Theo's heart jumped. Of course, years ago, after young Helmut had mentioned a Glock 9-mm, Theo had looked for a picture of one on the Web. The boxy semiautomatic weapon now facing him was just such a handgun; its clip could hold up to fifteen rounds.

The man looked down at the pistol, as if he himself was surprised to see it in his hand. Then he shrugged slightly. "A little something I picked up in the States-they're so much easier to come by over there." He paused. "And, yes, I know what you're thinking." He gestured at the aluminum suitcase with the blue LED timer. "You're thinking maybe that's a bomb. And that's precisely what it is. I could have planted it anywhere, I imagine, but I came a ways along the tunnel looking for a place to secrete it, lest someone find it. Inside this machine here seemed like a suitable spot."

"What-" Theo was surprised at how his voice sounded. He swallowed, trying to get it back under control. "What are you trying to accomplish?"

The man shrugged again. "It should be obvious. I'm trying to sabotage your particle accelerator."

"But why?"

He gestured at Theo with the gun. "You don't recognize me, do you?"

"You do do look familiar, but . . ." look familiar, but . . ."

"You came to visit me in Deutschland. One of my neighbors had contacted you; my vision had shown me watching a newscast on videotape about your death."

"Right," said Theo. "I remember." He couldn't recall the man's name, but he did remember the meeting, twenty years ago.

"And why was I watching that newscast? Why was the story about your death the one story on that newscast that I'd fast-forwarded ahead to see? Because I was checking to see if they had any evidence pointing to me. I'd never meant to kill anyone, but I will kill you if I have to. It's only fair, after all. You killed my wife."

Theo began to protest that he'd done no such thing, but then it came to him. Yes, he recalled his visit with this man. His wife had fallen down the stairs at a subway station during the time-displacement event; she'd broken her neck.

"There was no way we could have known what would happen-no way we could have prevented it."

"Of course you could have prevented it," snapped the man-Rusch, that was his name. It came back to Theo: Wolfgang Rusch. "Of course you could have. You had no business doing what you were doing. Trying to reproduce conditions at the birth of the universe! Trying to force the handiwork of G.o.d out into the light of day. Curiosity, they say, killed the cat. But it was you could have prevented it," snapped the man-Rusch, that was his name. It came back to Theo: Wolfgang Rusch. "Of course you could have. You had no business doing what you were doing. Trying to reproduce conditions at the birth of the universe! Trying to force the handiwork of G.o.d out into the light of day. Curiosity, they say, killed the cat. But it was your your curiosity-and it's my wife who's dead." curiosity-and it's my wife who's dead."

Theo didn't know what to say. How do you explain science-the need, the quest-to someone who is obviously a fanatic? "Look," said Theo, "where would the world be if we didn't-"

"You think I'm crazy?" said Rusch. "You think I'm nuts?" He shook his head. "I'm not nuts." He reached into his back pocket and pulled out his wallet. He fumbled with one hand to remove a yellow-and-blue laminated card from it and showed it to Theo.

Theo looked at it. It was a faculty ID card for The Humboldt University. "Tenured professor," said Rusch. "Department of Chemistry. Ph.D. from the Sorbonne." That's right-back in 2009, the man had said he taught chemistry. "If I had known your role in all this back then, I wouldn't have spoken to you. But you came to see me before CERN had gone public with its involvement."

"And now you want to kill me?" said Theo. His heart was pounding so hard he thought it was going to burst, and he could feel sweat breaking out all over his body. "That won't bring your wife back to life."

"Oh, yes it will," said Rusch.

He was was mad. Dammit, why had Theo come down into the tunnel alone? mad. Dammit, why had Theo come down into the tunnel alone?

"Not your death, of course," said Rusch. "But what I'm doing. Yes, it will bring Helena back. It's all because of the Pauli exclusion principle."

Theo didn't know what to say; the man was raving. "What?"

"Wolfgang Pauli," said Rusch, nodding. "I like to tell my students I was named for him, but I wasn't-I was named for my father's uncle." A pause. "Pauli's exclusion principle originally just applied to electrons: no two electrons could simultaneously occupy the same energy state. Later, it was expanded to include other subatomic particles."

