Root of Unity (3 page)

“I’ll go by your house in a few hours with some equipment,” said Arthur. “And then we’ll come back and look at your office again. Don’t handle nothing you ain’t touched already.”

Halliday made an abortive gesture at the books and papers surrounding her. “I have to…my work—”

“Can wait,” Arthur said.

“He’s right,” I put in. “Take the day off, go have a stiff drink or three. We’ll call you.”

“I don’t drink.”

Of course she didn’t. “Then sit in a park and read some combinatorics papers or something. What else do people do to relax?” I asked Arthur.

He gave me a funny look, but addressed Professor Halliday instead. “Sonya, she’s right. Go get some coffee; try to stay calm. We’ll figure this out.”

“Things don’t always work out, Arthur. You should know that better than anyone.”

Arthur didn’t reply, though his movements hitched for a second before he became the supportive friend once more, nudging Halliday gently to her feet. “Give me your keys, okay, hon? We’ll call in a bit.”

She obeyed, and Arthur guided us out of her office and locked the door.

“You going to be okay?” Arthur asked.

She hesitated. “My biggest fear is—I don’t know if I can recreate it. My greatest achievement, and I don’t even know…what if it’s gone?”

Arthur took her by the shoulders. “Ain’t gonna make you no promises I can’t keep. But Russell here is the best there is, and I ain’t too shabby myself. Take this one day at a time, okay? We’ll call.”

She nodded.

“Come on. We’ve got a lot of work to do,” I prodded Arthur.

He squeezed Halliday’s shoulders one last time. As we headed off at a trot, he glanced back several times to where she stood thin and bereft in the hallway.

Well, this sucked for Arthur. Of course, that didn’t mean I wasn’t going to take his head off the moment we were out of sight.

Chapter 3

In the end,
I was very well-behaved. I waited until we were in the car. Arthur was pulling out of the visitor’s parking lot and had the gall to say to me grimly, “So, I get this is a big deal. Can you give me the layman’s rundown?”

“You first,” I said. Penguins could have gotten frostbite from me.

He hesitated. “Me first what?”

“Fuck you,” I said, though I couldn’t force as much vitriol into it as I wanted. “The client will pay my rates?”

“You’ll be paid—”

“She didn’t want me there. She didn’t even want
you
there.”

“She came around, though, right? I knew she’d let us help if—”

“You lied to me.”

“Okay, yeah, but I didn’t know if—”

“If what?” I bit out. “If I’d come along if you weren’t paying me to?”

“You got to understand—she’s too important to me. I didn’t mean—I needed you; I ain’t thought—”

“You thought if you said, ‘hey, Cas, help me out,’ that—what, I’d say
no?”
Voicing the words stung. I bit my lip.

“Well, to be fair, money’s what you always—and you can’t be too hard on me, Russell, if this ain’t no official job for you, can you take it anyway?”

It was a fair concern. After all, Arthur knew what happened when I wasn’t working—he was one of the few. That didn’t mean I wanted to concede. “You could have asked me. For the record, I’ll be
fine.”

“I’m sorry,” he said, though I didn’t hear much repentance in his tone. “It was too important; can you understand? Please? But I’m sorry. I am.”

“So who is she?”

He took a long breath. “Sonya and I—we grew up together. Childhood friends.”

“And then?”

“And then what? Life happened. We grew apart. Ain’t mean I don’t still care about her.” He kept his eyes glued to the road in front of him, like someone who wasn’t telling me anything close to the whole story. “So, uh. This math stuff. Help an old guy out—why is the world ending?”

“This isn’t over,” I grumped, but I let him change the subject. For now. I slumped in the passenger seat, sticking my boots up on the dash. “Do you know anything about encryption?”

“Not a thing.”

“Okay. Well, a whole hell of a lot of our current crypto depends on the idea that factoring large integers is a really hard problem. In simple terms, we encrypt information by multiplying large prime numbers together, and the fact that no one can
un-
multiply them easily is what keeps everything secure. And ‘everything’ means everything—from your credit cards to the Department of Defense.”

Arthur let out a low whistle.

“Yeah,” I said.

“So Sonya cracked the crypto?”

