by Larry Niven
I fear the unknown beasts of the past. I cannot breathe the air.
I cannot recognize the edible plants. I would not kill animals for food. I don't know which would kill me.
The Earth's past is as foreign to me as another planet.
The Palace Veterinarian was busy hooking the ostrich intravenously to tubing of several colors. Svetz's pocket phone rang.
For a wild moment Svetz considered not answering. But good manners won out, and Svetz opened the phone.
"There's trouble," said Ra Chen's image. "Zeera's cage is on its way back. She must have pulled the go-home lever right after she called for the big extension cage."
"She left before the big cage could get there?"
"Yah," said Ra Chen. "Whatever happened must have happened fast. If she called for the big cage, then she had the automobile. A moment later she aborted the mission. Svetz, I'm worried."
"I'd hate to leave now, sir." Svetz turned to look at the ostrich. In that moment all of the bird's feathers fell out, leaving it plump and naked.
That decided him. "I can't leave now, sir. We'll have a full-grown roc in a few minutes."
"What? Good! But how?"
"The ostrich was a neotenous offshoot of the roc. We've produced a throwback."
"Good! Stick with it, Svetz. We'll handle it here." Ra Chen switched off.
The Palace Veterinarian said, "You shouldn't make promises you can't keep."
Svetz's heart leapt. "Trouble?"
"No. It's going beautifully so far."
"All the feathers fell out. Is that good?"
"Don't worry about it. See for yourself: already there's a coat of down. Your ostrich is reverting to chickhood," she said cheerfully. "Its ancestor's chickhood. If the ancestor really was no bigger than a turkey before it lost the ability to fly, it'll be even smaller as a chick."
"What'll happen then?"
"It'll drown in its own fat."
"We should have taken a clone."
"Too late. Look at it now, look at the legs. They aren't nearly as overdeveloped."
The bird was a big ball of pale yellow down. Its frame had shrunk, but its legs had shrunk much more. Standing, it would have been no more than four feet tall. The extra mass had turned to fat, so that the ostrich was nearly spherical; it bulged like a poolside toy, lying on its inflated side in a pool of feathers.
"Now it really looks like a chick," said Svetz.
"It does, Svetz. In fact, it is. That was a big chick. The adult is going to be tremendous." The Palace Veterinarian jumped to her feet. "Svetz, we've got to hurry. Is there a basic yeast source in this cage?"
"Sure. Why?"
"He'll starve at the rate he's growing, unless. . . just show me, Svetz."
The animals of the Zoo ate yeast, like everyone else, but with special additives for each animal. A brain tap could induce the animal to imagine it was eating whatever it was used to eating when the time probe had picked it up.
Svetz showed her the yeast tap. She hooked the pipeline to one of the machines on her floating platform; she made adaptations, added another machine.
The bird grew visibly. Its fat layer shrank, deflated. Its legs and wings stretched outward. The beak began to take a distinctive hooked form, sharp and wicked looking.
Svetz began to feel panic. Beneath its downy feathers the bird was little more than taut skin stretched over long bones.
The yeast was now feeding directly into two tanks on the floating platform, and from there into the colored tubes. Somehow the Palace Veterinarian was converting the yeast directly into sugar-plasma.
"It's working now," she said. "I wasn't sure it would. He'll be all right now, if the growth cycle slows down in time." She smiled up at him. "You were right all along. The ostrich was a neotenous roc."
At that moment the light changed.
Svetz wasn't sure what had disturbed him. But he looked up- and the sky was baby blue from the horizon to the zenith.
"What is it?" The woman beside him was bemused rather than frightened. "I never saw a color like that in my life!"
"I have."
"What is it?"
"Don't worry about it. But keep your filter helmet on, especially if you have to leave the cage. Can you remember that?"
"Of course." Her eyes narrowed. "You know something about this, Svetz. It's something to do with time, isn't it?"
"I think so." Svetz used the key beam then, to avoid further questions. The glass peeled back to let him out.