Theo knew all this. He tried to hide his mounting panic. "So?"

"So I believe that the exclusion principle also applies to the concept of now. now. All the evidence is there: there can only be one All the evidence is there: there can only be one now now-throughout all of human history, we have all agreed on what moment is the present. Never has there been a moment that some part of humanity thought was now, while another part thought it was the past, and still another considered it to be in the future."

Theo lifted his shoulders slightly, not following where this was going.

"Don't you get it?" asked Rusch. "Don't you see? When you shifted the consciousness of humanity ahead twenty-one years-when you moved 'now' from 2009 to 2030-the 'nowness' that should have been experienced by the people in 2030 had to shift somewhere else. The exclusion principle! Every moment exists as 'now' for those frozen in it-you can't superimpose the 'now' of 2009 on top of that of 2030; the two nows cannot exist simultaneously. When you shifted the 2009 now forward, the 2030 now had to vacate that time. When I heard that you were going to be replicating the experiment again at the exact time the original visions had portrayed, it all fell into place." He paused. "The Sanduleak supernova will oscillate for many decades or centuries to come-surely tomorrow's attempt won't be the last. Do you think humanity's taste for seeing the future will be sated with one more peek? Of course not. We are ravenous in our desire. Since ancient times, no dream has been more seductive than that of knowing the future. 'nowness' that should have been experienced by the people in 2030 had to shift somewhere else. The exclusion principle! Every moment exists as 'now' for those frozen in it-you can't superimpose the 'now' of 2009 on top of that of 2030; the two nows cannot exist simultaneously. When you shifted the 2009 now forward, the 2030 now had to vacate that time. When I heard that you were going to be replicating the experiment again at the exact time the original visions had portrayed, it all fell into place." He paused. "The Sanduleak supernova will oscillate for many decades or centuries to come-surely tomorrow's attempt won't be the last. Do you think humanity's taste for seeing the future will be sated with one more peek? Of course not. We are ravenous in our desire. Since ancient times, no dream has been more seductive than that of knowing the future. Every Every time it is possible to shift the sense of now, we will do it-a.s.suming your experiment succeeds tomorrow." time it is possible to shift the sense of now, we will do it-a.s.suming your experiment succeeds tomorrow."

Theo glanced at the bomb. If he was reading the display properly, it had over fifty-five hours before it would explode. He was trying to think clearly; he'd had no idea just how unnerving it could be to have a gun aimed at your heart. "So-so-what are you saying? That if there's no opening here in 2030 for the consciousness of 2009 to jump into, then that first jump will never happen?"

"Exactly!"

"But that's crazy. The first jump has already already happened. We all lived through it twenty-one years ago. happened. We all lived through it twenty-one years ago.

"We didn't all all live through it," said Rusch sharply. live through it," said Rusch sharply.

"Well, no, but-"

"Yes, it happened. But I'm going to undo that. I'm going to retroactively rewrite the last two decades."

Theo didn't want to argue with the man, but: "That's not possible."

"Yes, it is. I know it is. Don't you see? I've already succeeded."

"What?"

"What did everybody's visions have in common the first time?" asked Rusch.

"I don't-"

"Leisure-time activities! The vast majority of the population seemed to be having a holiday, a day-off. And why? Because they'd all been told to stay home from work that day, to stay safe and secure, because CERN was going to attempt to replicate the time displacement. But something happened-something caused that replication to be called off, too late for people to go back to work. And so humanity got an unexpected holiday."

"It's more likely that what we saw the first time was simply a version of reality in which the precognition event had never occurred."

"Nonsense," said Rusch. "Sure, we saw some people at work-shopkeepers, street vendors, police, and so on. But most businesses were closed, weren't they? You've heard the speculation-that some great holiday would exist on Wednesday, October 23, in 2030, celebrated across the globe. A universal disarmament day, maybe, or a first-contact-with-aliens day. But now it is 2030, and you know as well as I do that no such holiday exists. Everyone was off work, preparing for a time displacement that didn't come. But they'd had some some advance warning that it wasn't going to come-meaning the news story that Large Hadron Collider had been damaged must have broken sometime earlier that day. Well, I've got my bomb set to go off two hours before the Sanduleak neutrinos will arrive." advance warning that it wasn't going to come-meaning the news story that Large Hadron Collider had been damaged must have broken sometime earlier that day. Well, I've got my bomb set to go off two hours before the Sanduleak neutrinos will arrive."

