HINDSIGHT

by Jack Williamson

SOMETHING WAS WRONG WITH THE CIGAR.

But Brek Veronar didn't throw it away. Earth‑grown tobacco was precious, here on Ceres. He took another bite off the end, and pressed the lighter cone again. This time, imperfectly, the cigar drew‑‑with an acrid, puzzling odor of scorching paper.

Brek Veronar‑‑born William Webster, Earthman‑‑was sitting in his big, well‑furnished office, adjoining the arsenal laboratory. Beyond the perdurite windows, magnified in the crystalline clarity of the asteroid's synthetic atmosphere, loomed a row of the immense squat turret forts that guarded the Astrophon base‑‑their mighty twenty‑four‑inch rifles, coupled to the Veronar autosight, covered with their theoretical range everything within Jupiter's orbit. A squadron of the fleet lay on the field beyond, seven tremendous dead‑black cigar shapes. Far off, above the rugged red palisades of a second plateau, stood the many‑colored domes and towers of Astrophon itself, the Astrarch's capital.

A tall, gaunt man, Brek Veronar wore the bright, close‑fitting silks of the Astrarchy. Dyed to conceal the increasing streaks of gray, his hair was perfumed and curled. In abrupt contrast to the force of his gray, wide‑set eyes, his face was white and smooth from cosmetic treatments. Only the cigar could have betrayed him as a native of Earth, and Brek Veronar never smoked except here in his own locked laboratory.

He didn't like to be called the Renegade.

Curiously, that whiff of burning paper swept his mind away from the intricate drawing of a new rocket‑torpedo gyropilot pinned to a board on the desk before him, and back across twenty years of time. It returned him to the university campus, on the low yellow hills beside the ancient Martian city of Toran‑‑to the fateful day when Bill Webster had renounced allegiance to his native Earth, for the Astrarch.

Tony Grimm and Elora Ronee had both objected. Tony was the freckled, irresponsible redhead who had come out from Earth with him six years before, on the other of the two annual engineering scholarships. Elora Ronee was the lovely dark‑eyed Martian girl‑‑daughter of the professor of geodesics, and a proud descendant of the first colonists‑whom they both loved.

He walked with them, that dry, bright afternoon, out from the yellow adobe buildings, across the rolling, stony, ocher‑colored desert. Tony's sunburned, blue‑eyed face was grave for once, as he protested.

"You can't do it, Bill. No Earthman could."

"No use talking," said Bill Webster, shortly. "The Astrarch wants a military engineer. His agents offered me twenty thousand eagles a year, with raises and bonuses‑‑ten times what any research scientist could hope to get, back on Earth."

The tanned, vivid face of Elora Ronee looked hurt. "Bill‑‑what about your own research?" the slender girl cried. "Your new reaction tube! You promised you were going to break the Astrarch's monopoly on space transport. Have you forgotten?"

"The tube was just a dream," Bill Webster told her, "but probably it's the reason he offered the contract to me, and not Tony. Such jobs don't go begging."

Tony caught his arm. "You can't turn against your own world, Bill," he insisted. "You can't give up everything that means anything to an Earthman. Just remember what the Astrarch is‑‑a superpirate."

Bill Webster's toe kicked up a puff of yellow dust. "I know history," he said. "I know that the Astrarchy had its beginnings from the space pirates who established their bases in the asteroids, and gradually turned to commerce instead of raiding."

His voice was injured and defiant. "But, so far as I'm concerned, the Astrarchy is just as respectable as such planet nations as Earth and Mars and the Jovian Federation. And it's a good deal more wealthy and powerful than any of them."

Tense‑faced, the Martian girl shook her dark head. "Don't blind yourself, Bill," she begged urgently. "Can't you see that the Astrarch really is no different from any of the old pirates? His fleets still seize any independent vessel, or make the owners ransom it with his space‑patrol tax."

She caught an indignant breath. "Everywhere‑‑even here on Mars‑-the agents and residents and traders of the Astrarch have brought graft and corruption and oppression. The Astrarch is using his wealth and his space power to undermine the government of every independent planet. He's planning to conquer the system!"

Her brown eyes flashed. "You won't aid him, Bill. You‑‑couldn't!" Bill Webster looked into the tanned, intent loveliness of her face‑he wanted suddenly to kiss the smudge of yellow dust on her impudent little nose. He had loved Elora Ronee, had once hoped to take her back to Earth. Perhaps he still loved her. But now it was clear that she had always wanted Tony Grimm.

