so radical a retrofit on Envoy, or even her boats.” Yu’s voice lilted. “However, I think, with Hanny’s help when she gets back, we can devise a unit that will compensate for linear acceleration and keep the vector in the wheels constant.”
“Do you mean, when the ship’s under boost, we won’t have to cram like swine onto those manhater-designed gimbal decks?” Ruszek waved clasped hands above his shining pate. “Huzzah!” he bellowed.
Esther looked at ens friend. “(Does he rejoice?)” en asked; or so Yu thought en asked.
“(It is no large matter,)” the engineer replied. “(What I think we have really done, at last, is break some dams of misunderstanding. Now you and I can add a proper language of physics to Cambiante, and have it ready for Hanny Dayan when she returns. Before then, you should be able to explain some things to us. Hints of a strange, tremendous truth — )”
Her gaze went ahead, to the planet, where spring was gusting over Terralina.
Envoy rode as at anchor, circling a world of steel.
Cleland and Kilbirnie stood before the spaceview on a screen. Already their shipmates were busy. Robots would flit out to place instruments in orbit; Tahirian probes with Tahirian field drives would plunge toward the pulsar, wildly accelerated, bearing other instruments; preparations filled every waking hour and haunted many dreams. These two alone had little to contribute. Their yearnings reached elsewhere.
In the light from the heavens, the globe was barely bright enough for the unaided eye to search. Its plains were like vast, murky mirrors, mottled with ice fields. Gashes broke them here and there. Mountain ranges and isolated peaks thrust raw-edged. The limb arched slightly blurred against the stars.
“Mass about half Earth’s, diameter about seventy percent — given the mean density, more or less the same surface gravity.” Cleland was repeating what they had both heard a dozen times, as humans will when the matter is important. “Thin atmosphere, mostly neon, some hydrogen and helium retained at this temperature. Other volatiles frozen out, including water. Paradox, paradox. What’s the answer?”
“What do you mean, Tim?” Kilbirnie asked. It was chiefly to encourage him — she had a fairly good idea — but she hoped for thoughts he might have had since the last general discussion. God is in the details, she reflected. And so is the devil, and the truth somewhere in between.
When he was into an enthusiasm he spoke fluently. “Look, we know this has to be the remnant of a bigger planet. The supernova vaporized the crust and mantle, left just the core and maybe not all of that. The loss of star mass caused it to spiral out into this crazy orbit it’s got now. Meanwhile, taking off the upper layers released pressures — expansion, eruption, all hell run loose. It hasn’t stabilized yet, I suspect. What’s going on? Theoretically, it should be a smooth ball, but nonlinear processes don’t pay much attention to theory, and so we’ve got rifts, grabens, highlands. How? Where did it get the atmosphere and ice — outgassing, cometary impacts, infall from the supernova cloud, or what? Oh, Jean, a million questions!”