Starquake

by Robert L. Forward

  Another picture flashed on the screen. It was the carcass of one of the aliens, surrounded by hundreds of tiny carcasses. All had obviously been seared by a super-hot flash of hard gamma rays from the infall of a large chunk of matter onto the star. "It seems that being the one chosen to herd in the food supply can be dangerous. I think that one of the ways we can help these aliens is to keep a watch on the larger incoming chunks and warn them away from the mountains during the time they are falling. That should cut their gathering losses. Also, we might be able to stabilize the amount of infall so they have a constant supply of food. Once we have secured their food supply, then maybe they will have the leisure time to talk to us and develop their culture."

  Three turns later, it was time for the expedition to leave. Star-Glider and Far-Ranger said goodbye to Lieutenant Star-Finder, then watched as the interstellar exploration ark, Amalita Shakhashiri Drake, pulled a few meters away for safety. They couldn't feel the humming as the spinor warp drive on the ark was activated, but they could see a segment of the black, starry sky start to warp as the space between Dragon's Egg and a point some 100 light-years away was nullified. A large red marker star zoomed in from the distance, so close they could see the cloudy patches on it. Then the spinor drive reinserted the nullified space, but this time on the other side of the ark. The Amalita and the red star zoomed back into the heavens together.

  "A hundred light-years in the time it takes to move a single tread length," said Star-Glider.

  "All you need to do is shrink the hundred light-years until it is but a tread-length long," Far-Ranger said. "Bright's Oath, my pouch is dry. How about some juice before turnfeast?"

  "Good idea," Star-Glider said. "I have a few bags of West Pole Double-Distilled in my locker at my quarters."

  "Great!" she said, her nearest eye giving him a long, slow, wink. "You spread the field lines and I'll follow along behind."

  He lead the way to his cabin, the moving bulk of his conducting body spreading the weak magnetic field lines stringing through the space-station plates. They were nowhere near as strong as the trillion-gauss fields on Egg so there was no need for him to act as pathbreaker, but he didn't mind having her snuggled up to his trailing edge. As they moved down the roofless corridor, a few of his eyes looked up into the sky to watch the formation of six asteroids pass over once again. Around each glowing mass were tiny specks that glared periodically. They were the herder rockets that kept the condensed asteroids in their proper position around Dragon Slayer. If these ever failed, the humans would be torn apart by the ferocious tides of Egg. He suddenly stopped and all his eyes turned upward.

  "What is the matter?" Far-Ranger asked.

  'The pattern is wrong," Star-Glider replied. "The pulses are coming at the wrong times. Something has happened to the Eyes of Bright!" For a blink he panicked at the thought of those large objects falling down on him. Then reason reminded him they were in orbit. They wouldn't fall, but something was definitely wrong. He flowed around Far-Ranger and headed back up the corridor to the command deck at full tread-ripple.

  "The humans are in trouble!" he said. "Follow me!"

  Danger

  06:50:06 GMT TUESDAY 21 JUNE 2050

  Outside Dragon Slayer, the six dense compensator masses circled, nudged this way and that by the powerful herder rockets. The rockets could not be allowed to get too close to the destructive tides of the ultra-dense masses, so each rocket pushed at a distance using the magnetic fields generated by a collection of magnetic monopoles in its bulbous nose. As each compensator mass reached one side of the ring, a yellow flare of a jet could be seen from a herder rocket, adjusting the orbit of the mass to keep it in its proper path. As the compensator mass came around to the other side of the ring, the opposite herder rocket would fire, pushing the dense asteroid back the other way. The scene repeated thirty times each second, once every two dothturns to the watchers on Egg below.

  A jet on one of the herder rockets faltered as a meteorite tore through the fuel feed section, taking out two of the three triply-redundant fuel valves and damaging the third. A fifth of a second later the jet functioned correctly, but the next time it sputtered once again. The compensator mass that the herder rocket was supposed to control started to wander out of its place in the ring. Soon all the masses were wavering slightly as their rockets tried to maintain some semblance of order.