Half angrily, he kicked an iron‑reddened pebble. "If things had been different, Elora, it might have been‑‑" With an abrupt little shrug, he looked back at Tony. "Anyhow," he said flatly, "I'm leaving for Astrophon tonight."

That evening, after they had helped him pack, he made a bonfire of his old books and papers. They burned palely in the thin air of Mars, with a cloud of acrid smoke.

That sharp odor was the line that had drawn Brek Veronar back across the years, when his nostrils stung to the scorched‑paper scent. The cigar came from a box that had just arrived from Cuba, Earth‑‑made to his special order.

He could afford such luxuries. Sometimes, in fact, he almost regretted the high place he had earned in the Astrarch's favor. The space officers, and even his own jealous subordinates in the arsenal laboratory, could never forget that he was an Earthman‑‑the Renegade.

The cigar's odor puzzled him.

Deliberately, he crushed out the smoldering tip, peeled off the brown wrapper leaves. He found a tightly rolled paper cylinder. Slipping off the rubber bands, he opened it. A glimpse of the writing set his heart to thudding.

It was the hand of Elora Ronee!

Brek Veronar knew that fine graceful script. For once Bill Webster had treasured a little note that she had written him, when they were friends at school. He read it eagerly:

DEAR BILL:

This is the only way we can hope to get word to you, past the Astrarch's spies. Your old name, Bill, may seem strange to you. But we‑‑Tony and I‑‑want you to remember that you are an Earthman.

You can't know the oppression that Earth now is suffering, under the Astrarch's heel. But independence is almost gone. Weakened and corrupted, the government yields everywhere. Every Earthman's life is choked with taxes and unjust penalties and the unfair competition of the Astrarch traders.

But Earth, Bill, has not completely yielded. We are going to strike for liberty. Many years of our lives‑‑Tony's and mine‑‑have gone into the plan. And the toil and the sacrifices of millions of our fellow Earthmen. We have at least a chance to recover our lost freedom.

But we need you, Bill‑‑desperately.

For your own world's sake, come back. Ask for a vacation trip to Mars. The Astrarch will not deny you that. On April 8th, a ship will be waiting for you in the desert outside Toran‑‑where we walked the day you left.

Whatever your decision, Bill, we trust you to destroy this letter and keep its contents secret. But we believe that you will come back. For Earth's sake, and for your old friends,

TONY AND ELORA.

Brek Veronar sat for a long time at his desk, staring at the charred, wrinkled sheet. His eyes blurred a little, and he saw the tanned vital face of the Martian girl, her brown eyes imploring. At last he sighed and reached slowly for the lighter cone. He held the letter until the flame had consumed it.

Next day four space officers came to the laboratory. They were insolent in the gaudy gold and crimson of the Astrarch, and the voice of the captain was suave with a triumphant hate:

"Earthman, you are under technical arrest, by the Astrarch's order. You will accompany us at once to his quarters aboard the Warrior Queen."

Brek Veronar knew that he was deeply disliked, but very seldom had the feeling been so openly shown. Alarmed, he locked his office and went with the four.

Flagship of the Astrarch's space fleets, the Warrior Queen lay on her cradle, at the side of the great field beyond the low gray forts. A thousand feet and a quarter of a million tons of fighting metal, with sixty‑four twenty‑inch rifles mounted in eight bulging spherical turrets, she was the most powerful engine of destruction the system had ever seen.

Brek Veronar's concern was almost forgotten in a silent pride, as a swift electric car carried them across the field. It was his autosight‑‑otherwise the Veronar achronic field detector geodesic achron‑integration self-calculating range finder‑‑that directed the fire of those mighty guns. It was the very fighting brain of the ship‑‑of all the Astrarch's fleet.

No wonder these men were jealous.

"Come, Renegade!" The bleak‑faced captain's tone was ominous. "The Astrarch is waiting."

Bright‑uniformed guards let them into the Astrarch's compact but luxurious suite, just aft the console room and forward of the autosight installation, deep in the ship's armored bowels. The Astrarch turned from a chart projector, and crisply ordered the two officers to wait outside.

"Well, Veronar?"

A short, heavy, compact man, the dictator of the Astrarchy was vibrant with a ruthless energy. His hair was waved and perfumed, his face a rouged and powdered mask, his silk‑swathed figure loaded with jewels. But nothing could hide the power of his hawklike nose and his burning black eyes.

