Nightside City

Chapter Twelve

DEPENDING ON WHAT YOU KNOW ABOUT EPIMETHEUS and planetology in general, you may be wondering either why I wanted to shoot her, or, if you're a little more up on the subject, why I didn't shoot her. I'll take the second question first.

I didn't shoot her because I knew that if I did, I would never make it out of the city alive. I probably wouldn't make it out of the house alive. And the idiots at the Ipsy might just be dumb enough to go on without her. I needed a less direct approach.

As for why she deserved to be shot, just think about it for a minute.

Epimetheus is about 9,056 kilometers in diameter, with a density of seven grams per cubic centimeter. A rough calculation on a unit in my head gave me a figure of twenty-six times ten to the twentieth tons for the total mass, but I probably messed that up somewhere. In any case, we're talking about trillions of tons of mass. We're talking about a very thin crust that's rotating at 138 centimeters a day at the city's latitude.

Now, I admit, that's not very fast. If you were in a cab moving that fast, and it hit a stone wall and stopped instantly, you could probably just step out unhurt. The cab would probably be unhurt. But a cab is a solid piece of fibers and ceramics, designed to take a lot of stress and with a mass of maybe half a ton. A planet's a dynamic system, and there's just so much of it.

Let's suppose that they set off a charge designed to exactly counter the momentum of the planet's rotation-exactly the right amount of energy. Where are they setting this charge off?

On the surface, presumably, or just below.

You think it's going to stop the core? Or the mantle, which isn't even completely solid to begin with?

Hell, no; the crust is going to rip itself loose from the mantle and probably come apart completely. The crust is already pretty thin and delicate on Epimetheus, with volcanoes scattered all along a million fault lines; where most planets have maybe a couple of dozen continental plates, Epimetheus, because of its hot interior, has thousands.

If you wanted to stop the planet from rotating, first you'd have to fasten it all together with something a bit stronger than the hot rock and gravity it has naturally. As it is, a big shaped fusion charge is just going to ram one or two plates back against the others and tear a big hole in the crust-if you're lucky.

More likely it would just vaporize a piece of crust. I've never heard that shaped fusion charges are all that reliable to begin with.

And then there's the meltdown factor.

Let's consider that charge again. It's putting out one hell of a lot of energy, very quickly. Theoretically, most of that's going to be kinetic energy, directed against the planetary rotation. Some of it is going to be light and heat, though; a lot of heat.

And that kinetic energy is bumping right up against the kinetic energy the planet's already got. When you run those together, they don't cancel out; there's this little detail called the law of conservation of energy, which I know doesn't always apply, but it's still a good rule of thumb when you're working with large-scale, low-energy, normal-space systems like planetary surfaces. If the two kinetic energies are perfectly matched, the two moving masses do stop, all right, but the energy doesn't disappear. It just changes form. In this particular example, it mostly changes to heat.

So you've just added who knows how much heat energy to Epimetheus, which is already a very young, hot, and radioactive planet, which is why the nightside is habitable.

Epimetheus is Eta Cass A III. Ever hear of Eta Cass A II? They never agreed on a name for it, because the obvious one, Vulcan, was taken. I grew up calling it Cass II.

It's molten. And that's not because of its proximity to the sun, either. It's a runaway fission reactor. While it was still liquid, still forming, enough of the radioactives settled down to the core to reach critical concentration. It wasn't enough to go bang, but the chain reactions are still going strong, and that whole planet's going to stay molten for a long, long time yet. Not to mention all those unhealthy fission products-though I suppose most of them never reach the surface.

You add enough heat to Epimetheus, and it might melt down, too. Hell, the planet's laced with uranium and thorium and other radioactives-that's why they mine it. A little added heat and motion would stir those radioactives up; because they're heavy, they're already settling down through the mantle toward the core and collecting there. Add heat, and you'll speed that up, at the very least. You'll be adding energy to an unstable system, and you might just be accumulating critical mass in the core, and the whole damn thing could wind up as radioactive slag.

Now, I don't know that Nakada's one big charge would do that, would trigger a meltdown, but I sure as hell didn't want to find out by experiment. Quakes and volcanoes were the least we could expect.

And that idiot didn't seem to see any of this.

I wasn't sure what to make of that. Sure, she'd grown up on Prometheus, where the crust is thicker and more stable and there aren't any peculiarities to the planetary rotation, but hadn't she studied up on Epimetheus before she bought into the scheme? Even if she was too lazy to jack the data in on the conscious level, she could afford the best and fastest imprinting on the planet.

