Encounter with Tiber [v1.0]

by By Buzz Aldrin

  So we watched cable strain on readouts, and looked at what radar was showing us about how the sail folded in front of us, and spent a long, boring day before finally the ship was ballistic again and we were headed for our close approach to Zoiroy. It wasn’t till shortly before bedtime that Otuz muttered to me, “Did you notice Mejox?”

  “What about him?”

  “When have you ever seen him sit still for so much boredom?”

  “He has to sit still—his hand’s in a cast and his leg’s sore.”

  “You know what I mean. He didn’t make any trouble.”

  “I’d think you’d be glad.”

  “Oh, I am. And when I spied on the adults earlier this evening, they were all really happy about it, too. But it sure isn’t much like him. I suppose getting hurt and not being able to do anything about it must have made an impression on him.”

  Something about the incident did seem to change Mejox for the better. Certainly he became quieter and politer. I spent a lot of time coaching him on math, and within a day or two I felt that we were as good a pair of friends as ever.

  About fifty days later we were in final approach to Zoiroy. I don’t know what the others did, but I squeezed the button for anesthesia. Zoiroy was a much smaller star than the Sun, so it was only going to be eight gravities. We wouldn’t need support liquid in the lungs. Still, I had seen everything of close approaches that I wanted to see.

  By the time I was out of anesthesia, Captain Osepok had jettisoned the extra part of the sail that we would not need, maneuvered us onto the laser beam that we would ride for the next few years, and headed us out into the dark reaches of interstellar space. We had raced across our solar system, from the Sun to Zoiroy, in just sixty days—a distance that the first expedition to Kahrekeif, the one Kekox had been on, had taken two years, just under a thousand days, to cross.

  With the laser pushing us, we would reach the great cloud of cometoids which marked the outer boundary of our solar system in just about a year— and beyond them, then, we would voyage for more than twenty more years.

  I made a game of it to myself: going around the equator of Nisu was a long way—we had spent days doing it on the final tour. And Nisu’s orbit around Sosahy was forty times that far. And the distance from Nisu to the Sun was one hundred times as far as that. And the distance from the Sun to Zoiroy was about thirteen times as far as that, at the time we went. So we had already gone 52,000 times as far as it was around Nisu, and we had done it in only sixty days, and with the push from the laser beam we would eventually be moving at seven times our present speed . . .

  And it would still take twenty-three and one quarter years, nine eightdays, and three and two-fifths days, in all, from the moment of our launch until we entered orbit around Setepos, to get there. When I thought about how fast we were moving and yet how immense the distances were, I would end up staring out a viewport at the endless blackness between the stars, until one of the other children would sneak up on me and startle me. After a while I lost the habit of looking out viewports at all, or even of thinking of us as moving. Our world was our little metal torus, in the middle of a void dark, huge, and empty beyond imagining, chasing after a vast, dimly glowing disk.

  * * * *

  6

  A LONG TIME LATER, WHEN I HAD TOO MUCH TIME TO THINK ABOUT THE past, I would think of the first twenty years of the voyage, before any of us entered puberty and while things were still on the plan, as the “happy time.” I know it wasn’t perfect. I squabbled with the other children, and I remember many hurt feelings and apologies. Once I broke my wrist in the gym and had to wear a cast, and once Otuz got angry at Priekahm and beat her badly. There was a period of more than a year when Soikenn and Osepok would not speak to each other and none of us children knew why.

  But for all that, time went by pleasantly. Automatic machinery ran the ship’s functions, and it was so reliable that after the first few eightweeks, Captain Osepok visited the cockpit once per day only to make sure that things were functioning normally; years went by and nothing unusual ever happened. Every few eightdays, she would spend a couple of days practicing with the simulators, to keep her skills current, and now and again she would have me or Otuz practice the same maneuvers. Really, however, the controls were much simpler than they were for the lander simulations that we worked every few days, and steering and navigating the Wahkopem Zomos was much simpler than operating an ordinary aircraft.

  That left us a great deal of time to occupy, and with our immense library, including all sorts of visual and auditory recordings, we probably became the eight most educated people ever. We studied literature, music, history, dead languages, all the sciences, a dozen games of skill and strategy. We all worked out in the gym frequently.

