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Chapter One

Hans Walther Kleinman, one of the great theoretical physicists of our time, was drowning in his bathtub. A stranger with long, sinewy arms had pinned Hans's shoulders to the porcelain bottom.

Although the water was only thirty centimeters deep, the pinioning arms kept Hans from raising his face to the surface. He clawed at the stranger's hands, trying to loosen their grip, but the man was a shtarker, a young vicious brute, and Hans was a seventy-nine-year-old with arthritis and a weak heart. Flailing about, he kicked the sides of the tub, and the lukewarm water sloshed all around him. He couldn't get a good look at his attacker -- the man's face was a shifting, watery blur. Theshtarkermust have slipped into the apartment through the open window by the fi re escape, then rushed into the bathroom when he realized that Hans was inside.

As Hans struggled, he felt the pressure building in his chest. It started in the center, right under his sternum, and quickly filled his whole rib cage. A negative pressure, pushing inward from all sides, constricting his lungs. Within seconds it rose to his neck, a hot choking tightness, and Hans opened his mouth, gagging. Lukewarm water rushed down his throat, and now Hans devolved into a creature of pure panic, a twisting, squirming primitive animal going into its fi nal convulsions.No, no, no, no, no, no! Then he lay still, and as his vision faded he saw only the wavelets at the surface, rippling just a few centimeters above him. A Fourier series, he thought. And so beautiful.

But it wasn't the end, not yet. When Hans regained consciousness he was lying facedown on the cold tiled fl oor, coughing up bathwater. His eyes ached and his stomach lurched and each breath was an excruciating gasp. Coming back to life was actually more painful than dying. Then he felt a sharp blow to his back, right between his shoulder blades, and heard someone say in a jaunty voice, "Time to wake up!"

The stranger grabbed him by the elbows and rolled him over. The back of Hans's head banged against the wet tiles. Still breathing hard, he looked up at his attacker, who was kneeling on the bathroom rug. A huge man, a hundred kilograms at the least. Shoulder muscles bulging under his black T-shirt, camoufl age pants tucked into black leather boots. A bald head, disproportionately small compared with his body, with black stubble on his cheeks and a gray scar on his jaw. Most likely a junkie, Hans guessed. After he kills me, he'll tear the place apart, hunting for my valuables. Only then will the stupidputzrealize I don't have a goddamn cent.

Theshtarkerstretched his thin lips into a smile. "Now we'll have a little talk, yes? You can call me Simon, if you like."

The man's voice had an unusual accent that Hans couldn't place. His eyes were small and brown, his nose was crooked, and his skin was the color of a weathered brick. His features were ugly but indistinct -- he could be Spanish, Russian, Turkish, almost anything. Hans tried to say, "What do you want?" but when he opened his mouth he only retched again.

Simon looked amused. "Yes, yes, I'm so sorry about that. But I needed to show you that I'm serious. And better to do that right away, eh?"

Oddly enough, Hans wasn't afraid now. He'd already accepted the fact that this stranger was going to kill him. What disturbed him was the sheer impudence of the man, who kept smiling as Hans lay naked on the fl oor. It seemed clear what would happen next: Simon was going to order him to reveal the number of his ATM card. The same thing had happened to one of Hans's neighbors, an eighty-two-year-old woman who'd been attacked in her apartment and beaten until she gave up the number. No, Hans wasn't afraid -- he was furious! He coughed the last drops of bathwater out of his throat and propped himself up on his elbows. "You made a mistake this time, you ganef. I have no money. I don't even have a bank card."

"I don't want your money, Dr. Kleinman. I'm interested in physics, not money. You're familiar with the subject, I assume?"

At first Hans simply grew more enraged. Was thisputzmaking fun of him? Who did he think he was? After a moment, though, a more disturbing question occurred to him: How did this man find out my name? And how does he know I'm a physicist?

Simon seemed to guess what Hans was thinking. "Don't be so surprised, Professor. I'm not as ignorant as I look. I may not have any advanced degrees, but I'm a fast learner."

Hans had surmised by now that this man was no junkie. "Who are you? What are you doing here?"

"Think of it as a research project. On a very challenging and esoteric topic." His smile broadened. "I admit, some of the equations weren't easy to understand. But I have some friends, you see, and they explained it very well."

"Friends? What do you mean, friends?"

"Well, perhaps that's the wrong word.Clientswould probably be better. I have some very knowledgeable and well-financed clients. And they hired me to get some information from you."

"What are you talking about? Are you some kind of spy?"

Simon chuckled. "No, no, nothing so grandiose. I'm an independent contractor. Let's just leave it at that."

