Cities in Flight

The City Fathers had been turned off, and Amalfi was ready to move a world.

The fact that the City Fathers could not be consulted—for the first time since the Epoch affair five centuries ago, when the whole city had been without power for a while—made the job more difficult than it needed to be, barring their conservatism. Tipping the planet, the crux of the job, was simple enough in essence; the city’s spin-dizzies could handle it. But the side effects of the medicine might easily prove to be worse than the disease.

The problem was seismological. Rapidly whirling objects have a way of being stubborn about changing their positions in space. If that energy were overcome, it would have to appear somewhere else—the most likely place being multiple earthquakes.

Too, very little could be anticipated about the gravities of the task. The planet’s revolution produced, as usual, a sizable magnetic field. Amalfi did not know how well that field would take to being tipped in the space-lattice which it distorted, nor just what would happen to He when the city’s spindizzies polarized the whole gravity field. During “moving day” the planet would be, in effect, without magnetic moment of its own, and since computation was a function of the City Fathers, there was no way of finding out where the energy would reappear, in what form, or at what intensity.

He broached the latter question to Hazleton. “If we were dealing with an ordinary problem, I’d say the energy would show up as velocity,” he pointed out. “In which case we’d be in for an involuntary junket. But this is no ordinary case. The mass involved is … well, it’s planetary, that’s all. What do you think, Mark?”

“I don’t know what to think,” Hazleton admitted. “The equations only give us general solutions, and only quanticised solutions at that—and this whole problem is a classical field problem. When we move the city, we change the magnetic moment of its component electrons; but the city itself is a low-mass body with no spin of its own, and doesn’t have a gross magnetic moment.”

“That’s what stuck me. I can’t cross over from probability into tensors any more than poor old Einstein could. As far as I know, nobody’s ever really faced up to the discontinuity between what the spindizzy does to the electron and what happens to a body of classical mass in a spindizzy field.”

“Still—we could control velocity, or even ignore it out here. Suppose the energy reappears as heat, instead? There’d be nothing left of He but a cloud of gas.”

Amalfi shook his head. “I think that’s a bogey. The gyroscopic resistance may show up as heat, sure, but not the magnetogravitic. I think we’d be safest to assume that it’ll appear as velocity, just as in ordinary flight. Use the standard transformation and see what you get.”

Hazleton bent over his slide rule, the sweat standing out along his forehead and above his mustache in great heavy droplets. Amalfi could understand the eagerness of the Hevians to get rid of the jungle and its eternal humidity. His own clothing, sparse though it was, had been sopping ever since the city had landed here.

“Well,” the city manager said finally, “unless I’ve made a mistake somewhere, the whole kit and kaboodle, the planet itself, will go shooting away from here at about twice the speed of light. That’s not too bad—just about coasting speed for us. We could always loop around and bring the planet back to its orbit.”

“Ah, but could we? Remember, we don’t control it! The vector appears automatically when we turn on the spindizzies. We don’t even know in which direction that arrow is going to point. The planet could throw itself into the sun within the first second as far as we know. We can’t predict the direction.”

“Yes, we can,” Hazleton objected. “Along the axis of spin, of course.”

“Cant? And torque?”

“No problem—no, yes, there is. I keep forgetting that we’re dealing with a planet instead of electrons.” He applied the slipstick again. “No soap. Too many substitutions. Can’t be answered in time without the City Fathers—and torque might hype the end-velocity substantially. But if we can figure a way to control the flight, it won’t matter in the end. Of course there’ll be perturbations of the other planets when this one goes massless, whether it actually moves or not—but nobody lives on them anyhow.”

“All right, Mark, go figure a control system. I’ll see what can be done on the geology end—”

The door slid back suddenly, and Amalfi looked back over his shoulder. It was Sergeant Anderson. The perimeter sergeant was usually blasé in the face of all possible wonders, unless they threatened the city. “What’s the matter?” Amalfi said, alarmed.