Convergent Series (22 page)

Mandel was setting before she was finished. The modified beacon went back outside, into the ruddy light of Amaranth and the driving dust storm, and onto its little cairn of stones. Darya activated it, and nodded in satisfaction as the function light blinked to indicate that the beacon was working again.

She inched her way back into the waterfall cave, swathed herself completely in the quilt, and curled up on the ledge of rock. Stony lumps stuck into her side. The splashing fall provided a continuous spray of droplets and the noise of rushing water. Underneath that was the uneasy movement of Quake itself, groaning as the planet was stretched harder on the rack of tidal forces.

No one could expect to be able to sleep in such conditions. Darya nibbled on dry biscuits, closed her eyes, and fixed her mind on one thought:
she was fighting back
. What she had done was little enough, but it was all that she
could
do.

And tomorrow, she would find some new idea to save herself.

With that thought in her head and uneaten biscuits still in her hands, she drifted off into the most restful sleep since she had left Sentinel Gate.

Hans Rebka had another reason for wishing to be alone. Just before they had left Opal, another encrypted message had arrived from Phemus Circle headquarters. There had been no time to examine it in the haste of their departure, but while the capsule was descending the Umbilical toward Quake he had taken a first look. He had been able to decipher just enough to make him uncomfortable by the time they landed. As the aircar took him north away from Opalside and toward the starside of Quake, the message was burning a hole in his jacket pocket. He put the plane on autopilot, ignored the brooding scene below him, and set out in earnest to work on the message.

Headquarters had switched from prime numbers and cyclic ideals as the basis for their codes, to an invariant-embedding method. The messages were supposedly almost uncrackable—and vastly more difficult to read, even when you knew the key. Rebka appropriated most of the car's on-board computer power and began to grind out the message, symbol by symbol. It did not help at all that there were occasional data losses in transmission at the Bose Transitions, adding their own random garbling to the cipher.

The received signal contained three independent messages. The first, deciphered after three quarters of an hour of patient work, made him want to throw the whole facsimile record out of the car's window.

. . . THE ALLIANCE COUNCIL MEMBER WHO IS HEADING FOR DOBELLE USES THE NAME
JULIUS GRAVES
, OR APPARENTLY SOMETIMES
STEVEN GRAVES
. HE IS AUGMENTED WITH AN INTERIOR MNEMONIC TWIN, DESIGNED AS AN EXTENDED SUPPLEMENTARY MEMORY, BUT THAT UNION IS NOT FOLLOWING NORMAL PATTERNS. OUR ANALYSTS SUGGEST A POSSIBILITY OF INCOMPLETE INTEGRATION. THIS MAY LEAD TO VOLATILE OR INCONSISTENT BEHAVIOR. SHOULD GRAVES ARRIVE ON DOBELLE, AND SHOULD HE EXHIBIT BEHAVIORAL IRREGULARITIES, YOU WILL COMPENSATE FOR THESE TENDENCIES AND NEUTRALIZE ANY ILLOGICAL DECISIONS THAT HE MAY SEEK TO MAKE. PLEASE NOTE THAT A MEMBER OF THE COUNCIL HAS PERSONAL DECISION POWERS THAT EXCEED THOSE OF ANY PLANETARY GOVERNMENT CONTROLS. YOU MUST WORK WITHIN THIS CONSTRAINT . . .

"Thanks, guys." Rebka crumpled the message into a ball and threw it over his shoulder. "He's crazy and he can do anything he likes—but it's my job to control him and stop him. And if I don't, my head rolls! Just perfect."

It was another fine example of action at a distance, of government trying to control events a hundred light-years away. Rebka set to work on the next message.

That took another hour. It did not seem much use when he had it, but at least it provided information and did not ask for outright impossibilities.

. . . PERHAPS OF NO DIRECT RELEVANCE TO YOUR SITUATION, BUT THERE ARE WIDESPREAD AND INDEPENDENT REPORTS OF CHANGES IN BUILDER ARTIFACTS THROUGH THE WHOLE OF THE SPIRAL ARM. STRUCTURES THAT HAVE BEEN STABLE AND INVARIANT THROUGHOUT HUMAN AND CECROPIAN MEMORY AND IN ALL REMAINING ZARDALU RECORDS ARE EXHIBITING FUNCTIONAL ODDITIES AND MODIFIED PHYSICAL PROPERTIES. THIS IS ENCOURAGING MANY EXPLORATION TEAMS TO REEXAMINE THE POSSIBILITY OF PROBING THE UNKNOWN INTERIORS OF A NUMBER OF ARTIFACTS . . .

"Tell me about it!" Rebka glared at the computer that was displaying the offending transcript. "And don't you remember that I was all set to explore Paradox, before this idiot assignment? Before you dummies pulled me away!"

