ABSOLUTELY NO PARADOX

The old men's section of the Arts and Science Club was always the best ordered. The robots somehow managed to avoid clanking there; the greensward beyond the veranda was always just right, and the drinks were the best for six counties. Old Ned Brussels touched his glass to his lips appreciatively, sighed in contentment, and waited for some of the other oldsters to break the silence.

Finally, Lem Hardy took the plunge. "He did it," he announced, referring to a conversation of weeks before. Then, at their puzzled looks, he amplified. "My grandson, damn it! He's got a time machine—it works. Sent a cat four days up, and it came through unharmed."

The glass fell from Old Ned's hand, bouncing on the floor, and spilling good liquor. A robot came forward silently to clean it up, but Ned didn't look at it. "Four days doesn't mean a thing. Lem—is that kid planning on trying it out?"

"He's going to try it next week."

"Then for the Lord's sake, stop him! Look, does it work like this?" His fingers slipped over the pencil smoothly, as they had always done when he worked, drafting robot bodies in the old days. A rude schematic seemed to grow almost instantly on the paper.

Lem took it, then stiffened suddenly. "Who told you?"

"A youngster named Pete LeFranc—and it was forty years ... no, over fifty years ago. Lem, if you like your grandson, keep him out of the machine. Four days, four weeks—they don't mean anything. Time machines don't work, however well they seem to."

A bustle from behind them pulled their eyes around. One of the robots was quietly restraining a nervous young man who was trying to break free and join the group. His face was tense, excited, with an odd bitter fear behind it. His words were seemingly cut out of steel. "... told me I'd find him here. Damn it...."

"Sorry, sir. You'll have to wait." The robot's voice was adamant under its smoothness.

Ned grunted, and then impulse led him to look again. He'd seen the man somewhere. He hunted for it, then dismissed it, knowing that his memory was tricky these days. But he motioned the robot aside. "We don't allow interruptions for junior members," he told the man, letting his voice soften the words. "Still, if you want to sit down and listen—quietly—nobody'll stop you."

"But...."

"Quietly!" The robot stressed the word. The man looked at it, then swiveled to Ned Brussels. For a moment, the bitterness halted, as if frozen, then gave place to a sudden sharp amusement. His eyes searched Ned's, and he nodded, dropping into a chair.

Lem took up the conversation again. "It worked. And if it works for four days, it should work for four centuries. You're just scared of paradoxes, Ned—going back and killing your grandfather, or such rot. You've been reading too many stories on it."

"Fifty years ago, Pete LeFranc said the same thing. Young man, either sit down, or get out! This is the Old Men's section! He had answers for all the paradoxes, too—except one question."

Ned had been young, then, just getting started at synthanatomy drafting, and not rich enough for wine of the type Pete always kept. He sipped it with relish, and looked at the odd cage Pete was displaying. "All the same, it won't work!"

Pete laughed. "Reality doesn't mean a thing to an artist, does it? Be damned to your paradoxes—there's some answer to them. It did work; the dog appeared exactly four weeks later, just finishing his bark!"

"Then why haven't time machines come back from the future?" Ned shot at him. He's been saving that as his final argument, and he sat back to watch the bomb explode.

For a second, Pete blinked. "You never figured that out yourself."

"Nope. I got it from a science fiction story. But why haven't they? If yours works, there'll be more time machines built. With more built, they'll be improved. They'll get to be commonplace. People'd use them—and someone would turn up here with one. Or in the past. Why haven't we met time travellers, Pete?"

"Maybe we have met them, but didn't know it?"

"Nonsense. You get in that machine and go back to Elizabethan England. Try to pass yourself off as being native to that time even an hour. No, there'd be slip-ups."

Pete considered it, pouring more wine. "An idea—but you're right, maybe. I haven't tried going back—if I'd sent the dog backwards, I couldn't have checked up on it, while I could be waiting in the future. Okay, you've convinced me."

"Then you're not going in the contraption."

Pete's laughter was spontaneous and loaded with amusement. "I'm going forward and find out why no one has come back! I've got a nice collection of rare coins I can trade off up there—should be more valuable—and I'll bring you back a working invention from the next century. With luck, I'll bring you the answer. And after that, maybe I can go back and kill an ancestor, just to see what happens."

"Don't be a fool!"

But Pete was grinning, and opening the door to the cage that rested in the middle of his laboratory. "Fifty years this trip," he said, spinning the dials. "And you won't have long to wait; I'll come back just about in no time."

Ned started to yell something, but there was a curious flicker, such as he'd seen when Pete sent the dog forward. The time machine blurred over, its surface seeming to stretch into infinity while contracting to nothing at the same time.

Then it was gone. Ned groped for the wine bottle, cursing, and drained the contents. Then he sat down to wait.

Three days later, the police came looking for Pete, on some mysterious tip, probably from a fellow worker. It was a pretty rough time, for a while, though they finally decided it was just another mystery, and that Ned's yarn of having been there only to keep an appointment was true. Ned had influential friends, even if he didn't have money, then.

For three years, he rented Pete's laboratory, before he made enough to buy it. For a decade, he lived in it; but by then he'd begun to know that Pete wasn't coming back.

"The building's still there," Old Ned finished. "The diagrams of his machine are still in the drawers. But Pete never showed up. I tell you, keep your fool grandson out of time machines, Lem. They don't work. Too many paradoxes—if they'd work, you could steal a future invention, get credit for inventing it, and nobody would ever have to invent it. When things have that many angles that can't work, the thing itself can't work."

Lem shook his head stubbornly. "It worked; the kid got the cat back. Something just happened to your friend—maybe his power failed."

"Then he wouldn't have gotten all the way—and he'd have reappeared years ago. Pete measured things—and there was no displacement in space. If something had happened to him, the machine would have been there, anyhow. Besides, I had alarms wired to call the police in—told 'em it was to protect a safe—the minute he showed up. He never showed up; he never came back."

"So I suppose he just disappeared—time ate him up?" Lem's stubbornness was cracking a bit, though. His voice was higher than even an old man's should be.

"I don't know. But time machines don't work. Otherwise where are the time travellers from the future?"

They sat quietly for a second. Ned was remembering the years, up to the time he'd given up, disconnected the alarms, and come here to the Arts and Science Club to live. He'd been stubborn, maybe—a little bit—but Pete hadn't reappeared.

Behind him, the young man cleared his throat, and the robot moved forward. But there was no rule against intrusion when no one was speaking, and the robot came to a stop. Ned looked back, just as the man decided the robot wouldn't interfere. There was more amusement on the man's face now, but the bitterness still lay there.

He grinned at Ned, a familiar grin, and his voice was flat and positive. "Time machines work. And there are no paradoxes—absolutely no paradoxes!"

Lem stirred, craning back, and Ned bristled. But something about the younger man caught back the words, as he picked up the thin thread of memory.

The other grinned again, wryly. "It's simple. Time machines work in one direction—they can't go back. Your time traveller found that out too late. No trips to the past, no return from the future—and no paradoxes, Ned Brussels."

He came to his feet, moving over to drop into the chair beside Ned. The older man nodded, stretching out his hand.

"I told you not to try the damned machine, Pete," Ned told him. Then he chuckled as the oldest cliche among old friends meeting again came to his lips. "Fifty years—and you haven't changed a bit, Pete LeFranc!"