Hans's mind was racing now. Theshtarkerwas a spy, or maybe a terrorist. His exact affi liation was unclear -- Iran? North Korea? Al-Qaeda? -- but that didn't matter. They were all after the same thing. What Hans didn't understand was why the bastards had targeted him of all people. Like most nuclear physicists of his generation, Hans had done some classifi ed work for the Defense Department in the fi fties and sixties, but his specialty had been radioactivity studies. He'd never worked on bomb design or fabrication, and he'd spent most of his professional life doing theoretical research that was strictly nonmilitary. "I have some bad news for your clients, whoever they are," Hans said. "They picked the wrong physicist."

Simon shook his head. "No, I don't think so."

"What kind of information do you think I can give you? Uranium enrichment? I know nothing about that! And nothing about warhead design either. My fi eld is particle physics, not nuclear engineering. All my research papers are available on the Internet, there's nothing secret about them!"

The stranger shrugged, unperturbed. "You've jumped to the wrong conclusion, I'm afraid. I don't care about warheads and I don't care about your papers. I'm interested in someone else's work, not yours."

"Why are you in my apartment, then? Did you get the wrong address?"

Simon's face hardened. He pushed Hans down on his back and placed one hand flat on his rib cage, leaning forward so he could put his whole weight on it. "This person happens to be someone you knew. Your professor at Princeton fi fty-fi ve years ago? The wandering Jew from Bavaria? The man who wroteZur Elektrodynamik bewegter Körper? Surely you haven't forgotten him?"

Hans struggled to breathe. Theshtarker's hand felt impossibly heavy.Mein Gott, he thought. This can't be happening.

Simon leaned over some more, bringing his face so close that Hans could see the black hairs inside his nostrils. "He admired you, Dr. Kleinman. He thought you were one of his most promising assistants. You worked together quite closely in his last few years, didn't you?"

Hans couldn't have replied even if he'd wanted to. Simon was pushing down on him so hard he could feel his vertebrae grinding against the cold tiles.

"Yes, he admired you. But more than that, he trusted you. He conferred with you about everything he worked on during those years. Including hisEinheitliche Feldtheorie."

At just that moment one of Hans's ribs snapped. On his left side, on the outer curve, where the tensile strain was greatest. The pain knifed through his chest and Hans opened his mouth to scream, but he couldn't even draw enough breath to cry out.Oh Gott, Gott im Himmel! All at once his rational mind disintegrated, and he was afraid, he was terrified! Because he saw what this stranger wanted from him, and he knew that in the end he would be unable to resist.

Simon finally eased off and removed his hand from Hans's chest. Hans took a deep breath, and as the air whooshed in he felt the knife of pain again on his left side. His pleural membrane was torn, which meant that his left lung would soon collapse. He was weeping from the pain and shuddering with each breath. Simon stood over him with his hands on his hips, smiling contentedly, quite satisfied with his work. "So do we understand each other? Do you see what I'm looking for?"

Hans nodded, then closed his eyes. I'm sorry,Herr Doktor, he thought. I'm going to betray you now. And in his mind's eye he saw the professor again, saw him as clearly as if the great man were standing right there in the bathroom. But it was nothing like the pictures that everyone knew, the photographs of the unkempt genius with the wild white hair. What Hans remembered was the professor in the last months of his life. The drawn cheeks, the sunken eyes, the defeated grimace. The man who'd glimpsed the truth but, for the sake of the world, couldn't speak it out loud.

Hans felt a kick in his side, just below his broken rib. The pain ripped through his torso, and his eyes sprang open. One of Simon's leather boots rested on Hans's bare hip. "No time for sleeping," he said. "We have work to do. I'm going to get some paper from your desk and you're going to write everything down." He turned around and walked out of the bathroom. "If there's something I don't understand, you'll explain it to me. Like a seminar, yes? Who knows, you might even enjoy it."

Simon headed down the hallway toward Hans's bedroom. A moment later Hans heard rummaging noises. With the stranger out of sight, some of Hans's fear lifted and he was able to think again, at least until the bastard came back. And what he thought about were theshtarker's boots, his shiny black storm-trooper boots. Hans felt a wave of disgust. The man was trying to look like a Nazi. In essence, that's what he was, a Nazi, no different from the thugs in brown uniforms that Hans had seen marching down the streets of Frankfurt when he was seven years old. And the people Simon worked for, those nameless "clients"? Who were they if not Nazis?

Simon returned holding a ballpoint pen in one hand and a legal pad in the other. "All right, from the beginning," he said. "I want you to write the revised field equation."

He bent over, offering the pen and pad, but Hans didn't take them. His lung was collapsing and each breath was a torture, but he wasn't going to help this Nazi. "Go to hell," he rasped.