“Sort of,” I said. “The ticket is, we’ve always
thought
factorization was a hard problem, but we’ve never actually known it was hard. Nobody’d ever proven it was.”

Arthur frowned. “Why’s everyone use it, then? Seems kind of unwise.”

“Not that unwise. A lot of really smart people had been working on the problem of integer factorization for a very long time, and nobody’d come up with a fast way of doing it. Key word being ‘fast’—we
can
do it; it just takes years, far too long to be useful in code-breaking. So building an encryption algorithm based on the fact that nobody’d ever discovered a way to do this quickly, well, it was actually pretty genius.”

“Except Sonya found a way,” said Arthur.

“Yeah.” I still couldn’t believe it. As grave as the situation was, part of me was ravenous just to read her proof. “Yeah, she thinks she did.”

“And you say everything runs on this math.”

“Yeah. Checker might know better than I would where all it’s being used, but I’m pretty sure it’s across the board. Every financial transaction people send electronically. Our whole economy, national security, all of it.”

“Jesus, Mary, and Joseph,” whispered Arthur. “So if whoever got her proof decides they’re bored just making themselves rich…”

“Modern apocalypse,” I said. “It’s possible. I think we’ve got a little breathing room, though. Professor Halliday said she was in the midst of going back through decades of notes and rewriting the proof for publication—it’ll take them time to organize and absorb all her work. And they’ll probably need someone in the field to help them with it. Plus they’ll have to write whatever actual computer code they want to use—I’ll have to talk to Checker and see if he can estimate how long that’ll take—”

“Wait,” said Arthur. “Did you just say they’d need a mathematician even if they have her notes?”

“Yeah,” I said. “Probably more than one.”

“
Shit,”
said Arthur, yanking the wheel to slue the car toward the next exit, “Sonya—she ain’t safe—”

A car slammed into us from behind.

Metal shrieked and the seatbelt wrenched me across the chest. The car spun more than 180 degrees and slid into a skid across four lanes of freeway, traffic screeching by us the wrong way around—

I reached for the wheel and yanked it over, Newtonian mechanics erupting in my brain like a fountain. “Accelerate!” I bellowed in Arthur’s ear; he immediately let go with his hands and slammed his foot down on the pedal.

“Switch with me!” I shouted, diving for my seatbelt release with my other hand and cursing Arthur’s insistence that I wear it. Horns deafened the air in a cacophony around us, and a screeching crash blasted through the noise as if it were right next to my ear—two cars avoiding us had smashed into each other and one had flipped over the median. I swung the wheel the other way with a solid wallop of inertia, sending us barreling between a semi and a minivan as I brought us out of the skid. The minivan’s driver jerked away, and it turned directly into the path of a bright blue sports car. I could have screamed—not that you could have heard it over the deafening explosion of metal and kinetic energy. “I wasn’t going to hit you!” I yelled in pure frustration.

I got my foot down on top of Arthur’s, and he tried to get out from behind me, but I just ended up sitting half on top of him. It would have to do. I glanced in the rear view mirror—it wasn’t hard to spot the car that had nailed us. A black SUV with its front end smashed in careened dementedly through traffic, a deranged monster set on plowing through anything to get to its prey.

“Hang on!” I shouted.

Possibilities. Probabilities.

The quickest way to lose them would be to leap the cement median—nothing to it, just hit the correct angle, bam—and zip down the busy freeway in the opposite direction. We’d get away free and clear, but I knew from experience that a lot of drivers would spin out of control trying to avoid me, completely ignorant of the fact that I was perfectly well able to avoid them. I might not lose sleep over the collateral damage, but Arthur was in the car, and he definitely would.

If I was looking for as few civilian casualties as possible, that meant getting off the freeway
now.

I glanced to the right, the cars overtaken in my vision by their velocity vectors, arrows of speed screaming down the lanes. I yanked the emergency brake to lock us up and spun the wheel, sending the car into a sideways skid again across three lanes of full-speed traffic like we were Super Frogger, the cars just missing us as they zipped by. Horns blared, but I didn’t hear any other crashes. I whipped the wheel the other way to seesaw Arthur’s sedan onto the exit ramp, my mind already racing ahead. The freeway had been okay, but LA traffic isn’t a possibility; it’s an inevitability. Once I hit the streets I might have a parking lot to deal with.