. . . WHILE PERFORMING YOUR OTHER DUTIES YOU SHOULD OBSERVE CLOSELY THE ARTIFACT OF THE DOBELLE SYSTEM KNOWN AS THE UMBILICAL, AND DETERMINE IF THERE HAVE BEEN SIGNIFICANT CHANGES IN ITS FUNCTION OR APPEARANCE. NONE HAVE SO FAR BEEN REPORTED . . .

Rebka turned to stare back the way he had come. The Umbilical was long since invisible. All he could see was a broken line on the planet's terminator, like a glowing string of orange beads on the curving horizon. A major eruption had begun there. He looked down to the surface over which he was flying—all quiet below—and skipped to the third message.

Which made up for the other two. It was the answer to Rebka's own query.

. . . A CECROPIAN ANSWERING YOUR DESCRIPTION. SHE IS INTERESTED IN LIFE-FORM EVOLUTION UNDER ENVIRONMENTAL PRESSURE, AS YOU SUGGEST, BUT SHE IS ALSO KNOWN AS A SPECIALIST IN BUILDER TECHNOLOGY . . .

. . . SHE GOES UNDER A VARIETY OF NAMES (AGTIN H'RIF, ARIOJ H'MINEA, ATVAT H'SIAR, AGHAR H'SIMI) AND CHANGES OF EXTERNAL APPEARANCE. SHE MAY BE RECOGNIZABLE BY AN ACCOMPANYING SLAVE INTERPRETER OF THE LO'TFIAN FAMILY. SHE IS DANGEROUS TO BOTH HUMANS AND CECROPIANS, RESPONSIBLE FOR AT LEAST TWELVE DEATHS OF KNOWN INTELLIGENCES AND TWENTY-SEVEN DEATHS OF PROBATED INTELLIGENCE.

ADDED NOTE: LOUIS NENDA (HUMAN, REPUTED AUGMENTATION), FROM KARELIA IN THE ZARDALU COMMUNION, IS ALSO HEADED FOR DOBELLE. HE IS ACCOMPANIED BY A HYMENOPT SLAVE. NO DETAILS ARE AVAILABLE, BUT THE KARELIA NET SUGGESTS THAT NENDA MAY ALSO BE DANGEROUS.

NEITHER THE CECROPIAN NOR THE KARELIAN SHOULD BE ADMITTED TO THE DOBELLE SYSTEM . . .

Rebka did not throw the printout from the car—it was moving too high and too fast for that. But he did crumple the message and toss it over his shoulder to join the other two. He had spent more than three hours deciphering those missives from Circle headquarters, and all they offered was bad news.

He lifted his head and stared out of the window ahead. Amaranth was behind him, and the car's roof shielded its light. He looked west, ready to catch the last gleam of Mandel-set before the primary was lost behind the dark crescent of Quake. The sun's rim dipped below the horizon.

His eyes adjusted. And as they did so they picked up a faint, blinking light flashing from a tiny red bead next to the control console. At the same moment an insistent beep started within the cabin.

Distress circuit.

The skin on the back of his neck prickled with anticipation. Sixty hours to Summertide. And someone or something, down on the looming dark surface of Quake ahead of him, was in big trouble.

The line of the beacon would bring him down on the fringes of the Thousand Lakes area, not far from the region Max Perry favored for the location of the Carmel twins. Rebka checked the car's power supply. It was ample—each aircar could make a trip right around Quake and still have something in reserve. No reason for worry there. He sent a brief message to Perry and Graves, then increased the car's speed and set his new course without waiting for either acknowledgment or approval.

Mandel was still hidden, but Gargantua was high in the sky and providing enough light to land by. Rebka stared ahead. He was skimming low over a chain of circular lakes, waters steaming and churning. Their turbulent surfaces matched his own mood. Nowhere, from horizon to bleak horizon, was there a sign of life. For that, he would have to look into the waters of the Thousand Lakes themselves, or in the deepest hollows of the Pentacline Depression. Or deeper yet—the most tenacious life-forms would burrow far under Quake's shifting surface. Would the Carmel twins have had the sense to do the same?

But maybe he was already too late. The twins were no specialists in harsh-environment survival, and every second the tidal forces at work on the planet below him grew bigger.

Rebka increased speed again, pushing the car to its limits. There was nothing else he could do. His mind wandered away into troubled speculation.

Gravity is the weakest force in nature. The strong interaction, the electromagnetic interaction, even the "weak" interaction that governs beta decay, are many orders of magnitude more powerful. Two electrons, one hundred light-years apart, repel each other with an electric force as great as the attractive gravitational force of two electrons half a millimeter apart.

