Harry ducked his head, searching the stars. ‘Can I see Earth?’
Michael shrugged. ‘From here the inner Solar System is a muddy patch of light. Like a distant pond. You need instruments to make out Earth.’
‘You’ve left yourself a long way from home.’
Harry’s hair had been AS-restored to a thick blond mane; his eyes were clear blue stars, his face square, small-featured - almost pixie-like. Michael, staring curiously, was struck afresh at how young his father had had himself remade to look. Michael himself had kept the sixty-year-old body the years had already stranded him in when AS technology had emerged. Now he ran an unconscious hand over his high scalp, the tough, wrinkled skin of his cheeks. Damn it, Harry hadn’t even kept the colouring - the black hair, brown eyes - which he’d passed on to Michael.
Harry glanced at Michael’s drink. ‘Quite a host,’ he said, without criticism in his voice. ‘Why don’t you offer me something? I’m serious. You can buy Virtual hospitality chips now. Bars, kitchens. All the finest stuff for your Virtual guests.’
Michael laughed. ‘What’s the point? None of it’s real.’
For a second his father’s eyes narrowed. ‘Real? Are you sure you know what I’m feeling, right now?’
‘I don’t give a damn one way or the other,’ said Michael calmly.
‘No,’ Harry said. ‘I believe you really don’t. Fortunately I came prepared.’ He snapped his fingers and a huge globe of brandy crystallized in his open palm; Michael could almost smell its fumes. ‘Bit like carrying a hip flask. Well, Michael, I can’t say this is a pleasure. How do you live in this godforsaken place?’
The sudden question made Michael flinch, physically. ‘I’ll tell you how, if you like. I process comet material for food and air; there is plenty of carbohydrate material, and nitrogen, locked in the ice; and I—’
‘So you’re a high-tech hermit. Like your ship. A hermit crab, prowling around the rim of the Solar System, too far from home even to talk to another human being. Right?’
‘There are reasons,’ Michael said, trying to keep self-justification out of his voice. ‘Look, Harry, it’s my job. I’m studying quark nuggets—’
Harry opened his mouth; then his eyes lost their focus for a moment, and it was as if he were scanning some lost, inner landscape. At length he said with a weak smile: ‘Apparently I used to know what that meant.’
Michael snorted with disgust. ‘Nuggets are like extended nucleons—’
Harry’s smile grew strained. ‘Keep going.’
Michael talked quickly, unwilling to give his father any help.
Nucleons, protons and neutrons were formed from combinations of quarks. Under extremes of pressure - at the heart of a neutron star, or during the Big Bang itself - more extended structures could form. A quark nugget, a monster among nucleons, could mass a ton and be a thousandth of an inch wide . . .
Most of the nuggets from the Big Bang had decayed. But some survived.
‘And this is why you need to live out here?’
‘The first the inner Solar System knows of the presence of a nugget is when it hits the top of an atmosphere, and its energy crystallizes into a shower of exotic particles. Yes, you can learn something from that - but it’s like watching shadows on the wall. I want to study the raw stuff. And that’s why I’ve come so far out. Damn it, there are only about a hundred humans further from the Sun, and most of them are light-years away, in starships like the Cauchy, crawling at near-lightspeed to God knows where. Harry, a quark nugget sets up a bow wave in the interstellar medium. Like a sparkle of high-energy particles, scattered ahead of itself. It’s faint, but my detectors can pick it up, and - maybe one time out of ten - I can send out a probe to pick up the nugget itself.’
Harry tugged at the corner of his mouth - a gesture which reminded Michael jarringly of the frail eighty-year-old who had gone for ever. ‘Sounds terrific,’ Harry said. ‘So what?’
Michael bit back an angry response. ‘It’s called basic research,’ he said. ‘Something we humans have been doing for a couple of thousand years now—’
‘Just tell me,’ Harry said mildly.
‘Because quark nuggets are bundles of matter pushed to the extreme. Some can be moving so close to lightspeed that, thanks to time dilation, they reach my sensors barely a million subjective years after leaving the singularity itself.’