"But if something like that was in the news, surely someone would have seen it in their vision. Someone would have reported it."

"Who would be sitting home watching the news two hours into an unexpected holiday?" asked Rusch. "No, I'm sure the scenario I've described is correct. I will succeed in disabling CERN; the consciousness of 2030 Earth will stay put precisely where it belongs, and the change will propagate backwards from this point, back twenty-one years, rewriting history. My dear Helena, and all the other people who died because of your arrogance, will get to live again."

"You can't kill me," said Theo. "And you can't keep me here for two days. People will notice I'm missing, and they'll come down here to look for me, and they'll find your bomb and disarm it."

"A good point," said Rusch. Carefully keeping the Glock trained on Theo, he backed toward his bomb. He retrieved it from inside the air pump, lifting it up by its suitcase handle. He must have noted Theo's expression. "Don't worry," said Rusch. "It's not delicate." He placed the bomb on the tunnel floor and did something to the counter mechanism. Then he turned the case so that the long side was facing toward Theo. Theo looked down at the timer. It was still counting down, but now said 59 minutes, 56 seconds.

"The bomb will go off in one hour," said Rusch. "It's earlier than I planned, and with this much advanced notice, we're probably cheating people out of their holiday the day after tomorrow, but the gross effect will be the same. As long as the damage to the tunnel will take more than two days to repair, Der Zwischenfall Der Zwischenfall will not be replicated." He paused. "Now, let's you and I start walking. I'm not going to trust myself on a hovercart with you or-I imagine you took the monorail, no? Well, we won't. But in an hour, we can walk sufficiently far along the tunnel that neither of us will be hurt." He gestured with the gun. "So let's get going." will not be replicated." He paused. "Now, let's you and I start walking. I'm not going to trust myself on a hovercart with you or-I imagine you took the monorail, no? Well, we won't. But in an hour, we can walk sufficiently far along the tunnel that neither of us will be hurt." He gestured with the gun. "So let's get going."

They began to walk counterclockwise-toward the monorail-but before they'd gotten more than a dozen meters, Theo became conscious of a faint whine behind them. He turned around, and so did Rusch. Just rounding the curve of the tunnel off in the distance was another hovercart.

"d.a.m.n it," said Rusch. "Who's that?"

Jake Horowitz's red-and-gray hair was easy enough to make out, even at this distance, but the other person- G.o.d! It looked like- It was. Detective Helmut Drescher of Geneva's finest.

"I don't know," said Theo, pretending to squint.

The hovercart was rapidly approaching. Rusch looked left and right. There was so much equipment mounted on the sides of the tunnel wall that, with some advance warning, one could easily find crannies in which to hide. Rusch left the bomb at the side of the tunnel and started to retreat away from the approaching cart. But it was too late. Jake was clearly pointing at them. Rusch closed the distance between himself and Theo, and jabbed the pistol into Theo's ribs. Theo had never known his heart to beat so fast in his life.

Drescher had his own gun drawn as the hovercart settled to the tunnel floor about five meters away from Rusch and Theo.

"Who are you?" said Jake to Rusch.

"Careful!" blurted Theo. "He's got a gun."

Rusch looked panicked. A little bomb-planting was one thing, but hostage taking and potential murder was another. Still he jerked the Glock into Theo's side again. "That's right," said Rusch. "So back off."

Moot was now standing with legs spread for maximum stability, holding his own gun in both hands aimed directly at Rusch's heart. "I'm a police officer," said Moot. "Drop your weapon."

"Nein."

Moot's tone was absolutely even. "Drop your weapon or I will shoot."

Rusch's eyes darted left and right. "If you shoot, Dr. Procopides dies."