  And of course there was an immense amount of research to be done. Though dozens of unmanned probes were passing through interstellar space ahead of us, they could only relay back what they had been programmed to report; if there was an interesting anomaly in the data, it took years for the data itself to reach Nisu, then more years for any radio message changing the program to get back to the probe. By that time, the probe, moving at half the speed of light or more, would be far away from the anomaly, so a new probe would have to be dispatched—in the hope that it could find the same spot in the vast reaches of empty space, and that the phenomenon would still be going on a decade or more later.

  But we were right there with our instruments. When any of the thousands of readings we took per second started to show something interesting, one or more of us could take additional observations; experiment with laser, radar, or particle beam probing; compare it with all the data up to the present—in short, we could really do science, interacting directly with our environment, in the way that people back home could not. That advantage, plus having so much time available, made us some of the most productive research scientists in history.

  Traditionally very good students are allowed to put their names on some scientific works in their last couple of years before puberty, but Otuz and I both had credits before we were ten, and more than a hundred each before we were twenty.

  But though we were understanding so much about where we were, and where we were going, it was getting harder and harder to understand news coming from home. We received the major broadcast channels over the relay continuously, along with any books and recordings we wanted, but somehow, Nisu and we seemed to be growing apart from each other.

  Part of it was the time lag caused by our increasing distance. After we had been four and a half years on the voyage, it took a full year from the time we sent the message to get a reply from Nisu. Twelve and a half years into the voyage, when we received word that the old emperor had died, it was two and a half years after the fact, and though Mejox endured the quarter-year of the selection period just as if it had been happening right then, the new empress had been on her throne for that same two-and-a-half-year radio lag by the time he knew her name. “It drives me crazy,” Mejox said to me once. “Somewhere back behind us, slowly catching up with us, is a radio signal that would tell me what I want to know. It’s so weird to know it’s already settled and there is no way at all that we can hear it any sooner.”

  “You could get out and wait for it,” Otuz said.

  He probably would have been just as glad if the message never reached us. The new empress was not a Roupox, and moreover she already had a child. Hence—though Mejox was by no means ruled out, since the council of the ruling families could choose anyone they wanted from within their own ranks—he was no longer nearly the candidate for emperor he had been.

  In the eighteenth year, as we reached peak velocity, we were about ninety percent of the way to Setepos, but it would take us a quarter of the total time to cover the last tenth of the voyage, for we were now moving at two-fifths of light speed and it would take us years to slow down safely. By now we children were old enough and experienced enough to participate in the deceleration maneuver, so Otuz was in th
e second seat in the cockpit, Priekahm watching instruments with Poiparesis in the observatory, and the rest of us working at terminals in the computer lab, making sure that the sail stayed straight and intact.

  The first part of the maneuver took the better part of a day, slowly furling the sail, taking in the diamond cable, tracking it to make sure it didn’t twist, tangle, or worst of all strike any other part of the sail or the ship, since the microscopically fine, spun diamond would slice through any other material. It was interesting, but it was also very much like all the practices we had been running for the past twenty-two eightdays.

  At last the screens showed that the great circle of the sail—which had been as big as Sosahy for so many years—filled the sky completely. A few glimpses of dark showed where, now and again over our eighteen years on the voyage, a particle as big as a snowflake had struck that vast sheet, instantly vaporizing a tiny part of it. Then, ever so slowly, that huge circle began to distort and fold in toward us. The last of the cable was winding onto the spool.

  The sail itself came in next, the rollers running smoothly to everyone’s relief. We had spent days checking all of them and making sure they were perfect, but a machine being used for the first time in eighteen years is not a comfortable thought no matter how careful you’ve been with it. There were anxious moments, now and then, as we cleared wrinkles, and though the collision alarm had sounded only six times since we started out—and none at all in the last five years—the thought kept crossing my mind that if we had to dodge sideways to avoid a stone smaller than my thumb, it might be an eightday before we straightened out the sail again.

  But the sail came in smoothly as well, and then we were ready for reaction maneuvering. The small rockets we used for positioning and maneuvering the Wahkopem Zomos were liquid hydrogen-antimatter, like the booster that had pushed us out of Nisu orbit. The silent flicker of their jets licked out from the ship in another display of auroras, but we had much less time to watch them. In less than a fifth of a day, we had moved out of the beam of the laser.