The Astrarch had never yielded to the constant pressure of jealousy against Brek Veronar. The feeling between them had grown almost to friendship. But now the Earthman sensed, from the cold inquiry of those first words, and the probing flash of the ruler's eyes, that his position was gravely dangerous.

Apprehension strained his voice. "I'm under arrest?"

The Astrarch smiled, gripped his hand. "My men are overzealous, Veronar." The voice was warm, yet Brek Veronar could not escape the sense of something sharply critical, deadly. "I merely wish to talk with you, and the impending movements of the fleet allowed little time."

Behind that smiling mask, the Astrarch studied him. "Veronar, you have served me loyally. I am leaving Astrophon for a cruise with the fleet, and I feel that you, also, have earned a holiday. Do you want a vacation from your duties here‑‑let us say, to Mars?"

Beneath those thrusting eyes, Brek Veronar flinched. "Thank you, Gorro," he gulped‑‑he was among the few privileged to call the Astrarch by name. "Later, perhaps. But the torpedo guide isn't finished. And I've several ideas for improving the autosight. I'd much prefer to stay in the laboratory."

For an instant, the short man's smile seemed genuine. "The Astrarchy is indebted to you for the autosight. The increased accuracy of fire has in effect quadrupled our fleets." His eyes were sharp again, doubtful. "Are further improvements possible?"

Brek Veronar caught his breath. His knees felt a little weak. He knew that he was talking for his life. He swallowed, and his words came at first unsteadily.

"Geodesic analysis and integration is a completely new science," he said desperately. "It would be foolish to limit the possibilities. With a sufficiently delicate pick‑up, the achronic detector fields ought to be able to trace the world lines of any object almost indefinitely. Into the future‑‑"

He paused for emphasis. "Or into the past!"

An eager interest flashed in the Astrarch's eyes. Brek felt confidence returning. His breathless voice grew smoother.

"Remember, the principle is totally new. The achronic field can be made a thousand times more sensitive than any telescope‑‑I believe, a million times! And the achronic beam eliminates the time lag of all electromagnetic methods of observation. Timeless, paradoxically it facilitates the exploration of time."

"Exploration?" questioned the dictator. "Aren't you speaking rather wildly, Veronar?"

"Any range finder, in a sense, explores time," Brek assured him urgently. "It analyzes the past to predict the future‑‑so that a shell fired from a moving ship and deflected by the gravitational fields of space may move thousands of miles to meet another moving ship, minutes in the future.

"Instruments depending on visual observation and electromagnetic transmission of data were not very successful. One hit in a thousand used to be good gunnery. But the autosight has solved the problem‑‑now you reprimand gunners for failing to score two hits in a hundred."

Brek caught his breath. "Even the newest autosight is just a rough beginning. Good enough, for a range finder. But the detector fields can be made infinitely more sensitive, the geodesic integration infinitely more certain.

"It ought to be possible to unravel the past for years, instead of minutes. It ought to be possible to foretell the position of a ship for weeks ahead‑to anticipate every maneuver, and even watch the captain eating his breakfast!"

The Earthman was breathless again, his eyes almost feverish. "From geodesic analysis," he whispered, "there is one more daring step‑‑control. You are aware of the modern view that there is no absolute fact, but only probability. I can prove it! And probability can be manipulated, through pressure of the achronic field.

"It is possible, even, I tell you‑‑"

Brek's rushing voice faltered. He saw that doubt had drowned the flash of interest in the Astrarch's eyes. The dictator made an impatient gesture for silence. In a flat, abrupt voice he stated: "Veronar, you are an Earthman."

"Once I was an Earthman."

The black, flashing eyes probed into him. "Veronar," the Astrarch said, "trouble is coming with Earth. My agents have uncovered a dangerous plot. The leader of it is an engineer named Grimm, who has a Martian wife. The fleet is moving to crush the rebellion." He paused. "Now, do you want the vacation?"

Before those ruthless eyes, Brek Veronar stood silent. Life, he was now certain, depended on his answer. He drew a long, unsteady breath. "No," he said.

Still the Astrarch's searching tension did not relax. "My officers," he said, "have protested against serving with you, against Earth. They are suspicious."

Brek Veronar swallowed. "Grimm and his wife," he whispered hoarsely, "once were friends of mine. I had hoped that it would not be necessary to betray them. But I have received a message from them."