Simon gave him a mildly scolding look, the kind you'd give to a misbehaving five-year-old. "You know what I think, Dr. Kleinman? I think you need another bath."

In one swift motion he picked Hans up and plunged him into the water again. Once more Hans struggled to raise his face to the surface, bashing himself against the sides of the tub as he clawed at theshtarker's arms. If anything, the second time was more terrifying than the fi rst, because now Hans knew exactly what lay ahead -- the tightening agony, the frantic twisting, the mindless descent into blackness.

Hans fell deeper into unconsciousness this time. It took a tremendous effort to emerge from the abyss, and even after Hans opened his eyes he felt like he hadn't fully awoken. His vision was fuzzy around the edges and he could take only shallow breaths.

"Are you there, Dr. Kleinman? Can you hear me?"

The voice sounded muffled now. When Hans looked up he saw the silhouette of theshtarker, but his body seemed to be surrounded by a penumbra of vibrating particles.

"I really wish you'd be more reasonable, Dr. Kleinman. If you look at the situation in a logical way, you'll realize that all this subterfuge is absurd. You can't hide something like this forever."

Hans looked a little closer at the penumbra surrounding the man and saw that the particles weren't actually vibrating -- they were popping in and out of existence, pairs of particles and antiparticles appearing like magic from the quantum vacuum and then disappearing just as quickly. This is amazing, Hans thought. If only I had a camera!

"Even if you don't help us, my clients will get what they want. Perhaps you didn't know this, but your professor had other confidants. He thought it would be clever to parcel the information among them. We've already contacted a few of these old gentlemen, and they've been most helpful. One way or another, we'll get what we need. So why make this hard on yourself?"

The evanescent particles seemed to grow larger as Hans stared at them. Upon closer inspection it became clear that they weren't particles at all but infi nitely thin strings stretching from one curtain of space to another. The strings shivered between the undulating curtains, which curled into tubes and cones and manifolds. And the whole elaborate dance was proceeding exactly as predicted, exactly asHerr Doktorhad described!

"I'm sorry, Dr. Kleinman, but my patience is wearing thin. I don't enjoy doing this, but you leave me no choice."

The man kicked him three times in the left side of his chest, but Hans didn't even feel it. The diaphanous curtains of space had folded around him. Hans could see them so clearly, like curving sheets of blown glass, brilliant and impenetrable, yet soft to the touch. But the other man obviously couldn't see them. Who was this man, anyway? He looked so clownish standing there in his black leather boots. "Don't you see them?" Hans whispered. "They're right in front of your eyes!"

The man let out a sigh. "I guess this will require a more vigorous kind of persuasion." He retreated to the hallway and opened the door to the linen closet. "Let's see what we have here." After a moment he returned to the bathroom carrying a plastic bottle of rubbing alcohol and a steam iron. "Dr. Kleinman, could you tell me where the nearest electric outlet is?"

Hans forgot about the man. He saw nothing but the lacy folds of the universe, curving around him like an infinitely soft blanket.

Copyright © 2008 by Mark Alpert

Chapter Two

David Swift was in an unusually good mood. he and Jonah, his seven-year-old son, had just spent a marvelous afternoon in Central Park. To cap off the day, David had bought ice-cream cones from a pushcart at Seventy-second Street, and now father and son were strolling through the sultry June twilight toward David's ex-wife's apartment. Jonah was in a good mood, too, because in his right hand -- his left hand held the ice cream cone -- he brandished a brand-new, triple-shot Super Soaker. As Jonah walked down the sidewalk he idly pointed the high-tech water gun at various random targets -- windows, mailboxes, a few clusters of pigeons -- but David wasn't concerned. He'd emptied the gun's reservoir before they'd left the park.

Jonah somehow managed to lick his ice cream while sighting down the barrel of the Super Soaker. "So how does it work again? Why does the water come out so fast?"

David had explained the process twice before, but he didn't mind repeating it. He loved having this kind of conversation with his son. "When you move that red thing, the pump handle? That pushes the water from the big reservoir to the smaller one."

"Wait, where's the smaller one?"

David pointed at the back of the gun. "It's right here. The smaller reservoir has some air in it, and when you pump water into the tank there's less room for the air. The air molecules get squeezed together and start pushing on the water."

"I don't get it. Why do they push the water?"

"Because air molecules are always bouncing around, see? And when you squeeze them together, they bounce against the water more."

"Can I bring the gun to school for show-and-tell?"

"Uh, I don't know..."

"Why not? It's science, right?"