‘I guess I’m impressed.’ Harry sucked on his brandy, turned and walked easily across the transparent floor, showing no signs of vertigo or distraction. He reached a metal chair, sat on it and crossed his legs comfortably, ignoring the zero-gravity harness. The illusion was good this time, with barely a thread of space between the Virtual’s thighs and the surface of the chair. ‘I always was impressed with what you achieved. You, with Miriam Berg, of course. I’m sure you knew that, even if I didn’t say it all that often.’
‘No, you didn’t.’
‘Even a century ago you were the authority on exotic matter. Weren’t you? That was why they gave you such responsibility on the Interface project.’
‘Thanks for the pat on the head.’ Michael looked into the sky-blue emptiness of his father’s eyes. ‘Is that what you’ve come to talk about? What did you retain when you had your head cleaned out? Anything?’
Harry shrugged. ‘What I needed. Mostly stuff about you, if you want to know. Like a scrapbook . . .’
He sipped his drink, which glowed in the light of the comet, and regarded his son.
Wormholes are flaws in space and time which connect points separated by light-years - or by centuries - with near-instantaneous passages of curved space. They are useful . . . but difficult to build.
On the scale of the invisibly small - on Planck lengthscales, in which the mysterious effects of quantum gravity operate - spacetime is foamlike, riddled with tiny wormholes. Michael Poole and his team, a century earlier, had pulled such a wormhole out of the foam and manipulated its mouths, distorting it to the size and shape they wanted.
Big enough to take a spacecraft.
That was the easy part. Now they had to make it stable.
A wormhole without matter in its throat- a ‘Schwarzschild’ solution to the equations of relativity - is unusable. Lethal tidal forces would bar the wormhole portals, the portals themselves would expand and collapse at lightspeed, and small perturbations caused by any infalling matter would result in instability and collapse.
So Poole’s team had had to thread their wormhole with ‘exotic’ matter.
Space contracted towards the centre of the throat and then had to be made to expand again. A repulsive effect in the throat had come from exoticity, the negative energy density of the exotic matter. The wormhole was still intrinsically unstable, even so; but with feedback loops it could be made self-regulating.
At one time negative energy had been thought impossible. Like negative mass, the concept seemed intuitively impossible. But there had been encouraging examples for Michael and his team. Hawking evaporation of a black hole was a kind of mild exoticity ... But the negative energy levels Poole had needed were high, equivalent to the pressure at the heart of a neutron star.
It had been a challenging time.
Despite himself Michael found memories of those days filling his head, more vivid than the image of the washed-out lifedome, the imperfect one of his father. Why was it that old memories were so compelling? Michael and his team - including Miriam, his deputy - had spent more than forty years in a slow orbit around Jupiter; the exotic-matter process had depended on the manipulation of the energies of the magnetic flux tube which connected Jupiter to its moon, Io. Life had been hard, dangerous - but never dull. As the years had worn away they had watched again and again as the robot probes dipped into Jupiter’s gravity well and returned with another holdful of shining exotic material, ready to be plated over the growing tetrahedra of the portals.
It had been like watching a child grow.
Miriam and he had grown to depend on each other, c
ompletely, without question. Sometimes they had debated if this dependence contained the germ of love. Mostly, though, they had been too busy.
‘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 whisky 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 - towards the centre 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 light-years 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 fluxtube 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 grey 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 whisky 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 the contents of 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 whisky. ‘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 quality. ‘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 than anybody else of persuading you.’
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 somethin
g’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?’
‘Fairly easily,’ said Harry drily. ‘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?’
3
Again Jasoft Parz was suspended in space before a Spline ship. The freighter was a landscape of grey flesh. Parz peered into an eyeball which, swivelling, 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 even including the fabled gravity-wave starbreaker beams, purloined by the Qax from the Xeelee.
He wanted to laugh. A wall of non-existence was, perhaps, hurtling towards 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.’
Xeelee: An Omnibus: Raft, Timelike Infinity, Flux, Ring Page 28
