He paused outside the handsomely-panelled door of his private cabin, one hand on the thumb-plate that controlled entrance. His lips were set in a tight thin line. "And remember this, Alan," he said. "Steve's not your twin brother any more. You're only seventeen, and he's almost twenty-six. He'll never be your twin again."
With sudden warmth the captain squeezed his son's arm. "Well, better get up there to eat, Alan. This is going to be a busy day for all of us."
He turned and went into the cabin.
Alan moved along the wide corridor of the great ship toward the mess hall in Section C, thinking about his brother. It had been only about six weeks before, when the Valhalla had made its last previous stop on Earth, that Steve had decided to jump ship.
The Valhalla's schedule had called for them to spend two days on Earth and then leave for Alpha Centauri with a load of colonists for Alpha C IV. A starship's time is always scheduled far in advance, with bookings planned sometimes for decades Earthtime by the Galactic Trade Commission.
When blastoff time came for the Valhalla, Steve had not reported back from the Starmen's Enclave where all Spacers lived during in-port stays.
Alan's memories of the scene were still sharp. Captain Donnell had been conducting check-off, making sure all members of the Crew had reported back and were aboard. This was a vital procedure; in case anyone were accidentally left behind, it would mean permanent separation from his friends and family.
He had reached the name Donnell, Steve. No answer came. Captain Donnell called his name a second time, then a third. A tense silence prevailed in the Common Room of the starship, where the Crew was assembled.
Finally Alan made himself break the angry silence. "He's not here, Dad. And he's not coming back," he said in a hesitant voice. And then he had had to explain to his father the whole story of his unruly, aggressive twin brother's plan to jump ship--and how Steve had tried to persuade him to leave the Valhalla too.
Steve had been weary of the endless shuttling from star to star, of forever ferrying colonists from one place to another without ever standing on the solid ground of a planet yourself for more than a few days here, a week there.
Alan had felt tired of it too--they all did, at some time or another--but he did not share his twin's rebellious nature, and he had not gone over the hill with Steve.
Alan remembered his father's hard, grim expression as he had been told the story. Captain Donnell's reaction had been curt, immediate, and thoroughly typical: he had nodded, closed the roll book, and turned to Art Kandin, the Valhalla's First Officer and the Captain's second-in-command.
"Remove Crewman Donnell from the roster," he had snapped. "All other hands are on board. Prepare for blastoff."
Within the hour the flaming jets of the Valhalla's planetary drive had lifted the great ship from Earth. They had left immediately for Alpha Centauri, four and a half light-years away. The round trip had taken the Valhalla just six weeks.
During those six weeks, better than nine years had passed on Earth.
Alan Donnell was seventeen years old.
His twin brother Steve was now twenty-six.
"Happy rising, Alan," called a high, sharp voice as he headed past the blue-painted handholds of Gravity Deck 12 on his way toward the mess hall.
Startled, he glanced up, and then snorted in disgust as he saw who had hailed him. It was Judy Collier, a thin, stringy-haired girl of about fourteen whose family had joined the Crew some five ship-years back. The Colliers were still virtual newcomers to the tight group on the ship--the family units tended to remain solid and self-contained--but they had managed to fit in pretty well by now.
"Going to eat?" she asked.
"Right enough," said Alan, continuing to walk down the plastifoam-lined corridor. She tagged along a step or two behind him.
"Today's your birthday, isn't it?"
"Right enough," Alan said again, more abruptly. He felt a sudden twinge of annoyance; Judy had somehow developed a silly crush on him during the last voyage to Alpha C, and since then she had contrived to follow him around wherever he went, bombarding him with questions. She was a silly adolescent girl, Alan thought scornfully.
"Happy birthday," she said, giggling. "Can I kiss you?"
"No," returned Alan flatly. "You better watch out or I'm going to get Rat after you."
"Oh, I'm not afraid of that little beast," she retorted. "One of these days I'll chuck him down the disposal hatch like the little vermin he--ouch!"