He turned for a last look through the glass.
The Palace Veterinarian looked frightened. She must have guessed too much for her own comfort. But she turned away to care for her patient.
The ostrich lay on its side, its eyes open now. It was tremendous, and still scrawny despite the volume of the intravenous feed. Its feathers were changing color. The bird would be black and green.
It was half as big as the elephant next door . . . whose air of gray wisdom was giving way to uneasiness as he watched.
It looked nothing like an ostrich.
The sky was baby blue, the blue of the deep past, crossed with fluffy clouds of clean and shining white. Blue from the horizon to the zenith, without a trace of the additives that ought to be there.
Unconscious men and women lay everywhere. Svetz dared not stop to help. What he had to do was more important.
He slowed to a walk as he neared the Center. There was pain like a knife blade inserted between his partly healed ribs.
ITR crewmen had fallen in the walkway around the Center, presumably after staggering outside. And there was the Secretary-General's automobile sitting quietly in front. Behind it, flat on his back, was Ra Chen.
What did he think he was doing there?
Svetz heard the purr of the motor as he approached. So that was it Ra Chen must have hoped that the exhaust would revive him. Damn clever; and it should have worked. Why hadn't it?
Svetz looked into the polished metal guts of the motor as he passed. The motor had changed...somehow. What ran it now? Steam? Electricity? A flywheel? In any event, the exhaust pipe Ra Chen had been searching for was no longer there.
Ra Chen was alive, his pulse rapid and frantic. But he wasn't breathing. Or. . . yes, he was. He was breathing perhaps twice a minute as carbon dioxide built up enough to activate the reflex.
Svetz went on into the Center.
More than a dozen men and women had collapsed across lighted control panels. Three more figures sprawled in an aisle. The Secretary-General lay in angular disorder, smiling foolishly up at the ceiling. His guards wore troubled sleeping expressions and held drawn guns.
The small extension cage had not returned.
Svetz looked into the empty gap in the time machine, and felt terror. What could he accomplish without Zeera to tell him what had gone wrong?
From 50 AnteAtomic to the present was a thirty minute trip. Ra Chen's call to the Zoo must have come less than thirty minutes ago. Weird, how an emergency could telescope time.
Unless that was a side effect of the paradox. Unless the paradox had chopped away Zeera's extension cage and left her stranded in the past, or cast off into an alternate world line, or...
There bad never been a temporal paradox.
Math was no help. The mathematics of time travel was riddled with singularities.
Last year somebody had tried to do a topological analysis of the path of an extension cage. He had proved not only that time travel was impossible, but that you couldn't travel faster than light either. Ra Chen had leaked the news to Space on the off chance that their hyperdrive ships would stop working.
What to do? Start putting filter helmets on everyone? Great, but the helmets weren't kept at the Center; he'd have to go across town. Did he dare leave the Center?
Svetz forced himself to sit down.
Minutes later, he snapped alert at the pop of displaced air. The small extension cage had returned. Zeera was crawling out of the circular doorway.
"G
et back in there," Svetz ordered. "Quick!"
"I don't take orders from you, Svetz." She brushed past him and looked about her. "The automobile's gone. Where's Ra Chen?" Zeera's face was blank with shock and exhaustion. Her voice was a monotone, ragged at the edges.
Svetz took her arm. "Zeera, we've-"
She jerked away. "We've got to do something. The automobile's gone. Didn't you hear me?"
"Did you hear me? Get back in the extension cage!"
"But we've got to decide what to do. Why can't I smell anything?" She sniffed at air that was scentless, empty, dead. She looked about herself in bewilderment, realizing for the first time just how strange everything was.
Then the eyes rolled up in her head, and Svetz stepped forward to catch her.
He studied her sleeping face across the diameter of the extension cage. It was very different from her waking face. Softer, more vulnerable. And prettier. Zeera had quite a pretty face.
"You should relax more often," he said.
His ribs throbbed where the ostrich had kicked him. The pain seemed to beat like a heart.
