"I see. Then it's your job to translate these symbols into words?"

"My job and that of other a.n.a.lysts. We use smaller, specially designed computers whenever necessary." Whistler smiled grimly. "Like the Delphic priestess of ancient Greece, Multivac gives oracular and obscure answers. Only we have translators, you see."

They had arrived. Meyerhof was waiting.

Whistler said briskly, "What circuits did you use, Grand Master?"

Meyerhof told him and Whistler went to work.

Trask tried to follow what was happening, but none of it made sense. The government official watched a spool unreel with a pattern of dots in endless incomprehensibility. Grand Master Meyerhof stood indifferently to one side while Whistler surveyed the pattern as it emerged. The a.n.a.lyst had put on headphones and a mouthpiece and at intervals murmured a series of instructions which, at some far-off place, guided a.s.sistants through electronic contortions in other computers.

Occasionally, Whistler listened, then punched combinations on a complex keyboard marked with symbols that looked vaguely mathematical but weren't.

A good deal more than an hour's time elapsed.

The frown on Whistler's face grew deeper. Once, he looked up at the two others and began, "This is unbel-" and turned back to his work.

Finally, he said hoa.r.s.ely, "I can give you an unofficial answer." His eyes were red-rimmed. "The official answer awaits complete a.n.a.lysis. Do you want it unofficial?"

"Go ahead," said Meyerhof.

Trask nodded.

Whistler darted a hangdog glance at the Grand Master. "Ask a foolish question-" he said. Then, gruffly, "Multivac says, extraterrestrial origin."

"What are you saying?" demanded Trask.

"Don't you hear me? The jokes we laugh at were not made up by any man. Multivac has a.n.a.lyzed all data given it and the one answer that best fits that data is that some extraterrestrial intelligence has composed the jokes, all of them, and placed them in selected human minds at selected times and places in such a way that no man is conscious of having made one up. All subsequent jokes are minor variations and adaptations of these grand originals."

Meyerhof broke in, face flushed with the kind of triumph only a Grand Master can know who once again has asked the right question. "All comedy writers," he said, "work by twisting old jokes to new purposes. That's well known. The answer fits."

"But why?" asked Trask. "Why make up the jokes?"

"Multivac says," said Whistler, "that the only purpose that fits all the data is that the jokes are intended to study human psychology. We study rat psychology by making the rats solve mazes. The rats don't know why and wouldn't even if they were aware of what was going on, which they're not. These outer intelligences study man's psychology by noting individual reactions to carefully selected anecdotes. Each man reacts differently.... Presumably, these outer intelligences are to us as we are to rats." He shuddered.

Trask, eyes staring, said, "The Grand Master said man is the only animal with a sense of humor. It would seem then that the sense of humor is foisted upon us from without."

Meyerhof added excitedly, "And for possible humor created from within, we have no laughter. Puns, I mean."

Whistler said, "Presumably, the extraterrestrials cancel out reactions to spontaneous jokes to avoid confusion."

Trask said in sudden agony of spirit, "Come on, now, Good Lord, do either of you believe this?"

The senior a.n.a.lyst looked at him coldly. "Multivac says so. It's all that can be said so far. It has pointed out the real jokesters of the universe, and if we want to know more, the matter will have to be followed up." He added in a whisper, "If anyone dares follow it up."

Grand Master Meyerhof said suddenly, "I asked two questions, you know. So far only the first has been answered. I think Multivac has enough data to answer the second."

Whistler shrugged. He seemed a half-broken man. "When a Grand Master thinks there is enough data," he said, "I'll make book on it. What is your second question?"

"I asked this. What will be the effect on the human race of discovering the answer to my first question?"

"Why did you ask that?" demanded Trask.

"Just a feeling that it had to be asked," said Meyerhof.

Trask said, "Insane. It's all insane," and turned away. Even he himself felt how strangely he and Whistler had changed sides. Now it was Trask crying insanity.

Trask closed his eyes. He might cry insanity all he wished, but no man in fifty years had doubted the combination of a Grand Master and Multivac and found his doubts verified.

Whistler worked silently, teeth clenched. He put Multivac and its subsidiary machines through their paces again. Another hour pa.s.sed and he laughed harshly. "A raving nightmare!"

"What's the answer?" asked Meyerhof. "I want Multivac's remarks, not yours."

"All right. Take it. Multivac states that, once even a single human discovers the truth of this method of psychological a.n.a.lysis of the human mind, it will become useless as an objective technique to those extraterrestrial powers now using it."

