Timelike Infinity

by Stephen Baxter

  * * *

  "You were never happier than in those times, were you, Michael?" Harry asked, disconcertingly direct.

  Michael bit back a sharp, defensive reply. "It was my life's work."

  "I know it was. But it wasn't the end of your life."

  Michael gripped the whiskey globe harder, feeling its warm smoothness glide under his fingers. "It felt like it, when the Cauchy finally left Jupiter's orbit towing one of the Interface portals. I'd proved that exotic material was more than just a curiosity; that it could be made available for engineering purposes on the greatest of scales. But it was an experiment that was going to take a century to unfold—"

  "Or fifteen centuries, depending on your point of view."

  The Cauchy was dispatched on a long, near-lightspeed Jaunt in the direction of Sagittarius — toward the center of the Galaxy. It was to return after a subjective century of flight — but, thanks to time dilation effects, to a Solar System fifteen centuries older.

  And that was the purpose of the project.

  Michael had sometimes studied Virtuals of the wormhole portal left abandoned in Jovian orbit; it was aging at the same rate as its twin aboard the Cauchy, just as he and Miriam were. But while Miriam and Michael were separated by a growing "distance" in Einsteinian spacetime — a distance soon measured in lightyears and centuries — the wormhole still joined the two portals. After a century of subjective time, for both Michael and Miriam, the Cauchy would complete its circular tour and return to Jovian orbit, lost in Michael's future.

  And then it would be possible, using the wormhole, to step in a few hours across fifteen centuries of time.

  The departure of the ship, the waiting for the completion of the circuit, had left a hole in Michael's life, and in his heart.

  "I found I'd become an engineer rather than a scientist... I'd restricted my attention to the single type of material we could fabricate in our Io flux tube accelerators; the rest of exotic physics remained untouched. So I decided—"

  "To run away?"

  Again Michael was stabbed by anger.

  His father leaned forward from the chair, hands folded before him; the gray light from the comet below played over his clear, handsome face. The brandy glass was gone now, Michael noticed, a discarded prop. "Damn it, Michael; you had become a powerful man. It wasn't just science, or engineering. To establish and complete the Interface project you had to learn how to build with people. Politics. Budgets. Motivation. How to run things; how to manage — how to achieve things in a world of human beings. You could have done it again, and again; you could have built whatever you wanted to, having learned how.

  "And yet you turned away from it all. You ran and hid, out here. Look, I know how much it must have hurt, when Miriam Berg decided to fly out with the Cauchy rather than stay with you. But—"

  "I'm not hiding, damn you," Michael said, striving to mask a flare of anger. "I've told you what I'm doing out here. The quark nuggets could provide new insight into the fundamental structure of matter—"

  "You're a dilettante," Harry said, and he sat back in his chair dismissively. "That's all. You have no control over what comes wafting in to you from the depths of time and space. Sure, it's intriguing. But it isn't science. It's collecting butterflies. The big projects in the inner System, like the Serenitatis accelerator, left you behind years ago." Harry's eyes were wide and unblinking. "Tell me I'm wrong."

  Michael, goaded, threw his whiskey globe to the floor. It smashed against the clear surface, and the yellow fluid, pierced by comet light, gathered stickily around rebounding bits of glass. "What the hell do you want?"

  "You let yourself grow old, Michael," Harry said sadly. "Didn't you? And — worse than that — you let yourself stay old."

  "I stayed human," Michael growled. "I wasn't going to have my head dumped out into a chip."

  Harry got out of his chair and approached his son. "It isn't like that," he said softly. "It's more like editing your memories. Classifying, sorting. Rationalizing."

  Michael snorted. "What a disgusting word that is."

  "Nothing's lost, you know. It's all stored — and not just on chips, but in neural nets you can interrogate — or use to feed Virtuals, if you like." Harry smiled. "You can talk to your younger self. Sounds like your ideal occupation, actually."

