Landis, Geoffrey A - SS - Ripples in the Dirac Sea.pdf - Geoffrey A Landis - przemosta

RIPPLES IN THE DIRAC SEA

Geoffrey A. Landis

Geoff Landis has just completed a postdoctoral fellowship at NASA's Lewis Research Center in

Cleveland. He writes science fiction grounded in the hard sciences, but his first story, "Elemental," a Hugo

nominee for best novella of 1984, dealt with magical matters in a scientific context and appeared in

Analog . Later work has been published in Isaac Asimov's Science Fiction Magazine, Pulphouse , and

Amazing Stories .

About his award-winning short story, Geoff writes, " 'Ripples in the Dirac Sea' was an experimental story

for me. Quite a number of disparate threads wove into the final narrative. One important thread was my

feeling that a story involving time travel should have a nonlinear narrative to reflect the discontinuous way

the characters experience time.

"I also wanted to see if it was possible to write a story in which real physics is presented. Very little of

modern SF goes beyond the early quantum mechanics of Heisenberg and Schrodinger, work which is

admittedly remarkable and beautiful, but by no means the end of the story. Here I tried to invoke some of

the strangeness and beauty— I might even say sense of wonder—of the physics of Paul Adrien Maurice

Dirac. In 'Ripples' I decided to explore the inconsistency between Dirac's relativistic quantum mechanics

and the mathematics of infinity developed by Cantor and others (as far as I can tell, a quite real

inconsistency). The Dirac sea is also real, not an invention of mine— despite the very science-fictional

feel of an infinitely dense sea of negative energy that surrounds and permeates us.

"Among the other threads, one might distinguish my attempts to deal with a protagonist who has both

great power and utter helplessness at the same time, my father's death of complications from a cerebral

aneurysm in 1984, along with some of my thoughts about the philosophical implications of time travel, the

sixties, dinosaurs, and various other things."

My death looms over me like a tidal wave, rushing toward me with an inexorable slow-motion majesty.

And yet I flee, pointless though it may be.

I depart, and my ripples diverge to infinity, like waves smoothing out the footprints of forgotten

travellers.

WE WERE SO CAREFUL to avoid any paradox, the day we first tested my machine. We pasted a

duct-tape cross onto the concrete floor of a windowless lab, placed an alarm clock on the mark, and

locked the door. An hour later we came back, removed the clock, and put the experimental machine in

the room with a super-eight camera set in the coils. I aimed the camera at the X, and one of my grad

students programmed the machine to send the camera back half an hour, stay in the past five minutes,

then return. It left and returned without even a flicker. When we developed the film, the time on the clock

was half an hour before we loaded the camera. We'd succeeded in opening the door into the past. We

celebrated with coffee and champagne.

Now that I know a lot more about time, I understand our mistake, that we had not thought to put a

movie camera in the room with the clock to photograph the machine as it arrived from the future. But

what is obvious to me now was not obvious then.

I ARRIVE, and the ripples converge to the instant now from the vastness of the infinite sea.

To San Francisco, June 8, 1965. A warm breeze riffles across dandelion-speckled grass, while puffy

white clouds form strange and wondrous shapes for our entertainment. Yet so very few people pause to

enjoy it. They scurry about, diligently preoccupied, believing that if they act busy enough, they must be

important. "They hurry so," I say. "Why can't they slow down, sit back, enjoy the day?"

"They're trapped in the illusion of time," says Dancer. He lies on his back and blows a soap bubble, his

hair flopping back long and brown in a time when "long" hair meant anything below the ear. A puff of

breeze takes the bubble down the hill and into the stream of pedestrians. They uniformly ignore it.

"They're caught in the belief that what they do is important to some future goal." The bubble pops against

a briefcase, and Dancer blows another. "You and I, we know how false an illusion that is. There is no

past, no future, only the now, eternal."

He was right, more right than he could have possibly imagined.

Once I, too, was preoccupied and self-important. Once I was brilliant and ambitious. I was twenty-eight

years old, and I made the greatest discovery in the world.