  "Emergency!!" Dragon Slayer's computer sounded the alarm through the loudspeakers. "A meteorite has damaged one of the herder rockets!"

  Amalita was returning from checking the upper tank when the strong gravity tides of the neutron star grabbed her and

  pulled her back down the passageway where she collided with Jean, who was putting on her suit. Thenext fraction of a second the two women were separated and jerked toward the outer wall of their spherical spacecraft.

  Amalita grabbed a stanchion and held on. "What's the matter?" she yelled at Pierre. Pierre cinched up the belt on his console chair and activated his console.

  "A rocket has malfunctioned," he said.

  Jean, floating free near Pierre, was slammed again into the outer wall, then flew inward toward the center of the ship, where she held onto the back of a chair. The next part of the cycle her legs were pulled outward again as if she were on a rapidly spinning merry-go-round.

  "Can you fix it?" Pierre asked the computer.

  "No. The stress crack in the remaining fuel valve is growing," the computer reported. "You have a maximum of five minutes."

  "We'll be torn apart by the tides," Jean screamed as the forces pushed and pulled on her body. They became stronger, ripped her from her precarious handhold and slammed her unconscious against the outer wall. At the next cycle, her limp body came flying inward again.

  "Got her!" said Amalita, moving quickly from one handhold to another in the lulls between the forces.

  "Put her in an acceleration tank!" Pierre hollered. Meanwhile, Doc Wong had made his way around the central column and helped Amalita open one of the circular hatches in the wall. They stuffed Jean into the spherical tank. Jean roused a little as they were putting her in, and Doc managed to get her mask on before they shut the door.

  "Air OK?" Doc hollered over the intercom. The figure inside gave a dazed nod, and Doc noted her chest expand in a deep breath. He activated the tank and water droplets splashed over the portholes as the soothing liquid covered the bruised body.

  The cheela communication console lit up. The robotic cheela, Sky-Teacher, was back on the screen. Flitting about him in the background, blurred images of live cheela were busily responding to the catastrophe.

  "A rocket is failing," Sky-Teacher said. "Are you in danger?"

  Pierre spoke quickly to the robotic image as the gravitational forces jerked him about in his harness.

  "We've had it," he said. "I'm afraid you'll have to retransmit that last HoloMem directly to St. George.... Goodbye."

  Pierre noticed a hesitation in Sky-Teacher's response and stopped. He could see a clustering of live cheela bodies to one side of the robot. The eyes and tendrils on that side of the robotic body accelerated into a blur as Sky-Teacher talked to the live cheela at near-normal cheela speeds. A fraction of a second later, the hesitation in Sky-Teacher's eye wave pattern was replaced by its normal rhythm.

  "WAIT!" Sky-Teacher cried. "We will rescue you!"

  "In five minutes?" Pierre shook his head. "Impossible!" Timing the gravity strains, he dove down to the library console to change the rate for data transfer to emergency mode.

  06:51:05 TUESDAY 21 JUNE 2050

  The young post-doctoral student swayed back and forth as the senior engineer put the final touches on the machine. Although he had gotten his doctorate in tempology and was not a bad engineer himself, Time-Circle knew that making a magnetized and electrified black hole this big was not something to be left to mere scientists. Fortunately, his grant from the Basic Science Foundation had been large enough so he could afford to hire the best engineer on Egg, Cli
ff-Web.

  Engineer Cliff-Web was not afraid to take on "impossible" projects. After stretching his tread as Assistant to the Chief Engineer on one of the first jump loops, he had taken on the design of the first space fountain. Cliff-Web had designed a tower 200 times taller than the diameter of Egg, and not only showed how to build it, but proved that it would make money if it were built. He sold the idea, formed the team, and then went on to other "impossible" engineering projects. Time-Circle had been lucky to have gotten Cliff-Web for his project. But then, he doubted that any other project could have been more challenging and more "impossible" than this one— building a time machine.

