Geoffrey A. Landis, who appears later in this anthology with “At Dorado,” is a NASA scientist whose first novel, Mars Crossing, was published by Tor Books in 2000, winning a Locus Award. He has also won the Analog Analytical Laboratory Award for the novelette The Man in the Mirror (2009). A short-story collection, Impact Parameter and Other Quantum Realities, was published by Golden Gryphon Press in 2001. His 2010 novella The Sultan of the Clouds won the Sturgeon award for best short science fiction story. “Ripples in the Dirac Sea” was first published in Asimov’s Science Fiction Magazine in 1988 and won the 1989 Nebula Award for best short story.
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 between 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 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 blonde 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 even catching 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 that had 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 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 grey 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 in 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?