"You watch out who you're calling vermin," said a thin, dry, barely-audible voice from the floor.
Alan glanced down and saw Rat, his pet and companion, squatting near Judy and flicking his beady little red eyes mischievously in the direction of the girl's bare skinny ankle.
"He bit me," Judy complained, gesturing as if she were going to step on the little creature. But Rat nimbly skittered to one side, leaped to the trousers of Alan's uniform, and from there clambered to his usual perch aboard his master's shoulder.
Judy gestured at him in frustration, stamped her foot, and dashed away into the mess hall. Chuckling, Alan followed and found his seat at the bench assigned to Crewmen of his status quotient.
"Thanks, fellow," he said softly to the little being on his shoulder. "That's kid's getting to be pretty annoying."
"I figured as much," Rat said in his chittering birdlike voice. "And I don't like the way she's been looking at me. She's just the kind of individual who would dump me in a disposal hatch."
"Don't worry about it," Alan said. "If she pulls anything of the sort I'll personally see to it that she goes out right after you."
"That does me a lot of good," Rat said glumly as Alan's breakfast came rolling toward him on the plastic conveyor belt from the kitchen.
Alan laughed and reached avidly for the steaming tray of food. He poured a little of his synthorange juice into a tiny pan for Rat, and fell to.
Rat was a native of Bellatrix VII, an Earth-size windswept world that orbited the bright star in the Orion constellation. He was a member of one of the three intelligent races that shared the planet with a small colony of Earthmen.
The Valhalla had made the long trip to Bellatrix, 215 light-years from Earth, shortly before Alan's birth. Captain Donnell had won the friendship of the little creature and had brought him back to the ship when time came for the Valhalla to return to Earth for its next assignment.
Rat had been the Captain's pet, and he had given Alan the small animal on his tenth birthday. Rat had never gotten along well with Steve, and more than once he had been the cause of jealous conflicts between Alan and his twin.
Rat was well named; he looked like nothing so much as a small bluish-purple rodent, with wise, beady little eyes and a scaly curling tail. But he spoke Terran clearly and well, and in every respect he was an intelligent, loyal, and likable creature.
They ate in silence. Alan was halfway through his bowl of protein mix when Art Kandin dropped down onto his bench facing him. The Valhalla's First Officer was a big pudgy-faced man who had the difficult job of translating the concise, sometimes almost cryptic commands of Alan's father into the actions that kept the great starship going.
"Good rising, Alan. And happy birthday."
"Thanks, Art. But how come you're loafing now? Seems to me you'd be busy as a Martian dustdigger today, of all days. Who's setting up the landing orbit, if you're here?"
"Oh, that's all been done," Kandin said lightly. "Your Dad and I were up all last night working out the whole landing procedure." He reached out and took Rat from Alan's shoulder, and began to tickle him with his forefinger. Rat responded with a playful nip of his sharp little teeth. "I'm taking the morning off," Kandin continued. "You can't imagine how nice it's going to be to sit around doing nothing while everyone else is working, for a change."
"What's the landing hour?"
"Precisely 1753 tonight. It's all been worked out. We actually are in the landing orbit now, though the ship's gimbals keep you from feeling it. We'll touch down tonight and move into the Enclave tomorrow." Kandin eyed Alan with sudden suspicion. "You're planning to stay in the Enclave, aren't you?"
Alan put down his fork with a sharp tinny clang and stared levelly at the First Officer. "That's a direct crack. You're referring to my brother, aren't you?"
"Who wouldn't be?" Kandin asked quietly. "The captain's son jumping ship? You don't know how your father suffered when Steve went over the hill. He kept it all hidden and just didn't say a thing, but I know it hit him hard. The whole affair was a direct reflection on his authority as a parent, of course, and that's why he was so upset. He's a man who isn't used to being crossed."