"I don't think they allow water guns in school. But you're right, there's definitely science in this thing. The guy who invented the Super Soaker was a scientist. A nuclear engineer who worked for NASA."

A bus lunged down Columbus Avenue and Jonah tracked it with his water gun. He seemed to be losing interest in the physics of Super Soakers. "Why didn'tyoubecome a scientist, Dad?"

David thought for a second before answering. "Well, not everyone can be a scientist. But I write books about the history of science and that's also fun. I get to learn about famous people like Isaac Newton and Albert Einstein and teach courses about them."

"I don't want to do that. I'm gonna be a real scientist. I'm gonna invent a spaceship that can fly to Pluto in five seconds."

It would've been amusing to talk about the Pluto spaceship, but now David was uncomfortable. He felt a strong need to improve his standing in his son's eyes. "A long time ago, when I was in graduate school, I did some real science. And it was all about space."

Jonah turned away from the street and stared at him. "You mean spaceships?" he asked hopefully. "Spaceships that can go a billion miles per second?"

"No, it was about the shape of space. What space would look like if there were only two dimensions instead of three."

"I don't get it. What's a dimension?"

"A universe with two dimensions has length and width, but no depth. Like a giant sheet." David held out his hands, palms down, as if he were smoothing an infinite sheet. "I had this teacher, Professor Kleinman? He's one of the smartest scientists in the whole world. And we wrote a paper together about two-dimensional universes."

"A paper?" The excitement seemed to drain from Jonah's face.

"Yeah, that's what scientists do, they write papers about their discoveries. So their colleagues can see what they've done."

Jonah turned back to watch the traffic. He was so bored, he didn't even bother to ask what the wordcolleaguesmeant. "I'm gonna ask Mom if I can take the Super Soaker to show-and-tell."

A minute later they walked into the apartment building where Jonah and his mother lived. David had lived there, too, until two years ago, when he and Karen had separated. Now he had a small apartment of his own farther uptown, closer to his job at Columbia University. Every weekday he picked up Jonah from school at three o'clock and delivered him to his mother four hours later. The arrangement allowed them to avoid the considerable expense of hiring a nanny. But David's heart always sank as he walked through the lobby of his old building and entered the sluggish elevator. He felt like an exile.

When they finally reached the fourteenth floor, David saw Karen standing in the apartment's doorway. She hadn't changed out of her work clothes yet; she wore black pumps and a gray business suit, the standard uniform of a corporate lawyer. With her arms folded across her chest, she scrutinized her ex-husband, glancing with evident disapproval at the stubble on David's face and his mud-caked jeans and the T-shirt emblazoned with the name of his softball team, the Hitless Historians. Then her eyes fixed on the Super Soaker. Sensing trouble, Jonah handed the gun to David and slipped past his mother into the apartment. "Gotta pee," he yelled as he ran to the bathroom.

Karen shook her head as she stared at the water gun. A stray lock of blond hair dangled beside her left cheek. She was still beautiful, David thought, but it was a cold beauty, cold and unyielding. She raised her hand to her face and whisked the blond lock to the side. "What the hell were you thinking?"

David had prepared himself for this. "Look, I already told Jonah the rules. No shooting at people. We went to the park and shot at the rocks and trees. It was fun."

"You think a machine gun is an appropriate toy for a seven-year-old?"

"It's not a machine gun, all right? And the box said, 'Ages seven and up.'"

Karen narrowed her eyes and pursed her lips. It was an expression she often made in the heat of an argument, and David had always hated it. "You know what kids do with those Super Soakers?" she said. "There was a story about it on the news last night. A bunch of kids in Staten Island put gasoline in the gun instead of water so they could turn it into a flamethrower. They nearly burned down their whole neighborhood."

David took a deep breath. He didn't want to fight with Karen anymore. That was why they'd split up -- they were fighting all the time in front of Jonah. So it made no sense at all to continue this conversation. "Okay, okay, calm down. Just tell me what you want me to do."

"Take the gun home with you. You can let Jonah play with it when you're watching him, but I don't want that thing in my house."

Before David could respond, he heard the telephone ring inside the apartment. Then he heard Jonah call out, "I'll get it!" Karen's eyes swept sideways and for a moment it looked like she was going to make a dash for the phone, but instead she just cocked her ear to listen. David wondered if it was her new boyfriend. She'd started dating another lawyer, a hearty gray-haired gent with two former wives and a lot of money. David wasn't jealous in the usual sense -- he'd lost his passion for Karen a long time ago. What he couldn't stand was the thought of that glad-handing coot getting chummy with Jonah.