He gulped again, caught his breath. "To prove to your men that I am no longer an Earthman‑‑a ship that they have sent for me v.ill be waiting, on April 8th, Earth calendar, in the desert south of the Martian city of Toran."

The white, lax mask of the Astrarch smiled. "I'm glad you told me, Veronar," he said. "You have been very useful‑‑and I like you. Now I can tell you that my agents read the letter in the cigar. The rebel ship was overtaken and destroyed by the space patrol, just a few hours ago."

Brek Veronar swayed to a giddy weakness.

"Entertain no further apprehensions." The Astrarch touched his arm. "You will accompany the fleet, in charge of the autosight. We take off in five hours."

The long black hull of the Warrior Queen lifted on flaring reaction tubes, leading the squadron. Other squadrons moved from the bases on Pallas, Vesta, Thule, and Eros. The Second Fleet came plunging Sunward from its bases on the Trojan planets. Four weeks later, at the rendezvous just within the orbit of Mars, twenty‑nine great vessels had come together.

The armada of the Astrarchy moved down upon Earth.

Joining the dictator in his chartroom, Brek was puzzled. "Still I don't see the reason for such a show of strength," he said. "Why have you gathered three fourths of your space forces, to crush a handful of plotters?"

"We have to deal with more than a handful of plotters." Behind the pale mask of the Astrarch's face, Brek could sense a tension of worry. "Millions of Earthmen have labored for years to prepare for this rebellion. Earth has built a space fleet."

Brek was astonished. "A fleet?"

"The parts were manufactured secretly, mostly in underground mills," the Astrarch told him. "The ships were assembled by divers, under the surface of fresh‑water lakes. Your old friend, Grimm, is clever and dangerous. We shall have to destroy his fleet, before we can bomb the planet into submission."

Steadily, Brek met the Astrarch's eyes. "How many ships?" he asked.

"Six."

"Then we outnumber them five to one." Brek managed a confident smile. "Without considering the further advantage of the autosight. It will be no battle at all."

"Perhaps not," said the Astrarch, "but Grimm is an able man. He has invented a new type reaction tube, in some regards superior to our own." His dark eyes were somber. "It is Earthman against Earthman," he said softly. "And one of you shall perish."

Day after day, the armada dropped Earthward.

The autosight served also as the eyes of the fleet, as well as the fighting brain. In order to give longer base lines for the automatic triangulations, additional achronic‑field pick‑ups had been installed upon half a dozen ships. Tight achronic beams brought their data to the immense main instrument, on the Warrior Queen. The autosight steered every ship, by achronic beam control, and directed the fire of its guns.

The Warrior Queen led the fleet. The autosight held the other vessels in accurate line behind her, so that only one circular cross section might be visible to the telescopes of Earth.

The rebel planet was still twenty million miles ahead, and fifty hours at normal deceleration, when the autosight discovered the enemy fleet.

Brek Veronar sat at the curving control table.

Behind him, in the dim‑lit vastness of the armored room, bulked the main instrument. Banked thousands of green‑painted cases‑‑the intricate cells of the mechanical brain‑‑whirred with geodesic analyzers and integrators. The achronic field pick‑ups‑‑sense organs of the brain‑‑were housed in insignificant black boxes. And the web of achronic transmission beams‑‑instantaneous, ultrashort, nonelectromagnetic waves of the subelectronic order‑‑the nerve fibers that joined the busy cells‑‑was quite invisible.

Before Brek stood the twenty‑foot cube of the stereoscreen, through which the brain communicated its findings. The cube was black, now, with the crystal blackness of space. Earth, in it, made a long misty crescent of wavering crimson splendor. The Moon was a smaller scimitar, blue with the dazzle of its artificial atmosphere.

Brek touched intricate controls. The Moon slipped out of the cube. Earth grew‑‑and turned. So far had the autosight conquered time and space. It showed the planet's Sunward side.

Earth filled the cube, incredibly real. The vast white disk of one low-pressure area lay upon the Pacific's glinting blue. Another, blotting out the winter brown of North America, reached to the bright gray cap of the arctic.

Softly, in the dim room, a gong clanged. Numerals of white fire flickered against the image in the cube. An arrow of red flame pointed. At its point was a tiny fleck of black.