  "Look." Michael closed his eyes and pressed his fingers against the bridge of his nose. "I've thought through all of this. I've even discussed it with you before. Or have you forgotten that too?"

  "There isn't really a choice, you know."

  "Of course there is."

  "Not if you want to stay human, as you say you do. Part of being human is to be able to think fresh thoughts — to react to new people, new events, new situations. Michael, the fact is that human memory has a finite capacity. The more you cram in there the longer the retrieval times become. With AS technology—"

  "You can't make yourself a virgin by transplanting a hymen, for God's sake."

  "You're right." Harry reached out a hand to his son — then hesitated and dropped it again. "Coarse, as usual, but correct. And I'm not telling you that tidying up your memories is going to restore your innocence. Your thrill at first hearing Beethoven. The wonder of your first kiss. And I know you're frightened of losing what you have left of Miriam."

  "You presume a hell of a lot, damn you."

  "But, Michael — there isn't an option. Without it, there's only fossilization." Harry smiled ruefully. "I'm sorry, son. I didn't mean to tell you how to run your life."

  "No. You never did, did you? It was always just a kind of habit." Michael crossed to a serving hatch and, with rapid taps at a keypad icon, called up another whiskey. "Tell me what was so urgent that you had to beam out a Virtual package."

  Harry paced slowly across the clear floor; his silent footsteps, weight-laden in the absence of gravity and suspended over the ocean of space, gave the scene an eerie aspect. "The Interface," he said.

  Michael frowned. "The project? What about it?"

  Harry considered his son with genuine sympathy. "I guess you really have lost track of your life, out here. Michael, it's a century now since the launch of the Cauchy. Don't you recall the mission plan?"

  Michael thought it over. A century—

  "My God," Michael said. "It's time, isn't it?"

  The Cauchy should have returned to Sol, in that remote future. Michael cast an involuntary glance up at the cabin wall, in the direction of Jupiter. The second wormhole portal still orbited Jupiter patiently; was it possible that — even now — a bridge lay open across a millennium and a half?

  "They sent me to fetch you," Harry was saying ruefully. "I told them it was a waste of time, that we'd argued since you were old enough to talk. But they sent me anyway. Maybe I'd have a better chance of persuading you than anybody else."

  Michael felt confused. "Persuading me to do what?"

  "To come home." The Virtual glanced around the cabin. "This old tub can still fly, can't she?"

  "Of course she can."

  "Then the quickest way for you to return is to come in voluntarily in this thing. It will take you about a year. It would take twice as long to send a ship out to fetch you—"

  "Harry. Slow down, damn it. Who are 'they'? And why am I so important, all of a sudden?"

  " 'They' are the Jovian government. And they have the backing of all the intergovernmental agencies. System-wide, as far as I know. And you're important because of the message."

  "What message?"

  Harry studied his son, his too young face steady, his voice level. "Michael, the portal has returned. And something's emerged from the wormhole. A ship from the future. We've had one message from it, on microwave wavelengths; we suspect the message was smuggled out, against the will of whoever's operating the ship."

  Michael shook his head. Maybe he had let himself get too old; Harry's words seemed unreal — like descriptions of a dream, impossible to comprehend. "Could the message be translated?"
<
br />   "Fairly easily," said Harry dryly. "It was in English. Voice, no visual."

  "And? Come on, Harry."

  "It asked for you. By name. It was from Miriam Berg."

  Michael felt the breath seep out of him, against his will.

  His father's Virtual crouched before him, one hand extended, close enough to Michael's face for him to make out individual pixels. "Michael? Are you all right?"

  Chapter 3

  AGAIN JASOFT PARZ WAS SUSPENDED in space before a Spline ship.

  The freighter was a landscape of gray flesh. Parz peered into an eyeball that, swiveling, gazed out at him from folds of hardened epidermis, and Parz felt a strange sense of kinship with the Spline, this fellow client creature of the Qax.