Jonah came to the doorway with the cordless phone in his hand. He stopped in his tracks, probably puzzled by the anxious looks on both his parents' faces. Then he held the phone toward David. "It's for you, Dad."

Karen's face fell. She looked betrayed. "That's strange. Why would anyone call you here? Don't they have your new number?"

Jonah shrugged. "The man on the phone said he's with the police."

David sat in the backseat of a taxi speeding north toward St. Luke's Hospital. It was getting dark now and all the eager Thursday-night couples were lining up outside the restaurants and bars on Amsterdam Avenue. As the taxi hurtled through the traffi c, careening past the slow-moving buses and delivery trucks, David stared at the neon signs above the restaurants, the lurid orange letters fl ashing by.

Attacked, the police detective said. Professor Kleinman had been attacked in his apartment on 127th Street. Now he was in critical condition at the emergency room of St. Luke's. And he'd asked for David Swift. Whispered a phone number to the paramedics. You better hurry, the detective said. David asked, "Why? What's wrong?" and the detective said, "Just hurry."

David squirmed with guilt. He hadn't seen Professor Kleinman in over three years. The old man had become a recluse since he'd retired from Columbia's physics department. Lived in a tiny apartment on the edge of West Harlem, gave all his money to Israel. No wife, no kids. His whole life had been physics.

Twenty years earlier, when David was a grad student, Kleinman had been his adviser. David had liked him from the start. Neither aloof nor severe, he sprinkled Yiddish into his discourses on quantum theory. Once a week David went to Kleinman's office to hear him elucidate the mysteries of wave functions and virtual particles. Unfortunately, all the patient explanations weren't enough; after two years of frustration, David had to admit he was in over his head. He simply wasn't smart enough to be a physicist. So he quit the graduate program and switched to the next best thing: a Ph.D. in the history of science.

Kleinman was disappointed but understanding. Despite David's failings as a physics student, the old man had grown fond of him. They stayed in touch over the next ten years, and when David began research for his book -- a study of Albert Einstein's collaborations with his various assistants -- Kleinman offered his personal recollections of the man he calledHerr Doktor. The book,On the Shoulders of Giants, was tremendously successful and made David's reputation. He was now a full professor in Columbia's History of Science program. But David knew it didn't mean much. Compared with a genius like Kleinman, he'd accomplished nothing.

The taxi screeched to a halt in front of the St. Luke's emergency room. After paying the driver, David rushed through the automatic glass doors and immediately spied a trio of New York City police offi cers standing next to the intake desk. Two of them were in uniform: a middle-aged sergeant with a bulging gut and a tall, thin rookie who looked like he was barely out of high school. The third was a plainclothes detective, a handsome Latino man in a neatly pressed suit. That's the man who called me, David thought. He remembered the detective's name: Rodriguez.

His heart pounding, David approached the offi cers. "Excuse me? I'm David Swift. Are you Detective Rodriguez?"

The detective nodded soberly. The two patrolmen, though, seemed amused. The paunchy sergeant smiled at David. "Hey, you got a permit for that thing?"

He pointed at the Super Soaker. David was so distracted he'd forgotten he was still holding Jonah's water gun.

Rodriguez frowned at the sergeant. He was all business. "Thank you for coming, Mr. Swift. Are you a relative of Mr. Kleinman?"

"No, no, I'm just a friend. A former student, actually."

The detective looked puzzled. "He was your teacher?"

"Yes, at Columbia. How is he? Is he badly hurt?"

Rodriguez placed a hand on David's shoulder. "Please, come with us. He's conscious but not answering our questions. He insists on talking to you."

The detective led David down a corridor while the two patrolmen walked behind. They passed a pair of nurses who looked at them gravely. This was not a good sign. "What happened?" David asked. "You said he was attacked?"

"We got a report of a burglary in progress," Rodriguez said

without emotion. "Someone across the street saw a man enter the apartment from the fi re escape. When the offi cers arrived they found Mr. Kleinman in the bathroom, critically injured. That's all we know at this time."

"What do you mean, critically injured?"

The detective looked straight ahead. "Whoever did this was a very sick individual. Mr. Kleinman has third-degree burns on his face, chest, and genitals. He also has a collapsed lung and damage to his other organs. The doctors say his heart is failing now. I'm very sorry, Mr. Swift."

David's throat tightened. "Can't they operate?"

Rodriguez shook his head. "He wouldn't survive."

"Goddamn it," David muttered. He felt more anger than grief. He clenched his fists as he thought of Dr. Hans Walther Kleinman, that kind and brilliant old man, being pummeled by some sadistic street punk.