The gong throbbed again, and another black mote came up out of the clouds. A third followed. Presently there were six. Watching, Brek Veronar felt a little stir of involuntary pride, a dim numbness of regret.

Those six vessels were the mighty children of Tony Grimm and Elora, the fighting strength of Earth. Brek felt an aching tenseness in his throat, and tears stung his eyes. It was too bad that they had to be destroyed.

Tony would be aboard one of those ships. Brek wondered how he would look, after twenty years. Did his freckles still show? Had he grown stout? Did concentration still plow little furrows between his blue eyes?

Elora‑‑would she be with him? Brek knew she would. His mind saw the Martian girl, slim and vivid and intense as ever. He tried to thrust away the image. Time must have changed her. Probably she looked worn from the years of toil and danger; her dark eyes must have lost their sparkle.

Brek had to forget that those six little blots represented the lives of Tony and Elora, and the independence of the Earth. They were only six little lumps of matter, six targets for the autosight.

He watched them, rising, swinging around the huge, luminous curve of the planet. They were only six mathematical points, tracing world lines through the continuum, making a geodesic pattern for the analyzers to unravel and the integrators to project against the future‑

The gong throbbed again.

Tense with abrupt apprehension, Brek caught up a telephone.

"Give me the Astrarch.... An urgent report.... No, the admiral won't do.... Gorro, the autosight has picked up the Earth fleet ... Yes, only six ships, just taking off from the Sunward face. But there is one alarming thing."

Brek Veronar was hoarse, breathless. "Already, behind the planet, they have formed a cruising line. The axis extends exactly in our direction. That means that they know our precise position, before they have come into telescopic view. That suggests that Tony Grimm has invented an autosight of his own!"

Strained hours dragged by. The Astrarch's fleet decelerated, to circle and bombard the mother world, after the battle was done. The Earth ships came out at full normal acceleration.

"They must stop," the Astrarch said. "That is our advantage. If they go by us at any great velocity, we'll have the planet bombed into submission before they can return. They must turn back‑‑and then we'll pick them off."

Puzzlingly, however, the Earth fleet kept up acceleration, and a slow apprehension grew in the heart of Brek Veronar. There was but one explanation. The Earthmen were staking the life of their planet on one brief encounter.

As if certain of victory!

The hour of battle neared. Tight achronic beams relayed telephoned orders from the Astrarch's chartroom, and the fleet deployed into battle formation‑‑into the shape of an immense shallow bowl, so that every possible gun could be trained upon the enemy.

The hour‑‑and the instant!

Startling in the huge dim space that housed the autosight, crackling out above the whirring of the achron‑integrator, the speaker that was the great brain's voice counted off the minutes.

"Minus four‑‑"

The autosight was set, the pick‑ups tuned, the director relays tested, a thousand details checked. Behind the control table, Brek Veronar tried to relax. His part was done.

A space battle was a conflict of machines. Human beings were too puny, too slow, even to comprehend the play of the titanic forces they had set loose. Brek tried to remember that he was the autosight's inventor; he fought an oppression of helpless dread.

"Minus three‑‑"

Sodium bombs filled the void ahead with vast silver plumes and streamers‑‑for the autosight removed the need of telescopic eyes, and enabled ships to fight from deep smoke screens.

"Minus two‑‑"

The two fleets came together at a relative velocity of twelve hundred thousand miles an hour. Maximum useful range of twenty-inch guns, even with the autosight, was only twenty thousand miles in free space.

Which meant, Brek realized, that the battle could last just two minutes.

In that brief time lay the destinies of Astrarchy and Earth‑‑and Tony Grimm's and Elora's and his own.

"Minus one‑‑"

The sodium screens made little puffs and trails of silver in the great black cube. The six Earth ships were visible behind them, through the magic of the achronic field pick‑ups, now spaced in a close ring, ready for action.

Brek Veronar looked down at the jeweled chronometer on his wrist‑a gift from the Astrarch. Listening to the rising hum of the achron-integrators, he caught his breath, tensed instinctively.

"Zero!"

The Warrior Queen began quivering to her great guns, a salvo of four firing every half‑second. Brek breathed again, watching the chronometer. That was all he had to do. And in two minutes‑

The vessel shuddered, and the lights went out. Sirens wailed, and air valves clanged. The lights came on, went off again. And abruptly the cube of the stereo screen was dark. The achron‑integrators clattered and stopped.

The guns ceased to thud.