Was it just that she wanted the scheme to work, the way her ventures in genens and psychobugs hadn't? I knew she was good at ignoring unpleasant details, but could she really ignore all the dangers?

Maybe, subconsciously, she wasn't ignoring them at all. Maybe she intended to watch from orbit, so she'd live through it, and she didn't really care if it failed. She'd shown enough of a self-destructive streak before to make that believable. Maybe she wanted to gamble, and wanted to watch all the fireworks when she lost.

After all, she probably had a grudge against the entire planet. Epimetheus wasn't her home, it was her exile. Wrecking an entire planet would certainly be a grandiose enough way of expressing her annoyance at being exiled.

I mean, I'm sure she wasn't thinking that consciously, or at least I hope she wasn't, but in her subconscious she must still have been the spoiled kid she'd been twenty years earlier on Prometheus. So after some thought I could maybe see how Nakada could be going ahead with this idiot scheme.

But that didn't explain what the people at the Ipsy thought they were doing.

Maybe there was more to this than I knew, I thought. Maybe I'd misunderstood the whole thing, or Nakada had misunderstood the whole thing and passed it on to me. Maybe what the Ipsy really had in mind was using a fusion charge to plow Nightside City's continental plate back onto the nightside, like an icebreaker in one of those old vids from Ember-but that could be pretty rough, too.

Maybe they had safety precautions. Maybe they had some way of dissipating the heat, or holding the crust together. Maybe they were going to get a charge down into the core somehow and do something there.

Because there was one thing more that Sayuri Nakada didn't seem to realize. If you could somehow stop Epimetheus right where it was-without breaking anything, without so much as spilling anyone's tea-you still wouldn't have saved Nightside City for good. There's a reason that the planet's rotation is screwed up. That core is still off-center, and sooner or later it's going to pull around so that the thin side of the mantle is facing directly toward Eta Cass A. If you stopped the planetary rotation where it is now, eventually it would start up again-not so much a rotation as a wobble.

Wouldn't it?

I realized that I didn't know, and that I had no way to find out while I was walking the streets of the eastern burbs.

Even if the planet did start to swing around again, how long would it take? Planets have one hell of a lot of inertia. They're slow. It might be millennia before the city started moving again. In fact, the more I thought about it, the more likely that seemed, so that renewed rotation wouldn't really be a problem after all.

Would it?

This was all too complicated for me. I wasn't a planetologist. I wasn't a physicist. I didn't even know enough to go back and try to argue with Nakada. I had to learn more.

Well, I was a detective. I was supposed to be good at learning things and putting them together.

I had two choices, as I saw it. I could go back home and plug myself in and study up on planetology and try to figure out what the hell Nakada and the Ipsy were really up to, then maybe go back and argue about it. Or I could go to the Ipsy and ask someone.

Judging by the reception my earlier call got, I'd have to go in person if I wanted answers out of the Ipsy. They didn't want to talk to me.

Well, on the com, you don't have to talk to anyone you don't want to, but it's harder to ignore someone who's actually physically there, right in front of you. It's harder to lie, too-holos and sims take advance preparation if they're going to be convincing seen directly, but they're pretty easy to improvise over a com line.

And it's hardest of all to ignore someone when she's standing there with a gun in your face. I hoped I wouldn't have to resort to that. It had worked so far, but sooner or later somebody might call my bluff-or call the cops.

And it was a bluff, all right; I wasn't ready to shoot an unarmed human. I'd have second thoughts even about software, usually-that would depend how advanced it was, how sentient, how strong its survival urge, and so forth. I'd shot the eye, but spy-eyes aren't really sentient, aren't really alive.

At least, most of them aren't, and I sure hoped the one I shot hadn't been. It had handled my threats calmly enough.

Maybe I could shoot a machine, but shooting a human -that was a bluff.

But the people at the Ipsy wouldn't need to know I was bluffing, and a gun's a lot more intimidating in person than over a com line.

The Ipsy was located near the Gate, of course, where they could send their people and machines out of the crater easily, and where incoming miners could drop off samples or news or anything else they thought the Ipsy might be interested enough in to pay a finder's fee on. I hadn't been there in years, and I'd seen plenty of my office lately; dropping by the Institute would make for a pleasant change of scene.

Besides, it's always quicker to ask someone who knows the answer than to figure something out for yourself.

That is, it's quicker if he's willing to tell you. I just had to make the people at the Ipsy willing.

That was where bluffing with the Sony-Remington came in.

I called a cab, and when it arrived I told it to take me to the Ipsy.