  Parz was aware of a hundred weapons trained upon his fragile flitter — perhaps including, even, the fabled gravity-wave starbreaker beams, purloined by the Qax from the Xeelee.

  He wanted to laugh. A wall of nonexistence was, perhaps, hurtling toward them from out of the altered past, and yet still they brandished their toy weapons against an old man.

  "Ambassador Jasoft Parz." The Governor's translated voice was, as ever, soft, feminine, and delicious, and quite impossible to read.

  Parz kept his voice steady. "I am here, Governor."

  There was a long silence. Then the Governor said, "I must ask your help."

  Parz felt a kind of tension sag out of him, and it was as if the muscles of his stomach were folding over each other. How he had dreaded this call to meet with the Governor — his first journey into orbit since that fateful moment a week earlier when he had been forced to witness the humiliation of the Qax at the hands of the rebellious rabble who had escaped through the Interface portal. Parz had returned to his normal duties — though that had been difficult enough; even the rarefied diplomatic circles that controlled the planet were alive with talk of that single, staggering act of defiance. At times Parz had longed to walk away from the heavy cordon of security that surrounded his life and immerse himself in the world of the common man. He would be destroyed as soon as they discovered he was a collaborator, of course... but maybe it would be worth it, to hear the delicious note of hope on a thousand lips.

  But he had not the courage, or the foolhardiness, to do any such thing. Instead, he had waited for the Governor to decide what to do. It would be quite within the imagination of the Qax to find a way to punish the planet as a whole for the actions of a few individuals.

  Deaths would not have surprised Parz.

  Paradoxically he had always found it hard to blame the Qax for this sort of action. To establish control of Earth and its sister worlds the Qax had merely had to study history and adapt methods used by humans to oppress their fellows. There was no evidence that the Qax had ever evolved such tactics as means of dealing with each other. The Qax were acting as had oppressors throughout human history, Parz thought, but still humanity had only itself to blame; it was as if the Qax were an externalized embodiment of man's treatment of man, a judgment of history.

  But, in the event, nothing of the sort had happened. And now Parz had been called to another secure orbital meeting.

  "Tell me what you want, Governor."

  "We believe we have made the Interface portal secure," the Qax began. "It is ringed by Spline warships. Frankly, any human who ventures within a million miles of the artifact will be discontinued."

  Parz raised his eyebrows. "I'm surprised you've not destroyed the portal."

  Again that uncharacteristic hesitation. "Jasoft Parz, I find myself unable to determine the correct course of action. A human vessel, manned by rebels against the Qax administration, has escaped fifteen centuries into the past — into an era in which the Qax had no influence over human affairs. The intention of these rebels is surety to change the evolution of events in some way, presumably to prepare humanity to resist, or throw off, the Qax administration.

  "Parz, I have to assume that the past has already been altered by these rebels."

  Parz nodded. "And were you to destroy the portal you would lose the only access you have to the past."

  "I would lose any possible control over events. Yes."

  Parz shifted his position in his chair. "And have you sent anything through?"

  "Not yet."

  Parz laughed. "Governor, it's been a week. Don't you think you're being a little indecisive? Either close the damn thing or use it; one way or the other you're going to have to act."

  And all the time you procrastinate, he added silently, the wall of unreality approaches us all at an unknowable speed...

  Parz expected a harsh reply to his goad, but instead there was again that hesitancy. "I find myself unable to formulate a plan of action. Ambassador, consider the implications. These human rebels control history, over one and a half thousand years. I have tried to evaluate the potential for damage implied by this, but no algorithm has been able to deliver even an order-of-magnitude assessment. I believe the danger is — in practical terms — infinite... My race has never faced such a threat, and perhaps never will again."

  Jasoft pulled at his lip. "I almost sympathize with you, Governor."

  There had been a flurry of speculation about the effects of the rebels' escape into the past among what was left of the human scientific community too. Could the rebels truly alter history? Some argued that their actions would only cause a broadening of probability functions — that new alternate realities were being created by their actions. Others maintained that reality had only a single thread, opened to disruption by the creation of the rebels' "closed timelike curve," their path through spacetime into the past.