"You mean there won't be any more jokes handed out to humanity?" asked Trask faintly. "Or what do you mean?"

"No more jokes," said Whistler, "now! Multivac says now now! The experiment is ended now now! A new technique will have to be introduced."

They stared at each other. The minutes pa.s.sed.

Meyerhof said slowly, "Multivac is right."

Whistler said haggardly, "I know."

Even Trask said in a whisper, "Yes. It must be."

It was Meyerhof who put his finger on the proof of it, Meyerhof the accomplished jokester. He said, "It's over, you know, all over. I've been trying for five minutes now and I can't think of one single joke, not one! And if I read one in a book, I wouldn't laugh. I know."

"The gift of humor is gone," said Trask drearily. "No man will ever laugh again."

And they remained there, staring, feeling the world shrink down to the dimensions of an experimental rat cage-with the maze removed and something, something about to be put in its place.

The Last Question

The last question was asked for the first time, half in jest, on May 21, 2061, at a time when humanity first stepped into the light. The question came about as a result of a five-dollar bet over highb.a.l.l.s, and it happened this way: Alexander Adell and Bertram Lupov were two of the faithful attendants of Multivac. As well as any human beings could, they knew what lay behind the cold, clicking, flashing face-miles and miles of face-of that giant computer. They had at least a vague notion of the general plan of relays and circuits that had long since grown past the point where any single human could possibly have a firm grasp of the whole.

Multivac was self-adjusting and self-correcting. It had to be, for nothing human could adjust and correct it quickly enough or even adequately enough. So Adell and Lupov attended the monstrous giant only lightly and superficially, yet as well as any men could. They fed it data, adjusted questions to its needs and translated the answers that were issued. Certainly they, and all others like them, were fully ent.i.tled to share in the glory that was Multivac's.

For decades, Multivac had helped design the ships and plot the trajectories that enabled man to reach the Moon, Mars, and Venus, but past that, Earth's poor resources could not support the ships. Too much energy was needed for the long trips. Earth exploited its coal and uranium with increasing efficiency, but there was only so much of both.

But slowly Multivac learned enough to answer deeper questions more fundamentally, and on May 14, 2061, what had been theory, became fact.

The energy of the sun was stored, converted, and utilized directly on a planet-wide scale. All Earth turned off its burning coal, its fissioning uranium, and flipped the switch that connected all of it to a small station, one mile in diameter, circling the Earth at half the distance of the Moon. All Earth ran by invisible beams of sunpower.

Seven days had not sufficed to dim the glory of it and Adell and Lupov finally managed to escape from the public function, and to meet in quiet where no one would think of looking for them, in the deserted underground chambers, where portions of the mighty buried body of Multivac showed. Unattended, idling, sorting data with contented lazy clickings, Multivac, too, had earned its vacation and the boys appreciated that. They had no intention, originally, of disturbing it.

They had brought a bottle with them, and their only concern at the moment was to relax in the company of each other and the bottle.

"It's amazing when you think of it," said Adell. His broad face had lines of weariness in it, and he stirred his drink slowly with a gla.s.s rod, watching the cubes of ice slur clumsily about. "All the energy we can possibly ever use for free. Enough energy, if we wanted to draw on it, to melt all Earth into a big drop of impure liquid iron, and still never miss the energy so used. All the energy we could ever use, forever and forever and forever."

Lupov c.o.c.ked his head sideways. He had a trick of doing that when he wanted to be contrary, and he wanted to be contrary now, partly because he had had to carry the ice and gla.s.sware. "Not forever," he said.

"Oh, h.e.l.l, just about forever. Till the sun runs down, Bert."

"That's not forever."

"All right, then. Billions and billions of years. Twenty billion, maybe. Are you satisfied?"

Lupov put his fingers through his thinning hair as though to rea.s.sure himself that some was still left and sipped gently at his own drink. "Twenty billion years isn't forever."

"Well, it will last our time, won't it?"

"So would the coal and uranium."

"All right, but now we can hook up each individual s.p.a.ceship to the Solar Station, and it can go to Pluto and back a million times without ever worrying about fuel. You can't do that that on coal and uranium. Ask Multivac, if you don't believe me." on coal and uranium. Ask Multivac, if you don't believe me."

"I don't have to ask Multivac. I know that."

"Then stop running down what Multivac's done for us," said Adell, blazing up. "It did all right."

"Who says it didn't? What I say is that a sun won't last forever. That's all I'm saying. We're safe for twenty billion years, but then what?" Lupov pointed a slightly shaky finger at the other. "And don't say we'll switch to another sun."