FROM MY hiding place I watched him come up the service elevator. He was thin almost to the point of

starvation, a nervous man with stringy blond hair and an armless white T-shirt. He looked up and down

the hall, but failed to see me hidden in the janitor's closet. Under each arm was a two-gallon can of

gasoline, in each hand another. He put down three of the cans and turned the last one upside down, then

walked down the hall, spreading a pungent trail of gasoline. His face was blank. When he started on the

second can, I figured it was about enough. As he passed my hiding spot, I walloped him over the head

with a wrench, and called hotel security. Then I went back to the closet and let the ripples of time

converge.

I arrived in a burning room, flames licking forth at me, the heat almost too much to bear. I gasped for

breath—a mistake—and punched at the keypad.

Notes on the Theory and Practice of Time Travel:

1. Travel is possible only into the past.

2. The object transported will return to exactly the time and place of departure.

3. It is not possible to bring objects from the past to the present.

4. Actions in the past cannot change the present.

ONE TIME I tried jumping back a hundred million years, to the Cretaceous, to see dinosaurs. All the

picture books show the landscape as being covered with dinosaurs. I spent three days wandering around

a swamp—in my new tweed suit—-before catching even a glimpse of any dinosaur larger than a basset

hound. That one—a theropod of some sort, I don't know which—skittered away as soon as it caught a

whiff of me. Quite a disappointment.

MY PROFESSOR in transfinite math used to tell stories about a hotel with an infinite number of rooms.

One day all the rooms are full, and another guest arrives. "No problem," says the desk clerk. He moves

the person in room one into room two, the person in room two into room three, and so on. Presto! A

vacant room.

A little later, an infinite number of guests arrive. "No problem," says the dauntless desk clerk. He moves

the person in room one into room two, the person in room two into room four, the person in room three

into room six, and so on. Presto! An infinite number of rooms vacant.

My time machine works on just that principle.

AGAIN I RETURN TO 1965, the fixed point, the strange attractor to my chaotic trajectory. In years of

wandering I've met countless people, but Daniel Ranien—Dancer—was the only one who truly had his

head together. He had a soft, easy smile, a battered secondhand guitar, and as much wisdom as it has

taken me a hundred lifetimes to learn. I've known him in good times and bad, in summer days with blue

skies that we swore would last a thousand years, in days of winter blizzards with drifted snow piled high

over our heads. In happier times we have laid roses into the barrels of rifles; we have laid our bodies

across the city streets in the midst of riots, and not been hurt. And I have been with him when he died,

once, twice, a hundred times over.

He died on February 8, 1969, a month into the reign of King Richard the Trickster and his court fool

Spiro, a year before Kent State and Altamont and the secret war in Cambodia slowly strangled the

summer of dreams. He died, and there was—is—nothing I can do. The last time he died I dragged him

to a hospital, where I screamed and ranted until finally I convinced them to admit him for observation,

though nothing seemed wrong with him. With X rays and arteriograms and radioactive tracers, they found

the incipient bubble in his brain; they drugged him, shaved his beautiful long brown hair, and operated on

him, cutting out the offending capillary and tying it off neatly. When the anesthetic wore off, I sat in the

hospital room and held his hand. There were big purple blotches under his eyes. He gripped my hand and

stared, silent, into space. Visiting hours or no, I didn't let them throw me out of the room. He just stared.

In the gray hours just before dawn he sighed softly and died. There was nothing at all that I could do.

TIME TRAVEL is subject to two constraints: conservation of energy, and causality. The energy to

appear in the past is only borrowed from the Dirac sea, and since ripples in the Dirac sea propagate in

the negative direction, transport is only into the past. Energy is conserved in the present as long as the

object transported returns with zero time delay, and the principle of causality assures that actions in the

past cannot change the present. For example, what if you went into the past and killed your father? Who,

then, would invent the time machine?

Once I tried to commit suicide by murdering my father, before he met my mother, twenty-three years

before I was born. It changed nothing, of course, and even when I did it, I knew it would change nothing.

But you have to try these things. How else could I know for sure?