They came to a room marked TRAUMA CENTER. Through the doorway David saw two more nurses in green scrubs standing beside a bed that was surrounded by medical equipment -- a cardiac monitor, a crash cart, a defi brillator, an IV pole. From the corridor David couldn't see who was lying on the bed. He was about to step into the room when Detective Rodriguez grabbed his arm.

"I know this will be difficult, Mr. Swift, but we need your help. I want you to ask Mr. Kleinman if he remembers anything from the attack. The paramedics said that while he was in the ambulance, he kept repeating a couple of names." Rodriguez looked over his shoulder at the rookie patrolman. "What were those names again?"

The boy cop flipped through the pages of his notebook. "Uh, hold on a second. They were German names, I remember that. Okay, here they are. Einhard Liggin and Feld Terry."

Rodriguez looked intently at David. "Do you know either of those people? Were they associates of Mr. Kleinman?"

David repeated the names silently: Einhard Liggin, Feld Terry. They were unusual, even for German. And then it hit him.

"They're not names," he said. "It's two words in German.Einheitliche Feldtheorie."

"What does it mean?"

"Unified field theory."

Rodriguez just stared at him. "And what the hell is that?"

David decided to give the same explanation he would've given Jonah. "It's a theory that would explain all the forces of nature. Everything from gravity to electricity to the nuclear forces. It's the Holy Grail of physics. Researchers have been working on the problem for decades, but no one's come up with the theory yet."

The paunchy sergeant chuckled. "Well, there's our perp. The unified field theory. Should I put out an all-points?"

Rodriguez frowned at the sergeant again, then turned back to David. "Just ask Mr. Kleinman what he remembers. Anything at all would be helpful."

David said, "All right, I'll try," but he was perplexed now. Why would Kleinman repeat those particular words? Unified field theory was a somewhat old-fashioned term. Most physicists now referred to it as string theory or M-theory or quantum gravity, which were the names of the more recent approaches to the problem. What's more, Kleinman hadn't been enthusiastic about any of these approaches. His fellow physicists were going about it all wrong, he'd said. Instead of trying to understand how the universe works, they were building gaudy towers of mathematical formulas.

Rodriguez gave him an impatient look. He took the Super Soaker out of David's hands and nudged him toward the Trauma Center. "You better go in now. He may not have long."

David nodded, then stepped into the room. As he approached the bed, the two nurses tactfully backed off and focused on the cardiac monitor.

What he noticed fi rst were the bandages, the thick gauze pad taped to the right side of Kleinman's face and the blood-soaked wrappings across his chest. The dressings covered most of Kleinman's body and yet they still didn't conceal all his injuries. David could see patches of dried blood under the old man's white hair and purple hand-shaped bruises on both of his shoulders. But the worst thing was the dark blue tinge to his skin. David was familiar enough with physiology to know what it meant: Kleinman's heart could no longer pump the oxygenated blood from his lungs to the rest of his body. The doctors had strapped an oxygen mask to his face and put him in a sitting position to drain the fluid from his lungs, but these interventions weren't having much effect. David felt a fullness in his own chest as he stared at Professor Kleinman. The old man already looked like a corpse.

After a few seconds, though, the corpse began to move. Kleinman opened his eyes and slowly raised his left hand to his face. With curled fingers he tapped the clear plastic mask that covered his mouth and nose. David leaned over the bed. "Dr. Kleinman? It's me, David. Can you hear me?"

Although the professor's eyes were watery and dull, they locked on David. Kleinman tapped his oxygen mask again and then grasped the vinyl air bag that hung below, filling and emptying like a third lung. After fumbling for a moment, he got a good grip on the thing and started tugging.

David grew alarmed. "Is something wrong? Is the air not getting through?"

Kleinman pulled harder at the bag, which twisted in his hand. His lips were moving behind the plastic mask. David leaned closer. "What is it? What's wrong?"

The old man shook his head. A drop of sweat ran down his brow. "Don't you see it?" he whispered from behind the mask. "Don't you see?"

"See what?"

Kleinman let go of the bag and held his hand up in the air, turning it around slowly as if he were displaying a prize. "So beautiful," he whispered.

David heard a moist rattle in Kleinman's chest. It was the fluid backing up into his lungs. "Do you know where you are, Professor? You're in the hospital."

Kleinman kept staring with wonder at his hand, or more specifi cally, at the empty space cupped in his palm. "Yes, yes," he rasped.

"Someone attacked you in your apartment. The police want to know if you remember anything."

The old man coughed, spraying pinkish spittle on the inside of his mask. But his eyes remained on the invisible prize in his hand. "He was right.Mein Gott, he was right!"