There was silence for a while. Adell put his gla.s.s to his lips only occasionally, and Lupov's eyes slowly closed. They rested.

Then Lupov's eyes snapped open. "You're thinking we'll switch to another sun when ours is done, aren't you?"

"I'm not thinking."

"Sure you are. You're weak on logic, that's the trouble with you. You're like the guy in the story who was caught in a sudden shower and who ran to a grove of trees and got under one. He wasn't worried, you see, because he figured when one tree got wet through, he would just get under another one."

"I get it," said Adell. "Don't shout. When the sun is done, the other stars will be gone, too."

"Darn right they will," muttered Lupov. "It all had a beginning in the original cosmic explosion, whatever that was, and it'll all have an end when all the stars run down. Some run down faster than others. h.e.l.l, the giants won't last a hundred million years. The sun will last twenty billion years and maybe the dwarfs will last a hundred billion for all the good they are. But just give us a trillion years and everything will be dark. Entropy has to increase to maximum, that's all."

"I know all about entropy," said Adell, standing on his dignity.

"The h.e.l.l you do."

"I know as much as you do."

"Then you know everything's got to run down someday."

"AU right. Who says they won't?"

"You did, you poor sap. You said we had all the energy we needed, forever. You said 'forever.' "

It was Adell's turn to be contrary. "Maybe we can build things up again someday," he said.

"Never."

"Why not? Someday."

"Never."

"Ask Multivac."

"You ask Multivac. I dare you. Five dollars says it can't be done." ask Multivac. I dare you. Five dollars says it can't be done."

Adell was just drunk enough to try, just sober enough to be able to phrase the necessary symbols and operations into a question which, in words, might have corresponded to this: Will mankind one day without the net expenditure of energy be able to restore the sun to its full youthfulness even after it had died of old age?

Or maybe it could be put more simply like this: How can the net amount of entropy of the universe be ma.s.sively decreased?

Multivac fell dead and silent. The slow flashing of lights ceased, the distant sounds of clicking relays ended.

Then, just as the frightened technicians felt they could hold their breath no longer, there was a sudden springing to life of the teletype attached to that portion of Multivac. Five words were printed: insufficient data for meaningful answer.

"Not yet," whispered Lupov. They left hurriedly. By next morning, the two, plagued with throbbing head and cottony mouth, had forgotten the incident.

Jerrodd, Jerrodine, and Jerrodette I and II watched the starry picture in the visiplate change as the pa.s.sage through hypers.p.a.ce was completed in its non-time lapse. At once, the even powdering of stars gave way to the predominance of a single bright marble-disk, centered.

"That's X-23," said Jerrodd confidently. His thin hands clamped tightly behind his back and the knuckles whitened.

The little Jerrodettes, both girls, had experienced the hypers.p.a.ce pa.s.sage for the first time in their lives and were self-conscious over the momentary sensation of inside-outness. They buried their giggles and chased one another wildly about their mother, screaming, "We've reached X-23-we've reached X-23-we've-"

"Quiet, children," said Jerrodine sharply. "Are you sure, Jerrodd?"

"What is there to be but sure?" asked Jerrodd, glancing up at the bulge of featureless metal just under the ceiling. It ran the length of the room, disappearing through the wall at either end. It was as long as the ship.

Jerrodd scarcely knew a thing about the thick rod of metal except that it was called a Microvac, that one asked it questions if one wished; that if one did not it still had its task of guiding the ship to a preordered destination; of feeding on energies from the various Sub-galactic Power Stations; of computing the equations for the hyperspatial jumps.

Jerrodd and his family had only to wait and live in the comfortable residence quarters of the ship.

Someone had once told Jerrodd that the "ac" at the end of "Microvac" stood for "a.n.a.log computer" in ancient English, but he was on the edge of forgetting even that.

Jerrodine's eyes were moist as she watched the visiplate. "I can't help it. I feel funny about leaving Earth."

"Why, for Pete's sake?" demanded Jerrodd. "We had nothing there. We'll have everything on X-23. You won't be alone. You won't be a pioneer. There are over a million people on the planet already. Good Lord, our great-grandchildren will be looking for new worlds because X-23 will be overcrowded." Then, after a reflective pause, "I tell you, it's a lucky thing the computers worked out interstellar travel the way the race is growing."

"I know, I know," said Jerrodine miserably.

Jerrodette I said promptly, "Our Microvac is the best Microvac in the world."

"I think so, too," said Jerrodd, tousling her hair.