NEXT WE TRIED sending a rat back. It made the trip through the Dirac sea and back undamaged.

Then we tried a trained rat, one we borrowed from the psychology lab across the green without telling

them what we wanted it for. Before its little trip it had been taught to run through a maze to get a piece of

bacon. Afterwards, it ran the maze as fast as ever.

We still had to try it on a human. I volunteered myself and didn't allow anyone to talk me out of it. By

trying it on myself, I dodged the university regulations about experimenting on humans.

The dive into the negative-energy sea felt like nothing at all. One moment I stood in the center of the loop

of Renselz coils, watched by my two grad students and a technician; the next I was alone, and the clock

had jumped back exactly one hour. Alone in a locked room with nothing but a camera and a clock, that

moment was the high point of my life.

The moment when I first met Dancer was the low point. I was in Berkeley, a bar called Trishia's, slowly

getting trashed. I'd been doing that a lot, caught between omnipotence and despair. It was 1967. 'Frisco

then—it was the middle of the hippy era—seemed somehow appropriate.

There was a girl, sitting at a table with a group from the university. I walked over to her table and invited

myself to sit down. I told her she didn't exist, that her whole world didn't exist, it was all created by the

fact that I was watching, and would disappear back into the sea of unreality as soon as I stopped

looking. Her name was Lisa, and she argued back. Her friends, bored, wandered off, and in a while Lisa

realized just how drunk I was. She dropped a bill on the table and walked out into the foggy night.

I followed her out. When she saw me following, she clutched her purse and bolted.

He was suddenly there under the streetlight. For a second I thought he was a girl. He had bright blue

eyes and straight brown hair down to his shoulders. He wore an embroidered Indian shirt, with a silver

and turquoise medallion around his neck and a guitar slung across his back. He was lean, almost stringy,

and moved like a dancer or a karate master. But it didn't occur to me to be afraid of him.

He looked me over. "That won't solve your problem, you know," he said.

And instantly I was ashamed. I was no longer sure exactly what I'd had in mind or why I'd followed her.

It had been years since I'd first fled my death, and I had come to think of others as unreal, since nothing I

could do would permanently affect them. My head was spinning. I slid down the wall and sat down,

hard, on the sidewalk. What had I come to?

He helped me back into the bar, fed me orange juice and pretzels, and got me to talk. I told him

everything. Why not, since I could unsay anything I said, undo anything I did? But I had no urge to. He

listened to it all, saying nothing. No one else had ever listened to the whole story before. I can't explain

the effect it had on me. For uncountable years I'd been alone, and then, if only for a moment… It hit me

with the intensity of a tab of acid. If only for a moment, I was not alone.

We left arm in arm. Half a block away, Dancer stopped, in front of an alley. It was dark.

"Something not quite right here." His voice had a puzzled tone.

I pulled him back. "Hold on. You don't want to go down there—" He pulled free and walked in. After a

slight hesitation, I followed.

The alley smelled of old beer, mixed with garbage and stale vomit. In a moment, my eyes became

adjusted to the dark.

Lisa was cringing in a corner behind some trash cans. Her clothes had been cut away with a knife, and

lay scattered around. Blood showed dark on her thighs and one arm. She didn't seem to see us. Dancer

squatted down next to her and said something soft. She didn't respond. He pulled off his shirt and

wrapped it around her, then cradled her in his arms and picked her up. "Help me get her to my

apartment."

"Apartment, hell. We'd better call the police," I said.

"Call the pigs? Are you crazy? You want them to rape her, too?"

I'd forgotten; this was the sixties. Between the two of us, we got her to Dancer's VW bug and took her

to his apartment in The Hash-bury. He explained it to me quietly as we drove, a dark side of the summer

of love that I'd not seen before. It was greasers, he said. They come down to Berkeley because they

heard that hippie chicks gave it away free, and get nasty when they met one who thought otherwise.

Her wounds were mostly superficial. Dancer cleaned her, put her in bed, and stayed up all night beside

her, talking and crooning and making little reassuring noises. I slept on one of the mattresses in the hall.