Zeera opened her eyes. She asked, "Why are we in here?"
"The extension cage has its own air system," said Svetz. "You can't breathe the outside air."
"Why not?"
"You tell me."
Her eyes went wide. "The automobile! It's gone!"
"Why?"
"I don't know. Svetz, I swear I did everything right. But when I turned on the duplicator the automobile disappeared!"
"That . . . doesn't sound at all good." Svetz strove to keep his voice level. "What did you-"
"I did it just the way they taught me! I hooked the glow-painted end to the frame, set the dials for an estimated mass plus a margin of error, read the dials off-"
"You must have hooked up the wrong end somehow. Wait a minute. Were you using the infrared flash?"
"Of course. It was dead of night"
"And you'd taken the pills so you'd be able to see infrared."
"Do you always think that slowly, Svetz?" Then her eyes changed, and Svetz knew she'd seen it. "I was seeing infrared. Of course. I hooked up the hot end."
"The duplicator end. Sure. That would duplicate empty space where there was an automobile. You'd get emptiness at both ends."
Zeera relaxed against the curved side of the extension cage, with her arms hooked under her knees. Presently she said, "Henry Ford sold that automobile for two hundred dollars, according to the book Later he had trouble getting financed. Could the money have been crucial?"
"It must have been. How much is two hundred dollars?"
"Then someone else used mass production to make automobiles. And he must have liked steam or electricity."
"Steam, I'd guess. Steam came first."
"Tell me this, Svetz. If the air changed, why didn't we change with it? We evolved to be able to breathe air with a certain percentage of carbon monoxide and sulphur dioxide and nitrous and nitric oxides and so forth. Shouldn't the evolution have been canceled too? For that matter, why do we remember?"
"There's a lot we don't know about time travel. How do you expect logic to hold when paradoxes hold too?"
"Does that mean you don't know?"
"Yes."
"I'm not nagging, Svetz. I don't know either."
More silence.
"It's clear enough," Zeera said presently. "You have to go back and warn myself to get the duplicator on straight."
"That won't work. It didn't work. If you'd gotten the ends of the duplicator straight, we wouldn't be in this mess. Therefore you didn't."
She looked irritated. "Too logical. Well, what then?"
"Maybe we can go around you." Svetz hesitated, then plunged in. "Try this. Send me back to an hour before the earlier Zeera arrives. The automobile won't have disappeared yet. I'll duplicate it, duplicate the duplicate, take the reversed duplicate and the original automobile past you in the big extension cage. That lets you destroy the duplicate. I reappear after you're gone, leave the original automobile, and come back here with the reversed duplicate. How's that?"
"It sounded great. Would you mind going through it again?"
"Let's see. I go back to-"
She was laughing at him. "Never mind. But it has to be me, Svetz. You couldn't find your way. You couldn't ask directions or read the street signs. You'll have to stay here and man the machinery."
Reluctantly Svetz agreed.
They were leaving the extension cage when there came a scream like the end of the world.
Momentarily they froze. Then Svetz ran around the swelling flank of the cage. Zeera followed, wearing the filter helmet she had worn during her attempt to duplicate Ford's automobile.
One wall of the Center was glass. It framed a crest of hill across from the palace and a double row of cages that made up the Zoo. One of the cages was breaking apart as they watched, smashing itself to pieces like-
-like an egg hatching. And like a chick emerging, the roe stood up in the ruin of its cage.
The scream came again.
"What is it?" Zeera whispered.
"It was an ostrich. I'd hate to give it a name now."
The bird seemed to move in slow motion. There was so much of it! Green and black, beautiful and evil, big as eternity, and a crest of golden feathers had sprouted on its forehead. Its hooked beak descended toward a cage.
That cage ripped like paper.
Zeera was shaking his arm. "Come on! If it came from the Zoo, we don't need to worry about it. It'll suffocate when we get the car back where it belongs."