'Power!" Brek gasped into a telephone. "Give me power! Emergency! The autosight has stopped and‑‑"

But the telephone was dead.

There were no more hits. Smothered in darkness, the great room remained very silent. After an etemal time, feeble emergency lights came on. Brek looked again at his chronometer, and knew that the battle was ended.

But who the victor?

He tried to hope that the battle had been won before some last chance broadside crippled the flagship‑‑until the Astrarch came stumbling into the room, looking dazed and pale.

"Crushed," he muttered. "You failed me, Veronar."

"What are the losses?" whispered Brek.

"Everything." The shaken ruler dropped wearily at the control table. "Your achronic beams are dead. Five ships remain able to report defeat by radio. Two of them hope to make repairs.

"The Queen is disabled. Reaction batteries shot away, and main power plant dead. Repair is hopeless. And our present orbit will carry us far too close to the Sun. None of our ships able to undertake rescue. We'll be baked alive."

His perfumed dark head sank hopelessly. "In those two minutes, the Astrarchy was destroyed." His hollow, smoldering eyes lifted resentfully to Brek. "Just two minutes!" He crushed a soft white fist against the table. "If time could be recaptured‑‑"

"How were we beaten?" demanded Brek. "I can't understand!"

"Marksmanship," said the tired Astrarch. "Tony Grimm has something better than your autosight. He shot us to pieces before we could find the range." His face was a pale mask of bitterness. "If my agents had employed him, twenty years ago, instead of you‑‑" He bit blood from his lip. "But the past cannot be changed."

Brek was staring at the huge, silent bulk of the autosight. "Perhaps" ‑‑he whispered‑‑"it can be!"

Trembling, the Astrarch rose to clutch his arm. "You spoke of that before," gasped the agitated ruler. "Then I wouldn't listen. But now‑try anything you can, Veronar. To save us from roasting alive, at perihelion. Do you really think‑‑"

The Astrarch shook his pale head. "I'm the madman," he whispered. "To speak of changing even two minutes of the past!" His hollow eyes clung to Brek. "Though you have done amazing things, Veronar."

The Earthman continued to stare at his huge creation. "The autosight itself brought me one clue, before the battle," he breathed slowly. "The detector fields caught a beam of Tony Grimm's, and analyzed the frequencies. He's using achronic radiation a whole octave higher than anything I've tried. That must be the way to the sensitivity and penetration I have hoped for."

Hope flickered in the Astrarch's eyes. "You believe you can save us? How?"

"If the high‑frequency beam can search out the determiner factors," Brek told him, "it might be possible to alter them, with a sufficiently powerful field. Remember that we deal with probabilities, not with absolutes. And that small factors can determine vast results.

"The pick‑ups will have to be rebuilt. And we'll have to have power. Power to project the tracer fields. And a river of power‑‑if we can trace out a decisive factor and attempt to change it. But the power plants are dead.

"Rebuild your pick‑ups," the Astrarch told him. "And you'll have power ‑‑if I have to march every man aboard into the conversion furnaces, for fuel."

Calm again, and confident, the short man surveyed the tall, gaunt Earthman with wondering eyes.

"You're a strange individual, Veronar," he said. "Fighting time and destiny to crush the planet of your birth! It isn't strange that men call you the Renegade."

Silent for a moment, Brek shook his haggard head. "I don't want to be baked alive," he said at last. "Give me power‑‑and we'll fight that battle again."

The wreck dropped Sunward. A score of expert technicians toiled, under Brek's expert direction, to reconstruct the achronic pick‑ups. And a hundred men labored, beneath the ruthless eye of the Astrarch himself, to repair the damaged atomic converters.

They had crossed the orbit of Venus, when the autosight came back to humming life. The Astrarch was standing beside Brek, at the curved control table. The shadow of doubt had returned to his reddened, sleepless eyes. "Now," he demanded, "what can you do about the battle?"

"Nothing, directly," Brek admitted. "First we must search the past. We must find the factor that caused Tony Grimm to invent a better autosight than mine. With the high‑frequency field‑‑and the full power of the ship's converters, if need be‑‑we must reverse that factor. Then the battle should have a different outcome."

The achron‑integrators whirred, as Brek manipulated the controls, and the huge black cube began to flicker with the passage of ghostly images. Symbols of colored fire flashed and vanished within it.

"Well" anxiously rasped the Astrarch.