David bit his lip. He knew now beyond a doubt that Kleinman was dying, because he'd witnessed a similar struggle once before. Ten years earlier he'd stood by his father's hospital bed and watched him die of liver cancer. David's father, John Swift, was a bus driver and former boxer who'd abandoned his family and drunk himself to death. At the end he didn't even recognize his son. Instead he thrashed under the bedsheets and cursed the names of the oncefamous welterweights who'd beaten him senseless thirty years before.

David grasped Kleinman's hand. It was soft and limp and very cold. "Professor, please listen. This is important."

The old man's eyes locked on him again. They were the only part of him that still seemed alive. "Everyone thought...that he failed. But he succeeded. He succeeded!" Kleinman spoke in short bursts, taking shallow breaths in between. "But he couldn't...publish it.Herr Doktorsaw...the danger. Much worse...than a bomb. Destroyer...of worlds."

David stared at the old man.Herr Doktor? Destroyer of worlds? He clasped Kleinman's hand a bit tighter. "Try to stay with me, okay? You need to tell me about the man who hurt you. Do you remember what he looked like?"

The professor's face was shiny with sweat now. "That's why...theshtarkercame. That's why...he tortured me."

"Tortured?" David felt a sickening jolt.

"Yes, yes. He wanted me...to write it down. But I didn't. I didn't!"

"Write what down? What did he want?"

Kleinman smiled behind the mask. "Einheitliche Feldtheorie," he whispered. "Herr Doktor's...last gift."

David was bewildered. The easiest explanation was that the professor was hallucinating. The trauma of the attack had dredged up memories from half a century ago, when Hans Kleinman was a young physicist at Princeton's Institute for Advanced Study, hired to assist the legendary but ailing Albert Einstein. David had written about it in his book: the endless stream of calculations on the blackboard in Einstein's office, the long futile search for a field equation that would encompass both gravity and electromagnetism. It was not unreasonable that Kleinman, in his fi nal delirium, would think back to those days. And yet the old man didn't seem delirious at that moment. His chest was wheezing and he was sweating profusely, but his face was calm.

"I'm sorry, David," he rasped. "Sorry I never...told you.Herr Doktorsaw...the danger. But he couldn't...he couldn't..." Kleinman coughed again, and his whole body shuddered. "He couldn't burn...his notebooks. The theory was...too beautiful." He let out another violent cough and then he suddenly doubled over.

One of the nurses rushed to the other side of Kleinman's bed. Grabbing the professor by his bruised shoulders, she propped him back up to a sitting position. David, who was still holding Kleinman's hand, saw that his oxygen mask was fi lled with pink froth.

The nurse quickly removed the mask and cleaned out the sputum. But when she tried to put it back on, Kleinman shook his head. She grasped the back of his neck to hold him still, but he batted the mask away with his free hand. "No!" he croaked. "Stop it! Enough!"

The nurse glared at him, then turned to her partner, who was still staring at the cardiac monitor. "Go get the resident," she ordered. "We need to intubate."

Kleinman leaned against David, who put his arm around the old man to keep him from toppling. The gurgling in his chest seemed louder now and his eyes darted wildly. "I'm dying," he rasped. "There's not...much time."

David's eyes began to sting. "It's all right, Professor. You're going to be all -- "

Kleinman raised his hand and gripped the collar of David's shirt. "Listen...David. You must...be careful. Your paper...remember? The one we worked on...together? Remember?"

It took David a moment to realize what the professor was referring to. "You mean back in grad school? 'General Relativity in a Two-Dimensional Spacetime'? That paper?"

He nodded. "Yes, yes...you were close...very close...to the truth. Once I'm gone...they might come after you."

David felt an uneasy prickle in his stomach. "Who are you talking about?"

Kleinman tightened his grip on David's collar. "I have...a key.Herr Doktorgave me...this gift. And now I give it...to you. Keep it...safe. Don't let...them get it. Understand? No one!"

"A key? What -- "

"No time...no time! Just listen!" With surprising strength, Kleinman pulled David close. The old man's wet lips brushed his ear. "Remember...the numbers. Four, zero...two, six...three, six...seven, nine...fi ve, six...four, four...seven, eight, zero, zero."

As soon as he spoke the last digit, the professor let go of David's collar and slumped against his chest. "Now repeat...the sequence."

Despite his confusion, David did as he was told. He put his lips near Kleinman's ear and repeated the sequence. Although David had never been able to master the equations of quantum physics, he had an aptitude for memorizing long strings of numbers. When he was done, the old man nodded.

"Good boy," he murmured against David's shirt. "Good boy."

