The Time Traveler's Almanac (7 page)

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 naïve 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 a 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. Time travel. It’s not immortality, but it’s got to be the next best thing.

You can’t change the past, no matter how you try.

*   *   *

In the morning I explored Dancer’s pad. It was crazy, a small third-floor apartment a block off Haight Ashbury that had been converted into something from another planet. The floor of the apartment had been completely covered with old mattresses, on top of which was a jumbled confusion of quilts, pillows, Indian blankets, stuffed animals. You took off your shoes before coming in – Dancer always wore sandals, leather ones from Mexico with soles cut from old tires. The radiators, which didn’t work anyway, were spray-painted in dayglo colors. The walls were plastered with posters: Peter Max prints, brightly colored Eschers, poems by Allen Ginsberg, record album covers, peace rally posters, a “Haight is Love” sign, FBI ten most-wanted posters torn down from a post office with photos of famous antiwar activists circled in blue magic-marker, a huge peace symbol in passion-pink. Some of the posters were illuminated with black light and luminesced in impossible colors. The air was musty with incense and the banana-sweet smell of dope. In one corner a record player played
Sergeant Pepper’s Lonely Hearts Club Band
on infinite repeat. Whenever one copy of the album got too scratchy, inevitably one of Dancer’s friends would bring in another. He never locked the door. “Somebody wants to rip me off, well, hey, they probably need it more than I do anyway, okay? It’s cool.” People dropped by any time of day or night.

I let my hair grow long. Dancer and Lisa and I spent that summer together, laughing, playing guitar, making love, writing silly poems and sillier songs, experimenting with drugs. That was when LSD was blooming onto the scene like sunflowers, when people were still unafraid of the strange and beautiful world on the other side of reality. That was a time to live. I knew that it was Dancer that Lisa truly loved, not me, but in those days free love was in the air like the scent of poppies, and it didn’t matter. Not much, anyway.

NOTES FOR A LECTURE ON TIME TRAVEL (continued)

Having postulated that all of space was filled with an infinitely dense sea of negative energy particles, Dirac went on further and asked if we, in the positive-energy universe, could interact with this negative energy sea. What would happen, say, if you added enough energy to an electron to take it out of the negative energy sea? Two things: first, you would create an electron, seemingly out of nowhere. Second, you would leave behind a “hole” in the sea. The hole, Dirac realized, would act as if it were a particle itself, a particle exactly like an electron except for one thing: it would have the opposite charge. But if the hole ever encountered an electron, the electron would fall back into the Dirac sea, annihilating both electron and hole in a bright burst of energy. Eventually they gave the hole in the Dirac sea a name of its own: “positron.” When Anderson discovered the positron two years later to vindicate Dirac’s theory, it was almost an anticlimax.

And over the next fifty years, the reality of the Dirac sea was almost ignored by physicists. Antimatter, the holes in the sea, was the important feature of the theory; the rest was merely a mathematical artifact.

Seventy years later, I remembered the story my transfinite math teacher told and put it together with Dirac’s theory. Like putting an extra guest into a hotel with an infinite number of rooms, I figured out how to borrow energy from the Dirac sea. Or, to put it another way: I learned how to make waves.

And waves on the Dirac sea travel backward in time.

Next we had to try something more ambitious. We had to send a human back farther into history, and obtain proof of the trip. Still we were afraid to make alterations in the past, even though the mathematics stated that the present could not be changed.

We pulled out our movie camera and chose our destinations carefully.

In September of 1853 a traveller named William Hapland and his family crossed the Sierra Nevadas to reach the California coast. His daughter Sarah kept a journal, and in it she recorded how, as they reached the crest of Parker’s ridge, she caught her first glimpse of the distant Pacific ocean exactly as the sun touched the horizon, “in a blays of cryms’n glorie,” as she wrote. The journal still exists. It was easy enough for us to conceal ourselves and a movie camera in a cleft of rocks above the pass, to photograph the weary travellers in their ox-drawn wagon as they crossed.

The second target was the great San Francisco earthquake of 1906. From a deserted warehouse that would survive the quake – but not the following fire – we watched and took movies as buildings tumbled down around us and embattled firemen in horse-drawn firetrucks strove in vain to quench a hundred blazes. Moments before the fire reached our building, we fled into the present.

The films were spectacular.

We were ready to tell the world.

There was a meeting of the AAAS in Santa Cruz in a month. I called the program chairman and wangled a spot as an invited speaker without revealing just what we’d accomplished to date. I planned to show those films at the talk. They were to make us instantly famous.

*   *   *

The day that Dancer died we had a going-away party, just Lisa and Dancer and I. He knew he was going to die; I’d told him and somehow he believed me. He always believed me. We stayed up all night, playing Dancer’s second-hand mandolin, painting psychedelic designs on each other’s bodies with grease-paint, competing against each other in a marathon game of cut-throat Monopoly, doing a hundred silly, ordinary things that took meaning only from the fact that it was the last time. About four in the morning, as the glimmer of false-dawn began to show in the sky, we went down to the bay and, huddling together for warmth, went tripping. The last thing he said, he told us not to let our dreams die; to stay together.