"It works!" Brek assured him. "The tracer fields are following all the world lines that intersected at the battle, back across the months and years. The analyzers will isolate the smallest‑‑and hence most easily altered‑‑essential factor."

The Astrarch gripped his shoulder. "There‑‑in the cube‑‑yourself!"

The ghostly shape of the Earthman flickered out, and came again. A hundred times, Brek Veronar glimpsed himself in the cube. Usually the scene was the great arsenal laboratory, at Astrophon. Always he was differently garbed, always younger.

Then the background shifted. Brek caught his breath as he recognized glimpses of barren, stony, ocher‑colored hills, and low, yellow adobe buildings. He gasped to see a freckled, red‑haired youth and a slim, tanned, dark‑eyed girl.

"That's on Mars!" he whispered. "At Toran. He's Tony Grimm. And she's Elora Ronee‑‑the Martian girl we loved."

The racing flicker abruptly stopped, upon one frozen tableau. A bench on the dusty campus, against a low adobe wall. Elora Ronee, with a pile of books propped on her knees to support pen and paper. Her dark eyes were staring away across the campus, and her sun‑brown face looked tense and troubled.

In the huge dim room aboard the wrecked warship, a gong throbbed softly. A red arrow flamed in the cube, pointing down at the note on the girl's knee. Cryptic symbols flashed above it. And Brek realized that the humming of the achron‑integrators had stopped.

"What's this?" rasped the anxious Astrarch. "A schoolgirl writing a note‑‑what has she to do with a space battle?"

Brek scanned the fiery symbols. "She was deciding the battle‑‑that day twenty years ago!" His voice rang with elation. "You see, she had a date to go dancing in Toran with Tony Grimm that night. But her father was giving a special lecture on the new theories of achronic force. Tony broke the date, to attend the lecture."

As Brek watched the motionless image in the cube, his voice turned a little husky. "Elora was angry‑‑that was before she knew Tony very well. I had asked her for a date. And, at the moment you see, she has just written a note, to say that she would go dancing with me."

Brek gulped. "But she is undecided, you see. Because she loves Tony. A very little would make her tear up the note to me, and write another to Tony, to say that she would go to the lecture with him."

The Astrarch stared cadaverously. "But how could that decide the battle?"

"In the past that we have lived," Brek told him, "Elora sent the note to me. I went dancing with her, and missed the lecture. Tony attended it‑‑and got the germ idea that finally caused his autosight to be better than mine.

"But, if she had written to Tony instead, he would have offered, out of contrition, to cut the lecture‑‑so the analyzers indicate. I should have attended the lecture in Tony's place, and my autosight would have been superior in the end."

The Astrarch's waxen head nodded slowly. "But‑‑can you really change the past?"

Brek paused for a moment, solemnly. "We have all the power of the ship's converters," he said at last. "We have the high‑frequency achronic field, as a lever through which to apply it. Surely, with the millions of kilowatts to spend, we can stimulate a few cells in a schoolgirl's brain. We shall see."

His long, pale fingers moved swiftly over the control keys. At last, deliberately, he touched a green button. The converters whispered again through the silent ship. The achron‑integrators whirred again. Beyond, giant transformers began to whine.

And that still tableau came to sudden life.

Elora Ronee tore up the note that began, "Dear Bill‑‑" Brek and the Astrarch leaned forward, as her trembling fingers swiftly wrote: "Dear Tony‑‑I'm so sorry that I was angry. May I come with you to father's lecture? Tonight‑‑"

The image faded. "Minus four‑‑"

The metallic rasp of the speaker brought Brek Veronar to himself with a start. Could he have been dozing‑‑with contact just four minutes away? He shook himself. He had a queer, unpleasant feeling‑‑as if he had forgotten a nightmare dream in which the battle was fought and lost.

He rubbed his eyes, scanned the control board. The autosight was set, the pick‑ups were tuned, the director relays tested. His part was done. He tried to relax the puzzling tension in him.

"Minus three‑‑"

Sodium bombs filled the void ahead with vast silver plumes and streamers. Staring into the black cube of the screen, Brek found once more the six tiny black motes of Tony Grimm's ships. He couldn't help an uneasy shake of his head.

Was Tony mad? Why didn't he veer aside, delay the contact? Scattered in space, his ships could harry the Astrarchy's commerce, and interrupt bombardment of the Earth. But, in a head‑on battle, they were doomed.