When I woke up in the morning, they were both in his bed. She was sleeping quietly. Dancer was awake,

holding her. I was aware enough to realize that that was all he was doing, holding her, but still I felt a

sharp pang of jealousy, and didn't know which one of them it was that I was jealous of.

Notes for a Lecture on Time Travel

The beginning of the twentieth century was a time of intellectual giants, whose likes will perhaps never

again be equaled. Einstein had just invented relativity, Heisenberg and Schrodinger quantum mechanics,

but nobody yet knew how to make the two theories consistent with each other. In 1930, a new person

tackled the problem. His name was Paul Dirac. He was twenty-eight years old. He succeeded where the

others had failed.

His theory was an unprecedented success, except for one small detail. According to Dirac's theory, a

particle could have either positive or negative energy. What did this mean, a particle of negative energy?

How could something have negative energy? And why don't ordinary—positive energy—particles fall

down into these negative energy states, releasing a lot of free energy in the process?

You or I might have merely stipulated that it was impossible for an ordinary positive energy particle to

make a transition to negative energy. But Dirac was not an ordinary man. He was a genius, the greatest

physicist of all, and he had an answer. If every possible negative energy state was already occupied, a

particle couldn't drop into a negative energy state. Ah ha! So Dirac postulated that the entire universe is

entirely filled with negative energy particles. They surround us, permeate us, in the vacuum of outer space

and in the center of the earth, every possible place a particle could be. An infinitely dense "sea" of

negative energy particles. The Dirac sea.

His argument had holes in it, but that comes later.

ONCE I WENT to visit the crucifixion. I took a jet from Santa Cruz to Tel Aviv, and a bus from Tel

Aviv to Jerusalem. On a hill outside the city, I dove through the Dirac sea.

I arrived in my three-piece suit. No way to help that, unless I wanted to travel naked. The land was

surprisingly green and fertile, more so than I'd expected. The hill was now a farm, covered with grape

arbors and olive trees. I hid the coils behind some rocks and walked down to the road. I didn't get far.

Five minutes on the road, I ran into a group of people. They had dark hair, dark skin, and wore clean

white tunics. Romans? Jews? Egyptians? How could I tell? They spoke to me, but I couldn't understand

a word. After a while two of them held me, while a third searched me. Were they robbers, searching for

money? Romans, searching for some kind of identity papers? I realized how naive I'd been to think I

could just find appropriate dress and somehow blend in with the crowds. Finding nothing, the one who'd

done the search carefully and methodically beat me up. At last he pushed me face down in the dirt. While

the other two held me down, he pulled out a dagger and slashed through the tendons on the back of each

leg. They were merciful, I guess. They left me with my life. Laughing and talking incomprehensibly among

themselves, they walked away.

My legs were useless. One of my arms was broken. It took me four hours to crawl back up the hill,

dragging myself with my good arm. Occasionally people would pass by on the road, studiously ignoring

me. Once I reached the hiding place, pulling out the Renselz coils and wrapping them around me was

pure agony. By the time I entered return on the keypad I was wavering in and out of consciousness. I

finally managed to get it entered. From the Dirac sea the ripples converged and I was in my hotel room in

Santa Cruz. The ceiling had started to fall in where the girders had burned through. Fire alarms shrieked

and wailed, but there was no place to run. The room was filled with dense, acrid smoke. Trying not to

breathe, I punched out a code on the keypad, somewhen, anywhen other than that one instant and I was

in the hotel room, five days before. I gasped for breath. The woman in the hotel bed shrieked and tried to

pull the covers up. The man screwing her was too busy to pay any mind. They weren't real anyway. I

ignored them and paid a little more attention to where to go next. Back to '65, I figured. I punched in the

combo and was standing in an empty room on the thirtieth floor of a hotel just under construction. A full

moon gleamed on the silhouettes of silent construction cranes. I flexed my legs experimentally. Already

the memory of the pain was beginning to fade. That was reasonable, because it had never happened.

Landis, Geoffrey A - SS - Ripples in the Dirac Sea.pdf

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