I glanced in the rear view again. The SUV was swerving onto the ramp after us, and someone was leaning out the window with, of all things, a grenade launcher.

What. The. Fuck.

Options, options—where were we in the city? I hadn’t been paying much attention, but I briefly remembered seeing signs for the 5…

The river. We could make it to the river.

We hit the end of the exit ramp and I aimed for the edge of the road, thanking fate that Arthur had been driving an older tank of a sedan. I wrenched the wheel as I felt the jaw-jolting bump of the curb and spun us up on two wheels, slamming the car onto its left side as we slued around the backlog at the end of the ramp and onto the street. It was jammed, as expected, but we flew through the intersection and I pointed the car at the sidewalk, our right two wheels walloping down onto it so we were straddling the curb. Arthur grunted behind me and people screamed outside. I laid on the horn and popped the accelerator to jump the curb completely and come off the road into a car park.

We were in some sort of industrial area. I zigged through the rows of parked vehicles trying to get us westward—it couldn’t be far now. Another glance at the mirror showed the SUV had been slowed by the intersection, but it was still dogging us, their gunner trying to line up a shot with the
freaking grenade launcher—

I hit a bank of railroad tracks and we thumped over them, the sedan almost shaking loose from its frame, and then the river was ahead.

During summer, the Los Angeles River can only be called that charitably. In the midst of the high heat it’s a trickle of water through a wide, high-walled concrete ditch; instead of a river it looks more like something that was built for an industrial park to keep a thin stream of toxic waste away from contaminating anything.

I jammed my foot down on the gas pedal until it hit the floor, and we sailed off the high bank of the concrete trench. The car’s wheels spun uselessly in the moment of weightlessness before gravity took hold, and then we belly-flopped on all four wheels into the bare cement at the bottom of the channel.

I’d been running stress calculations, but there was some guesswork here. I didn’t know enough about Arthur’s car, and it wasn’t as if I could stop to look under the hood. Fortunately, the tough beast of a sedan took off like a shot, and I floored it northward along the river. I was still half-pressed against Arthur behind me; I could feel him shifting and struggling to hang on.

Behind us, the SUV flew out onto the edge, and couldn’t stop in time. Whoever was at the wheel made the idiot decision of trying to brake, and the ponderous vehicle flipped up over into a nosedive and plunged headfirst into very unforgiving cement.

The person with the grenade launcher must have thought fast—about to die a flesh-crunching death, he still managed to aim and pull the trigger.

Grenades aren’t quite as fast as bullets. I had a precious millisecond to see just how it was going to impact us. I saw the explosion, shock waves, concussion, outlined in concentric circles of force like it was a diagram on a map of the impact. I saw the overlapping patterns of death depending on what type of grenade it was, and how far we would have to move to be outside the radius of danger.

Saw the infinite options of how I could move the car in the split second I had, and that none of them would be enough.

I jerked the wheel one last time and bounced us into the wall of the concrete channel. And then fell as the car flipped.

Metal screamed and glass shattered as the car skidded up onto its left side and screeched down the riverbed. I clung to the steering column like a monkey to avoid being scraped off with the side panels; behind me, Arthur jammed his fists against the roof.

The grenade hit.

I’d mooned it with the bottom of the car to protect us. The impact exploded against the river wall and the concussion cannonballed into our undercarriage—

—with way, way,
way
more force than I’d anticipated. Even with the most generous estimates. Even for a high-explosive round.

The shape of the blast imprinted itself mathematically in my brain as it clipped the sedan and slammed us into a barrel roll. But the equations didn’t do me any good. I found fancy ways to obey the laws of physics; I couldn’t rewrite them.

A rolling car is sheer mass. So massive its momentum can’t be stopped, so massive the force of gravity smashes it into the earth like a rag doll, so massive that a person, no matter how strong or skilled or mathematically-knowledgeable—a person couldn’t stop it. The sides and top of the car imploded alternately as we crashed into the concrete again and again, and there was nothing I could do. I tried to brace myself but only managed a local optimum—I saved myself from being crushed to death but didn’t avoid a three-hundred-sixty degree beating by twisting, reaching metal.