We buried Dancer, at city expense, in a welfare grave. We split up three days later.

I kept in touch with Lisa, vaguely. In the late seventies she went back to school, first for an MBA, then law school. I think she was married for a while. We wrote each other cards at Christmas for a while, then I lost track of her. Years later I got a letter from her. She said that she was finally able to forgive me for causing Dan’s death.

It was a cold and foggy February day, but I knew I could find warmth in 1965. The ripples converged.

ANTICIPATED QUESTIONS FROM THE AUDIENCE:

Q (old, stodgy professor): It seems to me this proposed temporal jump of yours violates the law of conservation of mass/energy. For example, when a transported object is transported into the past, a quantity of mass will appear to vanish from the present, in clear violation of the conservation law.

A (me): Since the return is to the exact time of departure, the mass present is constant.

Q: Very well, but what about the arrival in the past? Doesn’t this violate the conservation law?

A: No. The energy needed is taken from the Dirac sea, by the mechanism I explain in detail in the Phys Rev paper. When the object returns to the “future,” the energy is restored to the sea.

Q (intense young physicist): Then doesn’t Heisenberg uncertainty limit the amount of time that can be spent in the past?

A: A good question. The answer is yes, but because we borrow an infinitesimal amount of energy from an infinite number of particles, the amount of time spent in the past can be arbitrarily large. The only limitation is that you must leave the past an instant before you depart from the present.

In half an hour I was scheduled to present the paper that would rank my name with Newton’s and Galileo’s – and Dirac’s. I was twenty-eight years old, the same age that Dirac was when he announced his theory. I was a firebrand, preparing to set the world aflame. I was nervous, rehearsing the speech in my hotel room. I took a swig out of an old Coke that one of my grad students had left sitting on top of the television. The evening news team was babbling on, but I wasn’t listening.

I never delivered that talk. The hotel had already started to burn; my death was already foreordained. Tie neat, I inspected myself in the mirror, then walked to the door. The doorknob was warm. I opened it onto a sheet of fire. Flame burst through the opened door like a ravening dragon. I stumbled backward, staring at the flames in amazed fascination.

Somewhere in the hotel I heard a scream, and all at once I broke free of my spell. I was on the thirtieth story; there was no way out. My thought was for my machine. I rushed across the room and threw open the case holding the time machine. With swift, sure fingers I pulled out the Renselz coils and wrapped them around my body. The carpet had caught on fire, a sheet of flame between me and any possible escape. Holding my breath to avoid suffocation, I punched an entry into the keyboard and dove into time.

I return to that moment again and again. When I hit the final key, the air was already nearly unbreathable with smoke. I had about thirty seconds left to live, then. Over the years I’ve nibbled away my time down to ten seconds or less.

I live on borrowed time. So do we all, perhaps. But I know when and where my debt will fall due.

*   *   *

Dancer died on February 9, 1969. It was a dim, foggy day. In the morning, he said he had a headache. That was unusual, for Dancer never had headaches. We decided to go for a walk through the fog. It was beautiful, as if we were alone in a strange, formless world. I’d forgotten about his headache altogether, until, looking out across the sea of fog from the park over the bay, he fell over. He was dead before the ambulance came. He died with a secret smile on his face. I’ve never understood that smile. Maybe he was smiling because the pain was gone.

Lisa committed suicide two days later.

You ordinary people, you have the chance to change the future. You can father children, write novels, sign petitions, invent new machines, go to cocktail parties, run for president. You affect the future with everything you do. No matter what I do, I cannot. It is too late for that, for me. My actions are written in flowing water. And having no effect, I have no responsibilities. It makes no difference what I do, not at all.

When I first fled the fire into the past, I tried everything I could to change it. I stopped the arsonist, I argued with mayors, I even went to my own house and told myself not to go to the conference.

But that’s not how time works. No matter what I do, talk to a governor or dynamite the hotel, when I reach that critical moment – the present, my destiny, the moment I left – I vanish from whenever I was, and return to the hotel room, the fire approaching ever closer. I have about ten seconds left. Every time I dive through the Dirac sea, everything I changed in the past vanishes. Sometimes I pretend that the changes I make in the past create new futures, though I know this is not the case. When I return to the present, all the changes are wiped out by the ripples of the converging wave, like erasing a blackboard after a class.

Someday I will return and meet my destiny. But for now, I live in the past. It’s a good life, I suppose. You get used to the fact that nothing you do will ever have any effect on the world. It gives you a feeling of freedom. I’ve been places no one has ever been, seen things no one alive has ever seen. I’ve given up physics, of course. Nothing I discover could endure past that fatal night in Santa Cruz. Maybe some people would continue for the sheer joy of knowledge. For me, the point is missing.