“The drinks will save the day,” Bram said. “And the eats. I’ve raided the buffet twice. Do I recognize Marg’s hand in those swirled yolk things?”
“Oh, it’s just something I whipped up for the culinary development department,” Marg said, touching her hair. Orris beamed.
Bram listened with half an ear while Orris rambled on about Marg’s triumphs. They’d given her a facility in the trunk so that she could experiment with zero-gravity cooking. Under those conditions, one could do amazing things with puff pastry and heat transfer. By the time they arrived at Juxt One, Marg would be the system’s expert on it.
Kerthin was nowhere in sight. She had drifted off earlier after a minimum exchange of conversation with Marg and Orris. Perhaps she had found a planetside acquaintance in the mob, or found a volunteer to take her exploring in some of the side tunnels. Quite a few of the visitors were doing that.
A few feet away, Smeth was holding forth to a captive audience that included Trist and his colonist friend, Jao. Jao was one of the red, hairy types that seemed to be popping up with increasing frequency in this generation after having been buried in the master genome for so long.
“You picked the wrong time to quit the project, Jao, old son,” Smeth said. “We’re on the verge of great things. The hadronic photon theory that our team tossed into the ring is going to mean a real breakthrough in developing a star drive, and the Nar know it. They’re inclined to give us more resources and step up the pace of the project now.”
He gave a toothy smile, then spoiled the effect of superiority by scratching his ribs. Smeth had regrown his beard since Bram had last seen him; it made a fuzzy round pompon on Smeth’s chin, a pompon that despite Smeth’s youth had an unexpected streak of gray in it that must have pleased him. Otherwise, Smeth hadn’t changed much, except that his gangling frame now carried a small potbelly.
“The hadronic photon came out of Jao’s work on photon-proton absorption, remember?” Trist put in mildly.
“Never mind, Trist,” Jao said with a large gesture of a furry forearm. “The project can have my little share of glory, and welcome to it!”
“That’s what I don’t understand,” Smeth said. “Giving it all up to go to Juxt One and become a —”
“A brewmaster,” Jao finished for him. “There’s always work for a good brewmaster anywhere in the known universe.” He gave them a wide grin through his red whiskers. “Regular hours and all the brew you can drink.”
In the crowd past Smeth’s cozy little coterie, Bram caught sight of Mim. How long had it been since he’d seen her? And even then it had been at one of her concerts; intimidated by the swarm of close friends and admirers around her, he hadn’t gone backstage to talk to her after the performance.
Her freshness and energy had always been attractive, but the past few years had given her beauty. Cheekbones, wide and explicit, had carved themselves into the roundness of her face. Her eyes were dark and huge and knew more. She had let her choppy black hair grow, and it hung past the line of her jaw, framing her face. Bram thought she looked a little sad.
Olan Byr was not with her. He had been in poor health lately, so the story went, and his virtuoso concerts were few and far between these days.
“And Marg’s pregnant, too, did you know that?” Orris was saying in his ear. “They’ve frozen the blastocyst for us, and she’s going to have it reimplanted when we go back down to the surface for the predeparture leave. The pronuclei were three-quarters ours — the rules for Juxt One are a bit more relaxed.”
“And the baby will be born between the stars,” Marg said. “It’s so poetic.”
There were coos of approval from two women whom Marg had collected into her orbit while Bram’s attention had wandered. A man with one of them said, “Juxt One needs humans; I’d go myself if I were younger.” When the conversation grew general, Bram slipped away without being noticed.
Mim was standing alone when Bram came up to her. The young man to whom she had been talking had been pulled away by two people, tree dwellers by the evidence of their bare feet, who wanted to show him something. “Hello, Mim,” Bram said.
She looked up, and her new molded face broke into the old Mim’s unaffected smile, washing away the tired lines he had seen there. “Hello, Bram.”
“It’s been a long time.”