Brek listened to the quiet hum of the achron‑integrators. Under these conditions, the new autosight gave an accuracy of fire of forty percent. Even if Tony's gunnery was perfect, the odds were still two to one against him.

"Minus two‑‑"

Two minutes! Brek looked down at the jeweled chronometer on his wrist. For a moment he had an odd feeling that the design was unfamiliar. Strange, when he had worn it for twenty years.

The dial blurred a little. He remembered the day that Tony and Elora gave it to him‑‑the day he left the university to come to Astrophon. It was too nice a gift. Neither of them had much money.

He wondered if Tony had ever guessed his love for Elora. Probably it was better that she had always declined his attentions. No shadow of jealousy had ever come over their friendship.

"Minus one‑‑"

This wouldn't do! Half angrily, Brek jerked his eyes back to the screen. Still, however, in the silvery sodium clouds, he saw the faces of Tony and Elora. Still he couldn't forget the oddly unfamiliar pressure of the chronometer on his wrist‑‑it was like the soft touch of Elora's fingers, when she had fastened it there.

Suddenly the black flecks in the screen were not targets any more. Brek caught a long gasping breath. After all, he was an Earthman. After twenty years in the Astrarch's generous pay, this timepiece was still his most precious possession.

His gray eyes narrowed grimly. Without the autosight, the Astrarch's fleet would be utterly blind in the sodium clouds. Given any sort of achronic range finder, Tony Grimm could wipe it out.

Brek's gaunt body trembled. Death, he knew, would be the sure penalty. In the battle or afterward‑‑it didn't matter. He knew that he would accept it without regret.

"Zero!"

The achron‑integrators were whirring busily, and the warrior Queen quivered to the first salvo of her guns. Then Brek's clenched fists came down on the carefully set keyboard. The autosight stopped humming. The guns ceased to fire.

Brek picked up the Astrarch's telephone. "I've stopped the autosight." His voice was quiet and low. "It is quite impossible to set it again in two minutes."

The telephone clicked and was dead.

The vessel shuddered and the lights went out. Sirens wailed. Air valves clanged. The lights came on, went off again. Presently, there were no more hits. Smothered in darkness, the great room remained very silent.

The tiny racing tick of the chronometer was the only sound.

After an eternal time, feeble emergency lights came on. The Astrarch came stumbling into the room, looking dazed and pale.

A group of spacemen followed him. Their stricken, angry faces made an odd contrast with their gay uniforms. Before their vengeful hatred, Brek felt cold and ill. But the Astrarch stopped their ominous advance.

"The Earthman has doomed himself as well," the shaken ruler told them. "There's not much more that you can do. And certainly no haste about it."

He left them muttering at the door and came slowly to Brek.

"Crushed," he whispered. "You destroyed me, Veronar." A trembling hand wiped at the pale waxen mask of his face. "Everything is lost. The Queen disabled. None of our ships able to undertake rescue. We'll be baked alive."

His hollow eyes stared dully at Brek. "In those two minutes, you destroyed the Astrarchy." His voice seemed merely tired, strangely without bitterness. "Just two minutes," he murmured wearily. "If time could be recaptured‑‑"

"Yes," Brek said, "I stopped the autosight." He lifted his gaunt shoulders defiantly, and met the menacing stares of the spacemen. "And they can do nothing about it?"

"Can you?" Hope flickered in the Astrarch's eyes.

"Once you told me, Veronar, that the past could be changed. Then I wouldn't listen. But now‑‑try anything you can. You might be able to save yourself from the unpleasantness that my men are planning."

Looking at the muttering men, Brek shook his head. "I was mistaken," he said deliberately. "I failed to take account of the two‑way nature of time. But the future, I see now, is as real as the past. Aside from the direction of entropy change and the flow of consciousness, future and past cannot be distinguished.

"The future determines the past, as much as the past does the future. It is possible to trace out the determiner factors, and even, with sufficient power, to cause a local deflection of the geodesics. But world lines are fixed in the future, as rigidly as in the past. However the factors are rearranged, the end result will always be the same."

The Astrarch's waxen face was ruthless. "Then, Veronar, you are doomed."

Slowly, Brek smiled. "Don't call me Veronar," he said softly. "I remembered, just in time, that I am William Webster, Earthman. You can kill me in any way you please. But the defeat of the Astrarchy and the new freedom of Earth are fixed in time‑‑forever."