"Oh. Bight," said Svetz. They went to work moving the big extension cage a few hours further back in time.
When Svetz looked again, the bird was just taking to the air. Its wings flapped like sails, and their black shadows swept like cloud shadows over the houses. As the roe rose fully into view, Svetz saw that something writhed and struggled in its tremendous talons.
Svetz recognized it. . . and realized just how big the roe really was.
"It's got ELEPHANT," he said. An inexplicable sorrow gripped his heart; inexplicable, for Svetz hated animals.
"What? Come on, Svetz!"
"Um? Oh, yes." He helped Zeera into the small extension cage and sent it on its way.
Despite its sleeping crew, the machinery of the Center seemed to be working perfectly. If anything got off, Svetz would have six men's work to do. Therefore he prowled among the control boards, alert for any discrepancy, making minor adjustments
And occasionally he looked out the picture window.
The roc reached a tremendous height. Any ordinary bird would have been invisible long since. But the roc was all too visible, hovering in the blue sky while it killed and ate ELEPHANT.
Time passed.
Twenty minutes for Zeera to get back.
More time to make two duplicates of the automobile. Load them into the big extension cage. Then to signal Svetz- The signal came. She had the cars; she wanted to be moved forward. Svetz played it safe and moved her forward six hours almost to dawn. She might be caught by an early riser, but at least Ford would have his automobile.
The roc had finished its bloody meal. ELEPHANT was gone, bones and all. And-Svetz watched until he was sure-the bird was dropping, riding down the sky on outstretched wings.
Svetz watched it grow bigger, and bigger yet, until it seemed to enfold the universe. It settled over the Center like a tornado cloud, in darkness and wind. Like twin tornado tunnels, two sets of curved talons touched down in the walkway.
The bird bent low. An inhuman face looked in at Svetz through the picture window. It nearly filled the window.
It knows me, Svetz thought. Even a bird's brain must be intelligent in a head that size.
The vast head rose ponderously out of sight above the roof.
I had the ostrich. I should have been satisfied, thought Svetz. A coin in the hand is worth two in the street. The ancient proverb could as easily be applied to birds.
&
nbsp; The roof exploded downward around a hooked beak. Particles of concrete spattered against the walls and floor. A yellow eye rolled and found Svetz, but the beak couldn't reach him. Not through that hole.
The head withdrew through the roof.
Three red lights. Svetz leapt for the board and began twisting dials. He made two lights turn green, then the third. It had not occurred to him to run. The bird would find him wherever he hid.
There! Zeera had pulled the go-home lever. From here it was all automatic.
Crash!
Svetz was backed up against the big time machine, pinned by a yellow eye as big as himself. Half the roof was gone, but still the bird's beak couldn't reach him. But a great talon came seeking him through the shattered glass.
The light changed.
Svetz sagged. Behind the green and black feathers he could see that the sky had turned pale yellow-green, marked with yellow-brown streamers of cloud.
The bird sniffed incredulously. It didn't have to be told twice. Its head rose through the ceiling; it stepped back from the Center for clearance; its great wings came down like thunderclouds.
Svetz stepped out to watch it rise.
He had to hug an ornamental pillar. The wind of its wings was a hurricane. The bird looked down once, and recognized him, and looped away.
It was still well in view, rising and circling, when Zeera stepped out to join him. Presently Ra Chen was there to follow their eyes. Then half the Center maintenance team was gaping upward in awe and astonishment . . . while the bird dwindled to a black shadow. Black against pale green, climbing, climbing.
One sniff had been enough. The bird's brain was as enormously proportioned as the rest of it. It had started climbing immediately, without waiting to snatch up its dessert.
Climbing, climbing toward the edge of space. Reaching for clean air.
The Secretary-General stood beside Svetz, smiling in wonder, chuckling happily as he gazed upward.
Was the roe still climbing? No, the black shadow was growing larger, sliding down the sky. And the slow motion of the wings had stopped.
How was a roc to know that there was no clean air anywhere?