But consider the gravitational
tidal
force. That is weaker yet. It is caused only by a
difference
of gravitational forces, the difference in the pull on one side of a body from the pull on the other. While gravity is governed by an inverse square law—twice the distance, a quarter the force—gravity tides are governed by an inverse
cube
law. Twice the distance, one
eighth
the force; thrice the distance, one twenty-seventh the force.

Gravity tides should be negligible.

But they are not. They grip a billion moons around the galaxy, forcing them to present the same face always to their master planets; tides worry endlessly at a world's interior, squeezing and pulling, releasing geological stresses and changing the figure of the planet with every tidal cycle; and they rip and rend any object that falls into a black hole, so that, no matter how strong the intruder may be, the tides will tear it down to its finest subatomic components.

For that inverse-cube distance relationship can easily be
inverted
: one half the distance, eight times the tidal force; one third the distance, twenty-seven times the tidal force; one tenth the distance . . .

At closest approach to Mandel, the Dobelle system was one eleventh of its mean distance from the primary. One thousand three hundred and thirty-one times the mean tidal force was exerted upon its components.

That was
Summertide
.

Hans Rebka had been told those basic facts by Max Perry, and he thought of them as he overflew the surface of Quake. Every four hours, the vast invisible hand of Mandel and Amaranth's gravity squeezed and pulled at Opal and Quake, trying to turn their near-spherical shapes into longer ellipsoids. And close to Summertide, tidal energy equivalent to a dozen full-scale nuclear wars was pumped into the system—not just
once
, but twice every Dobelle day.

Rebka had visited worlds where global nuclear war had recently taken place. Based on that experience he expected to see a planet whose whole surface was in turmoil, a seething chaos where the existence of life was impossible.

It was not happening. And he was baffled.

There were local eruptions—that was undeniable. But when he looked at the ground speeding beneath him, he could see nothing to match the scale of his imaginings.

What was wrong?

Rebka and Perry had overlooked a fact known since the time of Newton: gravity is a
body force
. No known material can shield against it; every particle, no matter where it may be in the universe, feels the gravitational force of every other particle.

And so, whereas nuclear war confines its fury to the atmosphere, oceans, and top few tens of meters of a planet's land surface, the tidal forces squeeze, pull, and twist every cubic centimeter of the world. They are
distributed
forces, felt from the top of the atmosphere to the innermost atom of the superheated, superpressured core.

Rebka examined the surface but saw little to suggest a coming Armageddon. His mistake was natural, and elementary. He should have been looking much deeper; and then he might have had his first inkling of the true nature of Summertide.

A wind of choking dust was screaming across the surface as the aircar came in to land. Rebka brought the car directly into that gale, relying on microwave sensors to warn of rocks big enough to cause trouble. The final landing was smooth enough, but there was an immediate problem. The search-and-rescue system told him that the distress beacon was right in front of him, less than thirty meters away. But the mass detector insisted that nothing the size of an aircar or a ship was closer than three hundred. Peering into the dust storm did not help. The world in front of the car ended with a veil of driving dust and sand, no more than a dozen paces beyond the car's nose.

Rebka checked the SAR system again. No doubt about the location of the beacon. He gauged its line and distance from the door of the car. He forced himself to sit down and wait for five minutes, listening to the sandstorm as it screamed and buffeted at the car and hoping that the wind would drop. It blew on, as strongly as ever. Visibility was certainly not improving. Finally he pulled on goggles, respirator, and heat-resistant clothing, and eased open the door. At least the combination was a familiar one. Howling wind, superheated atmosphere, foul-tasting and near-poisonous air—just like home. He had grappled with all that in his childhood on Teufel.

He stepped outside.

The wind-driven sand was unbelievable, so fine-grained that it could find a way through the most minute of gaps in the suit. It blasted and caught at his body. He could taste powdery talc on his lips in the first few seconds, somehow creeping in through the respirator. Millions of tiny, scrabbling fingers touched him and tugged at his suit, each one eager to pull him away. His spirits dropped. This was
worse
than Teufel. Without the shelter of a car, how could anyone survive such conditions for even an hour? It was a side of Quake that Perry, in his preoccupation with volcanoes and earthquakes, had not warned about. But given enough atmospheric disturbance, interior activity of a planet was not necessary to make it inhospitable to life. Blown sand that would allow a person to neither breathe nor escape would do the trick nicely.

Rebka made sure that he had a return line attached firmly to the body of the aircar, then leaned into the wind and crept forward. The beacon finally appeared when it was less than four meters in front of him. No wonder the mass sensors had not registered it! It was tiny—a stand-alone unit and the smallest one he had ever seen. It measured no more than thirty centimeters square and a few centimeters thick, with a stubby antenna sticking up from its center. The solid cairn of stones on which it nestled stood at the top of a small rise in the ground. Someone had taken the trouble to make sure that, weak as it was, the beacon would be heard over the maximum possible range.