  In either event, no one knew whether consciousness could persist through such a disruption — would Jasoft know if the world, his own history, altered around him? Or would he go through a minideath, to be replaced by a new, subtly adjusted Jasoft? Nor were there any estimates of the rate — in subjective terms — at which the disruption was approaching, emerging from the past as if from the depths of some dismal sea.

  To Jasoft such speculation seemed unreal — and yet it also lent an air of unreality to the world he inhabited, as if his life were all no more than a brightly painted surface surrounding a vacuum. He wasn't afraid — at least he didn't think so — but he sensed that his grip on reality had been disturbed, fundamentally.

  It was like, he suspected, becoming mildly insane.

  "Ambassador, report on what you have determined about the rebels."

  Jasoft pulled his slate from his briefcase, set it up on the tabletop before him, and ran his fingers over its surface, drawing data from its heart. "We believe the rebels constitute a group calling themselves the Friends of Wigner. Before this single, astonishing action, the Friends were dismissed as a fringe sect of no known danger to the regime."

  "We have a conscious policy of ignoring such groups," the Qax said grimly. "Adapted from the policies of such human colonial powers as the Roman Empire, who allowed native religions to flourish... Why waste effort suppressing that which is harmless? Perhaps this policy will have to be reviewed."

  Parz found himself shuddering at the menace implicit in that last, lightly delivered sentence. "I'd advise against it," he said quickly. "After all, as you say, the damage is already done."

  "What is known of the vessel?"

  Jasoft reported that the craft had been assembled underground on the small offshore island still called Britain.

  During the decades of the Occupation there had been a program to remove human capacity for space travel, and systematically, ships from all over the Solar System and from the nearby stars — the small bubble of space embraced by humans before the Occupation — had been recalled, impounded, and broken up in shipyards converted to crude wrecking shops. Nobody knew, even now, how many lone craft there were still avoiding the law of the Qax somewhere between the stars, but with the Solar System and the major extra-Solar colonies invested, they could do little damage.

  ...Until now. The rebel craft ha
d apparently been constructed around the purloined remains of a broken, impounded freighter.

  "And why the name?" the Qax asked. "Who was this Wigner?"

  Parz tapped his slate. "Eugene Wigner. A quantum physicist of the twentieth century: a near contemporary of the great pioneers of the field — Schrödinger, Heisenberg. Wigner's subject was quantum solipsism."

  There was a brief silence from the Qax. Then: "That means little to me. We must determine the intentions of these Friends, Jasoft; we must find a way to see through their human eyes. I am not human. You must help me."

  Parz spread his hands on the tabletop and gathered his thoughts.

  Wigner and his coworkers had tried to evolve a philosophy in response to the fact that quantum physics, while universally accepted, was saturated with dazzling paradoxes that suggested that the external world had no well-defined structure until minds observed it.

  "We humans are a finite, practical species," Jasoft said. "I live in my head, somewhere behind my eyes. I have intimate control over my body — my hands, my feet — and some control over objects I can pick up and manipulate." He held his slate in his hands. "I can move the slate about; if I throw it against the wall it bounces off. The slate is discrete in itself and separate from me."

  But this commonsense view of the universe began to fall apart as one approached the smallest scales of creation.

  "Uncertainty is at the heart of it. I can measure the position of my slate by, say, bouncing a photon off it and recording the event in a sensor. But how do I record the position of an electron? If I bounce off a photon, I knock the electron away from where I measured it... Suppose I measured the electron's position to within a billionth of an inch. Then my uncertainty about the electron's momentum would be so high that a second later I couldn't be sure where the damn thing was to within a hundred miles.

  "So I can never be simultaneously sure where an electron is and where it's going... Instead of thinking of an electron, or any other object, as a discrete, hard little entity, I have to think in terms of probability wave functions."