"I know. He's been on top here so long, with everyone following his orders, that he can't understand how someone could disobey and jump ship--especially his own son."
"I hope you don't have any ideas of----"
Alan clipped off Kandin's sentence before it had gotten fully started. "I don't need advice, Art. I know what's right and wrong. Tell me the truth--did Dad send you to sound me out?"
Kandin flushed and looked down. "I'm sorry, Alan. I didn't mean--well----"
They fell silent. Alan returned his attention to his breakfast, while Kandin stared moodily off into the distance.
"You know," the First Officer said finally, "I've been thinking about Steve. It just struck me that you can't call him your twin any more. That's one of the strangest quirks of star travel that's been recorded yet."
"I thought of that. He's twenty-six, I'm seventeen, and yet we used to be twins. But the Fitzgerald Contraction does funny things."
"That's for sure," Kandin said. "Well, time for me to start relaxing." He clapped Alan on the back, disentangled his long legs from the bench, and was gone.
The Fitzgerald Contraction does funny things, Alan repeated to himself, as he methodically chewed his way through the rest of his meal and got on line to bring the dishes to the yawning hopper that would carry them down to the molecular cleansers. Real funny things.
He tried to picture what Steve looked like now, nine years older. He couldn't.
As velocity approaches that of light, time approaches zero.
That was the key to the universe. Time approaches zero. The crew of a spaceship travelling from Earth to Alpha Centauri at a speed close to that of light would hardly notice the passage of time on the journey.
It was, of course, impossible ever actually to reach the speed of light. But the great starships could come close. And the closer they came, the greater the contraction of time aboard ship.
It was all a matter of relativity. Time is relative to the observer.
Thus travel between the stars was possible. Without the Fitzgerald Contraction, the crew of a spaceship would age five years en route to Alpha C, eight to Sirius, ten to Procyon. More than two centuries would elapse in passage to a far-off star like Bellatrix.
Thanks to the contraction effect, Alpha C was three weeks away, Sirius a month and a half. Even Bellatrix was just a few years' journey distant. Of course, when the crew returned to Earth they found things completely changed; years had passed on Earth, and life had moved on.
Now the Valhalla was back on Earth again for a short stay. On Earth, starmen congregated at the Enclaves, the cities-within-cities that grew up at each spaceport. There, starmen mingled in a society of their own, without attempting to enter the confusing world outside.
Sometimes a Spacer broke away. His ship left him behind, and he became an Earther. Steve Donnell had done that.
The Fitzgerald Contraction does funny things. Alan thought of the brother he had last seen just a few weeks ago, young, smiling, his own identical twin--and wondered what the nine extra years had done to him.
Alan dumped his breakfast dishes into the hopper and walked briskly out of the mess hall. His destination was the Central Control Room, that long and broad chamber that was the nerve-center of the ship's activities just as the Common Recreation Room was the center of off-duty socializing for the Crew.
He found the big board where the assignments for the day were chalked, and searched down the long lists for his own name.
"You're working with me today, Alan," a quiet voice said.
He turned at the sound of the voice and saw the short, wiry figure of Dan Kelleher, the cargo chief. He frowned. "I guess we'll be crating from now till tonight without a stop," he said unhappily.
Kelleher shook his head. "Wrong. There's really not very much work. But it's going to be cold going. All those chunks of dinosaur meat in the preserving hold are going to get packed up. It won't be fun."
He scanned the board, looking down the rows for the list of cargo crew. Sure enough, there was his name: Donnell, Alan, chalked in under the big double C. As an Unspecialized Crewman he was shifted from post to post, filling in wherever he was needed.
"I figure it'll take four hours to get the whole batch crated," Kelleher said. "You can take some time off now, if you want to. You'll be working to make up for it soon enough."
"I won't debate the point. Suppose I report to you at 0900?"
"In case you need me before then, I'll be in my cabin. Just ring me."