“Yes, it has.” They raised hands and touched palms. “What are you doing here?”
“Orris and Marg invited me. You remember Orris?”
“Always borrowing things. Yes. I hope Marg is feeding him.”
“No fear on that score.” They looked at each other’s faces. “You’re not sailing to Juxt One, are you?”
She laughed. “No, I came to see friends off, too. We’re exporting a whole string quartet. They’ve never seen the real thing with the friction wand out there. They’ve just heard transmissions. The music department there issued an invitation that was hard to resist. Four of our young students decided to take advantage of it. That was one of them you saw me talking to.”
“How’s Olan?”
She bit her lip. “Not very well. He wanted to come with me today, but he wasn’t up to it.”
“I’m sorry to hear that. Please give him my best.”
“Thank you.” She tossed her head. “Are you still dreaming your magnificent dreams? About sailing between the galaxies and finding the worlds of Original Man?”
Bram smiled at the memory. “I guess I’ve become more down-to-earth over the years. It seems magnificent enough to be sending a string quartet to a star that’s a whole light-year away.”
“We’re all getting older,” she said sadly.
Yes, he thought. That was the crux of the matter. Mortality. That was the true obstacle to dreams like the one he’d had. You never thought about mortality when you were a child. Time and distance had been the enemies then.
Bram thought of Olan Byr and felt pity for him. And for Mim and himself and everybody else. The string quartet would spend their youth traveling to Juxt One. Marg and Orris would spend their baby’s childhood. They’d decided the bargain was worth it. But in every life there was only so much to spend.
“The dreams get more practical over the years,” he said lightly. “I’m quite happy to be working on projects that have some chance of being realized during my lifetime without woolgathering about imaginary thirty-seven-million-year journeys. Smeth was perfectly right about it.”
“Of course! I’m always right,” a voice said loudly at his ear. Bram turned and saw Smeth standing there with a fatuous smile on his face. “What is it I’m right about?”
“The impossible mass ratios for traveling near the speed of light.”
“Oh, that.” Smeth waved a negligent hand. “Forget about it. We’re not going to have to carry our fuel anymore.”
“He’s going to tell you all about using interstellar hydrogen, depend on it,” Jao said, crowding in behind Smeth with a drink cradled in one fist. “Hi, Mim.”
Trist followed, raising his eyes heavenward for Bram’s benefit.
Smeth scowled. “That’s what the probe project is all about. The Nar want to build a probe that can reach the galactic center in a reasonable length of time. On the order of fifty thousand years. And it’s beginning to look more and more possible. And yes, we think we can do it by scooping up hydrogen atoms in space and squeezing the plasma to induce fusion.”
“Don’t fail to tell him about exhaust velocities,” Jao prompted, winking at Bram.
“Go ahead, have your fun,” Smeth said.
Trist sighed. “The original idea,” he said, “was to collect interstellar hydrogen and use it both for reaction mass and for an energy source. But matter is matter, even when you strip it down, and even though you can expel it at velocities brushing the speed of light, all our studies indicated that there was a practical limiting factor of about ninety-eight percent.” He turned to Jao. “That about right?”
“Yah. Ninety-eight percent. For plasma
and all that junk.”
“The ultimate exhaust velocity, by definition, would be provided by a pure photon drive. But that would require the total conversion of matter into energy, and we don’t know how to do that. So photon drives of the various sorts we’d been kicking around — mostly they boiled down to turning a fraction of the energy of matter into laser light — are inefficient.”
“Yah, weak,” Jao said.
“Now we come to the hadronic photon. Under certain circumstances, it’s possible to increase the energy of a photon by a factor of from one to ten billion. And when you do, it takes on the properties of a hadron. It acts as though it has mass, like a proton, for instance. It has energy and momentum that are conserved.”
“First you have to pump all that energy into it,” Bram pointed out. “Ten billion times, did you say?”