  It had been almost two human minutes since the time machine project had started. For his doctoral thesis, Time-Circle had proven the feasibility of time travel by sending signals through time. As a result, he had received his Doctorate of Tempology and had been allowed to choose a new name for himself.

  His first time machine had only two time communication channels. He had modified a normal black-hole generator so that it used a mixture of protons and magnetic monopoles with high speed and high relative angular momentum. By making the black hole out of both magnetically and electrically charged matter, he had been able to make the rapidly spinning prolate mass open up its event horizon at spin speeds less than 99% of the speed of light. The resultant black hole lasted less than a sethturn, but by careful timing, Time-Circle had sent a gamma-ray pulse forward in time through one channel and backward in time through another channel before the black hole popped into a tiny blast of radiation.

  The Time-Comm machine Engineer Cliff-Web was now building for him would be permanent and could send signals backward or forward to any time where the machine was in existence or until all eight communication channels were filled with messages. It would be a long time before anyone, even the rapidly advancing cheela, could make a time machine that allowed physical travel of living beings, but even a time-traveling message machine like Time-Comm could be useful.

  Now, it was finally completed. The construction crew had been sent off to their personal compounds for a well deserved rest, while their robot partners were being reprogrammed for their next job as part of Cliff-Web's growing construction empire. Cliff-Web remained to check out the device and make the final adjustments.

  Finally satisfied with the results, Cliff-Web slid to one side of the combined touch-and-taste screen.

  "It works," he muttered quietly.

  "Good," said Time-Circle. "Let me check it out. Hmmm. This is an historic moment, what message shall I use? It has to be short, but it should be significant. I've got it!" His tread moved over the screen as he set up the message.

  "Turn back O Time," Cliff-Web muttered.... "I read it on the detection screen just as I tweaked the last parameter."

  'That is what I just sent!" said Time-Circle. "It works! It works!"

  "I already said that," Cliff-Web reminded him as he pouched his tools and measuring instruments. The gravity wave detector was long and massive, but folded up into a package that fitted nicely into the big pouch in his body that he had developed for

  instrument transport. At the very last he went over to the corner and picked up the plant that had been sitting there. It was his trademark, pet, and closest companion—a cleft-wort plant. Checking the plant over carefully, Cliff-Web put it into another pouch in his cavernous body.

  "You've plugged up the past of one of your four back-time channels," he warned as he left.

  Time-Circle wasn't listening. He was preparing a message to himself at the dedication ceremonies for the Time-Comm machine some three turns into the future. As he was sending it, a confirmation message came from his future self.

  He had arranged for it to use the same back-time channel that he had used for his test message. His future self reported that the message had been received at the dedication ceremony, and only two sethturns early. The wave pattern of Time-Circle's eye-stubs slowed as he made adjustments to the time-interval circuits. The message utilization code tacked onto the end of the confirmation message indicated that the message was within a few bits of the maximum that could be sent over that distance in time. Time-Circle had the computer make a scroll copy of the coded message so he could later calculate the exact bit-time product, but it looked as if it were close to what his theory had predicted—864 bit-greats. That meant that he could send a message 864 bits long over a time interval of one great of turns, or a one-bit message over 864 greats. Time quantization statistics would cause variations, of course, and one of his research tasks with the machine was to determine those statistical variations.

  He didn't want to fill up any more channels with messages until he had done some calculations, so he put a password lock on the touch-and-taste screen, which turned a blank silver patch in the yellow-white floor as he headed for the door.

  The walls around the Time-Comm laboratory were extra high, and thus very thick at the base. As his tread approached the door, a sensor pattern in the floor read the wrinkles in his tread and the inner door slid open. He entered the security port in the base of the wall and felt his body stiffen as a magnetic field penetrated his body and generated a magnetic susceptibility map to compare with the stored version.