Once back in his cabin, a square cubicle in the beehive of single men's rooms in the big ship's fore section, Alan unslung his pack and took out the dog-eared book he knew so well. He riffled through its pages. The Cavour Theory, it said in worn gold letters on the spine. He had read the volume end-to-end at least a hundred times.
"I still can't see why you're so wild on Cavour," Rat grumbled, looking up from his doll-sized sleeping-cradle in the corner of Alan's cabin. "If you ever do manage to solve Cavour's equations you're just going to put yourself and your family right out of business. Hand me my nibbling-stick, like a good fellow."
Alan gave Rat the much-gnawed stick of Jovian oak which the Bellatrician used to keep his tiny teeth sharp.
"You don't understand," Alan said. "If we can solve Cavour's work and develop the hyperdrive, we won't be handicapped by the Fitzgerald Contraction. What difference does it make in the long run if the Valhalla becomes obsolete? We can always convert it to the new drive. The way I see it, if we could only work out the secret of Cavour's hyperspace drive, we'd----"
"I've heard it all before," Rat said, with a note of boredom in his reedy voice. "Why, with hyperspace drive you'd be able to flit all over the galaxy without suffering the time-lag you experience with regular drive. And then you'd accomplish your pet dream of going everywhere and seeing everything. Ah! Look at the eyes light up! Look at the radiant expression! You get starry-eyed every time you start talking about the hyperdrive!"
Alan opened the book to a dog-eared page. "I know it can be done eventually. I'm sure of it. I'm even sure Cavour himself actually succeeded in building a hyperspace vessel."
"Sure," Rat said drily, switching his long tail from side to side. "Sure he built one. That explains his strange disappearance. Went out like a snuffed candle, soon as he turned on his drive. Okay, go ahead and build one--if you can. But don't bother booking passage for me."
"You mean you'd stay behind if I built a hyperspace ship?"
"Sure I would." There was no hesitation in Rat's voice. "I like this particular space-time continuum very much. I don't care at all to wind up seventeen dimensions north of here with no way back."
"You're just an old stick-in-the mud." Alan glanced at his wristchron. It read 0852. "Time for me to get to work. Kelleher and I are packing frozen dinosaur today. Want to come along?"
Rat wiggled the tip of his nose in a negative gesture. "Thanks all the same, but the idea doesn't appeal. It's nice and warm here. Run along, boy; I'm sleepy." He curled up in his cradle, wrapped his tail firmly around his body, and closed his eyes.
There was a line waiting at the entrance to the freezer section, and Alan took his place on it. One by one they climbed into the spacesuits which the boy in charge provided, and entered the airlock.
For transporting perishable goods--such as the dinosaur meat brought back from the colony on Alpha C IV to satisfy the heavy demand for that odd-tasting delicacy on Earth--the Valhalla used the most efficient freezing system of all: a compartment which opened out into the vacuum of space. The meat was packed in huge open receptacles which were flooded just before blastoff; before the meat had any chance to spoil, the lock was opened, the air fled into space and the compartment's heat radiated outward. The water froze solid, preserving the meat. It was just as efficient as building elaborate refrigeration coils, and a good deal simpler.
The job now was to hew the frozen meat out of the receptacles and get it packed in manageable crates for shipping. The job was a difficult one. It called for more muscle than brain.
As soon as all members of the cargo crew were in the airlock, Kelleher swung the hatch closed and threw the lever that opened the other door into the freezer section. Photonic relays clicked; the metal door swung lightly out and they headed through it after Kelleher gave the go-ahead.
Alan and the others set grimly about their work, chopping away at the ice. They fell to vigorously. After a while, they started to get somewhere. Alan grappled with a huge leg of meat while two fellow starmen helped him ease it into a crate. Their hammers pounded down as they nailed the crate together, but not a sound could be heard in the airless vault.
After what seemed to be three or four centuries to Alan, but which was actually only two hours, the job was done. Somehow Alan got himself to the recreation room; he sank down gratefully on a webfoam pneumochair.