“Hey, not bad for a biologist,” Jao said. “Yah, all that has to come out of the ramjet fusion reaction in the first place.”
“The point is,” Trist said, “that we don’t have to annihilate matter to get our beam of superphotons. It’s done strictly through electromagnetic interactions that we know how to handle. In theory, at least.”
“What you do is you swat pulsed laser photons with a high-energy electron beam and scatter them a hundred eighty degrees,” Jao said. “They pick up the energy of the swat.”
Trist nodded. “Then you focus the back-scattered photons — hadronic photons now — in the electromagnetic throat of the drive, and since they have a temporary nonzero mass, your vehicle not only gets a healthy kick, but gets it at the speed of light.”
“Don’t forget to mention the four-wave conjugate mirrors,” Jao said, pulling at his sleeve.
“Oh, those. Yes. That’s how we collect all those muscular photons that’re scattering in all directions and herd them into a tight beam.”
“It all sounds wonderful,” Bram said. “I think.”
“Of course, these aren’t real photons we’re talking about,” Trist said.
“What?”
“They’re virtual photons. They exist by courtesy of the uncertainty principle.”
“Now you’ve lost me,” Bram said. “Mim, do you have any idea what he’s talking about?”
“Not a clue,” she said, looking amused.
“All physicists are crazy,” Jao said. “It’s a well-known fact.”
Smeth gave a snort. “You two are crazy. I’ll grant that much.”
“Jao’s right,” Trist said. “We’re all crazy, Smeth included. We believe in things that don’t exist. The hadronic photon has no right to be. It’s supposed to hold hands with another photon, so that momentum and energy can be balanced. But it doesn’t. It lives its brief solitary life, violating all the superstitions of quantum electrodynamics. The universe finds this a very unsatisfactory state of affairs. So our imaginary friend disappears before it can be detected. It materializes into a rho vector meson, which immediately decays into two pions, and those can be detected.”
“But we don’t care by then,” Jao said with a red-bearded grin. “Let the universe sort things out. By that time our mythical photon’s given its mythical kick to the vehicle.”
“What’s this about the uncertainty principle?” Bram said.
“That’s the beauty of it. The shorter the time the virtual photon exists, the larger the uncertainty about its mass. Theoretically, it can assume a whole range of masses. There’s only one problem.”
“What’s that?”
“The Nar find it hard to believe in imaginary photons. They can’t seem to bend their minds around the concept. So they’re leaving it to us for the time being. Or rather to these fellows. I’m out of it. I’ll be on Juxt One, soaking up the Juxtshine and getting a tan.”
“The Nar will come around to it eventually,” Trist said. “Through the back door. They have their own way of looking at abstractions. In the meantime, they’re giving us the benefit of the doubt. They know that humans have a peculiar talent for physics.”
“Very peculiar,” Bram agreed.
“I don’t know,” Mim said. The three physicists looked at her in surprise. “It’s easy for a musician to believe in things that only exist by virtue of other things that they turn into, but that are real nonetheless.”
“How so, Mim?” Trist asked.
“It happens all the time in music. Like some of the Chopin pieces. Cascades of unresolved chords that collapse into other unresolved chords linked by carry-over notes and never come to a resting place. If you play them individually, they’re all ugly discords. But they imply harmonies that the ear fills in. Harmonies that are just as real as if they existed as actual sound. In fact, you can diagram them if you care to, as a student exercise.” She wrinkled her nose. “Olan was always having to restrain students who thought they were ‘correcting’ the discords.”
“I like that,” Jao said. “A universe that plays it by ear. That hints rather than states. Matter and energy don’t actually exist. They’re only implied by the transition states.”
“We’ll make a physicist out of you yet, Mim,” Trist said. “You’ve got the divine madness.”
Mim laughed. “I find it complicated enough sometimes just to try to beat time.”
“Beat time,” Jao said. “That’s what we’re trying to do.”
“Why do the Nar want to reach the galactic center in fifty thousand years?” Bram asked.