  "You are carrying a scroll out that you did not have when

  you came in," a mechanical sounding voice vibrated through his tread.

  "It's the instruction manual for the operation of the Time-Comm machine," Time-Circle explained. "I'm going to read it at home."

  "Accepted," replied the machine. The magnetic field disappeared, and the outer door opened. Before Time-Circle left, he set the intruder barriers. He couldn't see the barriers, but the top of the tall wall now bristled with alternating north and south magnetic poles. The fields were so strong and the gradients so high that it would take forever to push anything through them to get over the wall. The field strength near the center of the barrier was strong enough to elongate the cells in a living organism until they didn't function properly. He had been told it felt as if you were putting a tendril into the purple-hot flame of a gamma-ray flare. He noticed the fading track of Cliff-Web that indicated he had pushed off down the slanting corridors to the north-east. Time-Circle moved in the opposite direction and headed Bright-west for the Administrative Compound of the Inner Eye Institute to arrange for the dedication ceremonies.

  Cliff-Web felt quietly pleased with himself. First the Space Fountain (he could see the tiny spike of light growing up into the sky over the wall at the end of the long north-east corridor), now the Time-Comm machine. The time machine was finished so far ahead of schedule that the formal turn-on ceremonies were still scheduled for three turns from now. He wasn't sure whether he would bother going to them. He hated to have people tell him how wonderful he was. It made his eye-stubs squirm just thinking about it. He was anxious to get home to his holovid and his plants. He then remembered his cleft-wort that he had pouched when he left. He stopped and, forming a manipulator, reached into his pouch and pulled out the plant.

  "There, there, Pretty-Web," he said. "You getting too warm?" He held the plant up to his eyes and looked it over carefully. It was too warm. It was almost the same yellow-white on the top as it was on the bottom, and it was drooping a little between the acute angle of the artificial cleft that took the place of the natural rock clefts in the mountains where the cleft-wort normally grew.

  Now that the plant was out in the open where it could see

  the dark blackness of the starry sky, the top surface cooled off and turned a velvety red-black, while the underside turned a reflective silver. Cliff-Web lifted the plant up to his own deep red topside and put the base of the holder into a pouch he formed on his topside. He directed his body to heat the pouch; and the plant, with its roots in a source of heat and its topside cooled by the black sky, started to regain its normal circulation and perked up. The tension threads that wove back and forth from one side of the cleft to the other tightened, and the topside corrugations gr
ew more wrinkled, increasing the emissivity of the top surface. Tiny threads of red light started at random in the black-red top, and wended their way down the feeder veins to the dull red stem leading to the yellow-white base. It was a pretty moving display. Cliff-Web could almost feel the hum of the plant as it worked to make food.

  Relaxed and happy with himself and his plant, Cliff-Web didn't hurry as he pushed his way north-east. Using the walls of the compounds along the street as a levering wedge, he pushed his body through the magnetic field lines that tried to prevent his northward motion.

  For a while he moved through the slumlike area of Old Town that surrounded the sprawling grounds of the Inner Eye Institute. Most of the compounds here had their window slides closed, so there wasn't much to see except wall. The intersections were irregular and he found he had gone too far east before he realized he should have taken a north-west tack back a few intersections. The north-west street he had available now was 60 degrees north of east instead of the nominal 30 degrees. Grunting with annoyance at himself, he pushed his way across the intersection, found the south wall of the street and pushed north-west, this time more north than west. A robotic glide-car for hire passed in the sparse traffic and he was tempted to wave it down, but it was going in the wrong direction, and besides, he could use the exercise.

  As Old Town changed to the suburbs of Bright's Heaven, the street pattern became more regular. The main thoroughfares ran straight east and west, with the side-pairs of streets angled off at exactly 30 degrees north from east in crisscrossing patterns that formed diamond and triangular blocks. The personal compounds were built right up to the walkway, and the walls had been coated with frictionless tile to allow for rapid motion