Michael Poole’s father, Harry, twinkled into existence in the middle of the Hermit Crab’s lifedome. Glimmering pixels cast highlights onto the bare domed ceiling before coalescing into a stocky, smiling, smooth-faced figure, dressed in a single-piece, sky-blue suit. "It’s good to see you, son. You’re looking well."

Michael Poole sucked on a bulb of malt whiskey and glowered at his father. The domed roof was opaqued, but the transparent floor revealed a plain of comet ice over which Harry seemed to hover, suspended. "Like hell I am," Michael growled. His voice, rusty after decades of near solitude out here in the Oort Cloud, sounded like gravel compared to his father’s smooth modulation. "I’m older than you."

Harry laughed and took a tentative step forward. "I’m not going to argue with that. But at least it’s your choice. You shouldn’t drink so early in the day, though."

The Virtual’s projection was slightly off, so there was a small, shadowless gap between Harry’s smart shoes and the floor; Michael smiled inwardly, relishing the tiny reminder of the unreality of the scene. "The hell with you. I’m two hundred and seven years old; I do what I please."

A look of sad affection crossed Harry’s brow. "You always did, son. I’m joking."

Michael took an involuntary step back from the Virtual; the adhesive soles of his shoes kept him locked to the floor in the weightless conditions of the lifedome. "What do you want here?"

"I want to give you a hug."

"Sure." Michael splashed whiskey over his fingertips and sprinkled droplets over the Virtual; golden spheres sailed through the image, scattering clouds of cubical pixels. "If that were true you’d be speaking to me in person, not through a Virtual reconstruct."

"Son, you’re four light-months from home. What do you want, a dialogue spanning the rest of our lives? Anyway, these modern Virtuals are so damned good." Harry had that old look of defensiveness in his blue eyes now, a look that took Michael all the way back to a troubled boyhood. Another justification, he thought. Harry had been a distant father, always bound up with his own projects — an irregular, excuse-laden intrusion into Michael’s life.

The final break had come when, thanks to AS, Michael had grown older than his father.

Harry was saying, "Virtuals like this one have passed all the Turing tests anyone can devise for them. As far as you’re concerned, Michael, this is me — Harry — standing here talking to you. And if you took the time and trouble you could send a Virtual back the other way."

"What do you want, a refund?"

"Anyway, I had to send a Virtual. There wasn’t time for anything else."

These words, delivered in an easy, matter-of-fact tone, jarred in Michael’s mind. "Wasn’t time? What are you talking about?"

Harry fixed him with an amused stare. "Don’t you know?" he asked heavily. "Don’t you follow the news?"

"Don’t play games," said Michael wearily. "You’ve already invaded my privacy. Just tell me what you want."

Instead of answering directly Harry gazed down through the clear floor beneath his feet. The core of a comet, a mile wide and bristling with ancient spires of ice, slid through the darkness; spotlight lasers from the Hermit Crab evoked hydrocarbon shades of purple and green. "Quite a view," Harry said. "It’s like a sightless fish, isn’t it? A strange, unseen creature sailing through the Solar System’s darkest oceans."

In all the years he’d studied the comet, that image had never struck Michael; hearing the words now he saw how right it was. But he replied heavily, "It’s just a comet. And this is the Oort Cloud. The cometary halo, a third of a light-year from the Sun; where all the comets come to die—"

"Nice place," Harry said, unperturbed. His eyes raked over the bare dome, and Michael abruptly felt as if he were seeing the place through his father’s eyes. The ship’s lifedome, his home for decades, was a half sphere a hundred yards wide. Couches, control panels, and basic data entry and retrieval ports were clustered around the geometric center of the dome; the rest of the transparent floor area was divided up by shoulder-high partitions into lab areas, a galley, a gym, a sleeping area, and a shower.

Suddenly the layout, Michael’s few pieces of furniture, the low single bed, looked obsessively plain and functional.

Harry walked across the clear floor to the rim of the lifedome; Michael, whiskey warming in his hand, joined him reluctantly. From here the rest of the Crab could be seen. A spine bristling with antennae and sensors crossed a mile of space to a block of Europa ice, so that the complete ship had the look of an elegant parasol, with the lifedome as canopy and the Europa ice as handle. The ice block — hundreds of yards wide when mined from Jupiter’s moon — was pitted and raddled, as if molded by huge fingers. The ship’s GUT drive was buried inside that block, and the ice had provided the ship’s reaction mass during Michael’s journey out here.

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 pixielike. 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 coloring — 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…