Trist looked him in the eye. “Don’t you know? You work at the biocenter.”
“Just my own little septum of it.”
Trist and Jao exchanged glances. “Are you familiar with the absent tidings paradox?”
Bram laughed. “What’s that?”
“If intelligent life arises, and if billions of years have elapsed since the universe became hospitable enough to give rise to it, where are they all?”
“But that’s been disproved. We know it happened at least twice.”
“Make that three times,” Trist said.
Bram glanced up sharply. “What are you talking about?”
“The big ear that discovered Original Man finally hit the jackpot again. A couple of centuries ago, the Nar gave up on the nearby galaxies and turned the search inward, toward the galactic center. Worse odds, but closer to home, so to speak. They worked out computer techniques for filtering all the isotropic noise, and they used variable search strategies — the hydrogen line, the hydroxyl line, pulsed transmissions at all frequencies simultaneously, and so forth. All very discouraging. Finally, about the time redbeard here began to develop fuzz, they started searching at low frequencies along the magnetic field lines in the galaxy. The theory was that the lines would act as a guide, beating the inverse square rule, and that you might pick up very weak signals at very great distances.”
“How great?” Bram said.
“They don’t know. Maybe thirty or forty thousand light-years in toward the core.”
“What’s in the signals?”
“Pure noise. No information content at all. Scraps of carrier waves, maybe. Leaking radar. But there’s no doubt that they’re of artificial origin.”
“I’d have thought the news would be all over the place.”
“You know the Nar. They don’t go crazy like us. They only started picking up the signals a couple of years ago, and then they weren’t sure what they were. It took a while for the implications to sink in, and then the group leaders on the probe project started mulling it over with some of their opposite numbers at the biocenter, and it started to spread to some of the policy touch groups, and it’s trickling down. Some of us know, and one or two people on the human advisory council have been told, and I suppose some hacker on news net will pick it up, and then everybody will know.”
“So that’s why the Nar want to reach the galactic center,” Bram said. “No —” He remembered that the project had started long before the Nar had picked up the signals that were the evidence of life. Smeth had told him about it years ago, saying that it had someth
ing to do with some grand racial purpose of the Nar. “— you’ve all been working on the project all along.”
Trist nodded. “But now it isn’t a blind gamble — a leap into the dark. The project’s going to have a lot more impetus now.”
Smeth’s shaggy head bobbed up and down. “That’s what I’ve been trying to tell you, Jao, old son. You picked the wrong time to leave the project. We’re going to get more funding, more recognition. And you’ll be stirring up vats of yeast on Juxt One.”
Jao ignored him. “You see, Bram, Mim, — the probe couldn’t reach the vicinity of those radio signals for another thirty or forty thousand years even if it started out in the next century. And then it could miss them by tens or hundreds of light-years. We don’t know exacly where they are. So there’s not much point in sending back telemetry that wouldn’t get here for sixty or eighty thousand years. Or trying to have a dialog with them at that exchange rate.”
“They might not even be there anymore,” Trist added. “Maybe their civilization destroyed itself long ago. That kind of radio leakage is the signature of an early stage of a radio age. Temporary. We don’t — the Nar, I mean — put out that much stray radio energy anymore. Or maybe they’re getting more advanced. A few more centuries of listening on their wavelength will tell us more — long before the probe could let us know anything.”
Jao’s face was flushed. “Or maybe they’ve been spreading toward us for the last thirty or forty thousand years — just behind the speed of light — and they’re about to burst into our volume of space, somewhere out there beyond Juxt One, any day now!”
Bram was caught up in the vision. He could see that Mim was, too. “Or maybe,” he said, “they’re spreading at the same slow rate as the Nar, in their version of a sailship at fourteen percent of the speed of light, or on a boron fusion-fission drive at twenty percent, and some tens of thousands of years from now the two expanding spheres will intersect.”
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