The nurse stood beside the crash cart, preparing for the intubation. David watched her pick up a silver, scythe-shaped instrument and a long plastic tube with black tick marks along its length. They're going to slip that thing down the professor's throat, he thought. And then David felt something warm against his stomach. He looked down and saw a rivulet of viscous pink fl uid spilling out of Kleinman's mouth and pouring down his chin. The old man's eyes were closed and his chest had stopped gurgling.

When the emergency-room resident finally arrived, he kicked David out of the Trauma Center and called for reinforcements. Soon half a dozen doctors and nurses surrounded Kleinman's bed, trying to resuscitate the professor. But David knew it was hopeless. Hans Kleinman was gone.

Rodriguez and the two patrolmen intercepted him as he lurched down the corridor. The detective, still holding the Super Soaker, wore a sympathetic look. He handed the water gun back to David. "How did it go, Mr. Swift? Did he tell you anything?"

David shook his head. "I'm sorry. He was going in and out. It didn't make a lot of sense."

"Well, what did he say? Was it a robbery?"

"No. He said he was tortured."

"Tortured? Why?"

Before David could answer, someone down the hallway shouted, "Hey, you! Hold it right there!"

It was a tall, ruddy, thick-necked man wearing a crew cut and a gray suit. He was flanked by two more ex-linebackers who looked much the same. The three of them marched down the corridor at a brisk clip. When they reached the cops, the guy in the middle took his ID out of his jacket and flashed the badge. "Agent Hawley, FBI," he announced. "Are you the offi cers working the Kleinman case?"

The fat sergeant and the rookie patrolman stepped forward so that they stood shoulder to shoulder with Rodriguez. They sneered in unison at the federal agents. "Yeah, that's our case," Rodriguez replied.

Agent Hawley gave a hand signal to one of his companions, who headed for the Trauma Center. Then Hawley reached into the pocket of his jacket again and pulled out a folded letter. "We're taking over now," he said, passing the letter to Rodriguez. "Here's the authorization from the U.S. Attorney's Offi ce."

Rodriguez unfolded the letter. He scowled as he read it. "This is bullshit. You don't have jurisdiction here."

Hawley's face was expressionless. "If you have a complaint, you can take it up with the U.S. attorney."

David studied Agent Hawley, who was turning his blank face from left to right, surveying the hallway. Judging by his accent, he definitely wasn't from New York. He sounded like an Oklahoma farm boy who'd picked up his conversational skills in the Marine Corps. David wondered why this no-nonsense FBI man was so interested in the murder of a retired physicist. He felt the prickle in his stomach again.

As if sensing David's discomfort, Agent Hawley pointed at him. "Who's this guy?" he asked Rodriguez. "What's he doing here?"

The detective shrugged. "Kleinman asked for him. His name's David Swift. They just finished talking and he -- "

"Son of a bitch! You let this guy talk to Kleinman?"

David frowned. This agent was a real asshole. "I was trying to help," he said. "If you'd shut up for a minute, the detective would explain it to you."

Hawley abruptly turned away from Rodriguez. He narrowed his eyes and stepped toward David. "Are you a physicist, Mr. Swift?"

The agent loomed over him, but David kept his voice steady. "No, I'm a historian. And it's Dr. Swift, if you don't mind."

While Hawley tried to stare him down, the agent who'd gone to the Trauma Center returned. He sidled up to Hawley and whispered something in his ear. For a fraction of a second Hawley tightened his lips into a grimace. Then his face turned blank and hard again. "Kleinman's dead, Mr. Swift. That means you're coming with us."

David almost laughed. "Coming with you? I don't think so."

But before the last words were out of his mouth, the third FBI agent had slipped behind him, yanked back his arms, and snapped a pair of handcuffs around his wrists. The Super Soaker clattered to the floor.

"What the hell are you doing?" David yelled. "Am I under arrest?"

Hawley didn't bother to reply. He grabbed David's arm just above the elbow and turned him around. The agent who'd handcuffed him picked up the Super Soaker, holding it at arm's length as if it were a real weapon. Then all three FBI men escorted David down the corridor, moving swiftly past the dumbfounded doctors and nurses. David looked over his shoulder at Detective Rodriguez and the patrolmen, but the offi cers just stood there.

One of the agents marched ahead and opened the door to a stairway. David was too scared to protest. As they hurried down the stairs toward the emergency exit, he remembered something Professor Kleinman had said just a few minutes before. It was part of a famous quote from J. Robert Oppenheimer, another great physicist who'd worked with Einstein. The words had run through Oppenheimer's mind when he witnessed the fi rst test of the atomic bomb.

Now I am become Death, the destroyer of worlds.

Copyright © 2008 by Mark Alpert

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Excerpted from Final Theory by Mark Alpert
All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.