Theo's mind was racing. Had it gone down like this the first time? Rusch would have to shoot him not once, but three times, to match the vision. In a standoff like this, he might get one bullet into Theo's chest-not that it would take more-but surely as soon as he pulled the trigger the first time, Moot would blow Rusch away.

"Back off," said Rusch. "Back off!"

Jake looked as terrified as Theo felt, but Moot stood his ground. "Drop your weapon. You are under arrest."

Rusch's panic seemed to abate for a moment, as if he was simply stunned by the charge. If he really were just a university professor, he'd probably never been in trouble with the law his whole life. But then he brightened somewhat. "You can't arrest me."

"The h.e.l.l I can't," said Moot.

"What police force are you with?"

"Geneva's."

Rusch actually managed a small, panicked laugh. He jabbed Theo with the gun again. "Tell him where we are."

Theo's insides were churning. He didn't understand the question. "In the Large Hadron-"

Rusch jabbed again. "The country."

Theo felt his heart sinking. "Oh." d.a.m.n. G.o.d d.a.m.n it. "We're in France," he said. "The border goes right across the tunnel."

"So," said Rusch, looking at Moot, "you've got no jurisdiction here; Switzerland isn't an E.U. member. If you shoot me outside of your jurisdiction, that's murder."

Moot seemed to hesitate for a moment; the gun in his hand wavered. But then he brought it back to bear directly on Rusch's heart. "I will deal with whatever legalities there are after the fact," said Moot. "Drop your weapon now or I will shoot."

Rusch was standing so close to Theo that Theo could feel his breathing-rapid, shallow. The guy might hyperventilate.

"All right," said Rusch. "All right." He took a step away from Theo and- Kablam!

The report echoing in the tunnel.

Theo's heart stopping- -but only for a second.

Rusch's mouth had gone wide in horror, in terror, in fear- -at the realization of what he'd done- -as Moot Drescher staggered backward, tumbled and fell, landing on his back, dropping his gun, a growing pool of blood spreading across his shoulder.

"Oh my G.o.d!" shouted Jake, "Oh my G.o.d!" He surged forward, scrambling for Drescher's weapon.

Rusch looked absolutely dazed. Theo grabbed him from behind, putting his neck in a choke hold, and bringing his knee up into the small of Rusch's back. With his other hand, he tried to wrest the hot, smoking gun from Rusch.

Jake now had Drescher's gun. He tried to aim it at the combined form of Theo and Rusch, but his hands were shaking violently. Theo wrenched Rusch's arm and he dropped his gun. Theo dived out of the way, and Jake squeezed off a shot. But in his inexperienced, trembling hands, the bullet went wild, smashing into a fluorescent lighting tube overhead, which exploded in a shower of sparks and gla.s.s. Rusch was scrambling for his dropped gun, too. Neither he nor Theo seemed to be able to get a grip on it, and finally Theo kicked it from Rusch's grabbing hand. It skittered a dozen meters counterclockwise down the tunnel.

Theo had no weapon, and neither now did Rusch. Drescher was surrounded by a lake of blood, but seemed to be still alive; his chest was heaving. Jake tried another shot but it again missed its mark.

Rusch was only halfway to his feet before he started running after the Glock. Theo, realizing he'd never overtake him, decided to go the other way. "He's got a bomb," he shouted as he pa.s.sed Jake. "Help Moot!"

Jake nodded. Rusch had now recovered his own gun, and had turned around and was running, weapon held in front of him, toward Jake, Moot, and the retreating Theo.

Theo was running for all he was worth, footfalls echoing loudly in the tunnel. Up ahead was the aluminum suitcase containing the bomb. He stole a glance over his shoulder. Jake, still holding Moot's gun, had gone to his knees next to the cop. Rusch pa.s.sed them, keeping his own gun trained on Jake, preventing him from squeezing off another shot. Rusch turned around, running backward, keeping his weapon on Jake until he was out of Jake's shaky range. He then turned again and continued pursuing Theo.

Theo reached the bomb, scooping it up with one hand, and then- He got onto Rusch's hovercart, and slammed his foot against the activator pedal. Theo looked back as the cart started to speed away clockwise.

Rusch doubled back. Jake, apparently a.s.suming Rusch had gone, had set down Moot's gun and was pulling his own shirt off over his head, some b.u.t.tons, still done up-clearly, he wanted to use it as a pressure bandage to stanch the flow of blood out of Moot's body. Rusch had no trouble getting into the hovercart that had brought Jake and Moot to the scene, and he took off after Theo.

Theo had a good lead as he careened along the tunnel. But it was hardly straight-line flying-not only did the curve of the tunnel have to be negotiated, but so did all the giant pieces of equipment that jutted out w.i.l.l.y-nilly along its length.

Theo glanced at the bomb's display: 41 minutes, 18 seconds. He hoped Rusch had been telling the truth when he said the explosives weren't fragile. There were a series of unlabeled b.u.t.tons attached to the display-no way to tell which ones might reset the timer to a higher value, and which ones might cause the bomb to explode immediately. But if he could make it to the access station and get up to the surface, there would be plenty of time to abandon the bomb in the middle of one of the farmers' fields.

Theo's cart had a decided wobble-he was doubtless pushing it faster than its gyros could really deal with. He glanced behind himself again. At first, he began to breathe a sigh of relief-Rusch was nowhere to be seen-but after a second the pursuing cart appeared around the curving wall of the tunnel.

Darkness up ahead; Theo had only activated the roof lighting for a tiny arc of the tunnel's circ.u.mference. He hoped Jake had managed to stabilize Moot. d.a.m.n-he probably shouldn't have taken the hovercart; surely the need to get Moot to the surface was more important than protecting the equipment in the tunnel. He hoped Jake would realize that the monorail must be nearby.

s.h.i.t! Theo's cart touched the outer wall of the tunnel and started spinning around, its headlight beams cutting swaths through the darkness. He fought with the joystick that controlled the cart, trying to get it to keep from crashing into anything else. He got it going back in the right direction, but now Rusch's cart was about halfway down the visible part of the tunnel, instead of at its far end. Theo's cart touched the outer wall of the tunnel and started spinning around, its headlight beams cutting swaths through the darkness. He fought with the joystick that controlled the cart, trying to get it to keep from crashing into anything else. He got it going back in the right direction, but now Rusch's cart was about halfway down the visible part of the tunnel, instead of at its far end.

The hovercart wasn't going fast enough to make a real breeze, but it nonetheless felt like breakneck speed. Rusch still had the Glock, of course-but a hovercart wasn't like a car; you couldn't shoot out the tires in hopes of bringing it to a halt. The only sure way to stop such a vehicle was to shoot the driver; Theo had to keep pressure on the accelerator pedal for it to continue to move.

Theo kept rocking his cart left and right and raising and lowering it as much as he could in the cramped tunnel; if Rusch was trying to get a bead on him from the rear, he wanted to make himself a difficult target.

He checked the markers on the gently curving wall; the tunnel was divided into eight octants of about three and a half kilometers each, and each octant was subdivided into thirty-odd sections of a hundred meters apiece. According to the signage, he was in octant three, section twenty-two. The access station was at octant four, section thirty-three. He might just make it- An impact!

A shower of sparks.

The sounds of metal ripping.

Dammit, he wasn't paying enough attention; the hovercart had banged against one of the cryogenics units. It had almost flipped over, which would have dropped Theo and the bomb down onto the floor. Theo fought again with the controls, desperately trying to stabilize the cart. A furtive glance back confirmed his fears: the collision had slowed him down enough that Rusch was now only about fifty meters back. He'd have to be a h.e.l.l of a good shot to take Theo out at this distance in the dark, but if he got much closer . . .

The tunnel was constricted up ahead by more equipment; Theo had to drop the cart to only a few centimeters off the floor, but his control of the vehicle at its current speed was poor-the cart skittered across the flooring like a stone being skipped across a lake.

Another glance at the bomb's timing mechanism, the digits glowing bright blue in the dim light. Thirty-seven minutes.

Blam!

The bullet zipped past Theo; he instinctively ducked. It hit some metal fittings up ahead, illuminating the tunnel with sparks.