  Captain Osepok’s voice came over the intercom. “All right, everyone, get ready; this will probably feel very strange.”

  Years aboard the ship had accustomed us to the notion that outward toward the rim of the torus was “down,” inward toward the core cylinder was “up.” The acceleration from the laser acting on the sail was so small a fraction of the “gravity” from spin that we never noticed it.

  Then the tiny attitude-adjustment jets began to fire, and the whole ship swung slowly end over end, to face the opposite direction. It was disorienting, because we were so used to the ship’s centrifugal “gravity” never changing; the effect was small but felt subtly wrong.

  The jets cut out, letting the rotating torus act as a gyroscope to stabilize us in our new position. “Down” resumed its normality.

  “Position?” Osepok called into the intercom.

  A moment later we heard Priekahm’s voice. “It’s all correct. Attitude is accurate and we’re on trajectory. Nice work, Captain.”

  “You can thank Otuz. I just sat here and watched her drive.”

  We all looked a little startled, though my second thought after my initial surprise was, Well, why in the Creator’s name not? She’ll have to, eventually.

  Otuz spoke on the intercom. “Ready for sail deployment into magnetic configuration?”

  “Ready in the observatory,” Poiparesis replied.

  “Ready in the computer lab,” Kekox added, but then said, “But if our pilot will permit, since it’s going to take a third of a day, perhaps we could get some food and rest first?”

  “Good idea,” Otuz said, “pending approval of the captain—”

  We heard Osepok laughing. “Keep it up and anyone would think this was a real ship. All right, let’s take a couple of hours to eat and nap.”

  After the break, we deployed the brakeloop. Physically it seemed simple enough—a thread barely thick enough to be visible to the naked eye. We spent an eighth of a day paying it out, and a bit longer getting the spun-diamond shroudlines on which it was hung unwound.

  We couldn’t see the next step, and that was unnerving, but there was nothing to be done about it. To “see” it we would have needed a very high resolution electron microscope, even though it was happening along an immense distance.

  The “thread” was actually tightly coiled fibers much thinner than the naked eye could see. Once out in space, we gently applied a charge through the spun-diamond cables, which had been surface-doped with a conductor for the purpose. The thread began to repel itself, and the coils pushed open; shortly, it had formed an immense loop behind us, bigger in circumference than the East Island back on Nisu. As the charge was applied we had begun to spin the ship back up to rotational speed, so that in short order there was gravity again.

  Now we bled off the charge from the loop; centrifugal force would hold it open. Slowly Otuz and Osepok applied a current through two of the conducting shrouds.

  Like the spun-diamond shrouds or the light sail, the braking loop was effectively one immense molecule, in the shape of a tube formed into that immense ring. Within the tube was a microscopic ribbon of a super-conductor—or rather of a material that when cooled enough would become superconductive. The tube itself, when a mild current was applied, became cold on the inside and hot on the outside, carrying away heat to maintain superconductivity. Otuz watched in the cockpit as the temperature of the loop fell steadily until it was well within the range for superconductivity.

  Now that the thin inner ribbon was superconductive, we began to apply current to it, so that shortly an electric current was flowing through that infinitesimally thin wire around that huge distance.

  “Watch your viewport for a show,” Osepok said.

  There was a low thrumming through the body of the ship. All the long eighteen years of the outward voyage, we had been capturing a very small portion of the laser energy to drive antimatter converters; now the antimatter we had saved up, so little of it that if you could make it into a lump it would balance on a fingertip, would provide power for most of the rest of the journey.

  And it wasn’t just the ship’s life-support and electric systems that needed energy. In the central cylinder, well away from us and in a sealed, insulated space, there was a great generator. It was the vibration from that which we now felt through our feet as the generator built up that huge current in the loop.

  Across the next twentieth of a day, we felt the brakeloop begin to drag us, and our weight moved a little away from the “floor” we had been used to, toward what had been the “rear window” and now was the front of the ship. Interstellar space is a hard vacuum, better than any that can be made in a laboratory, but not an absolute one. There are about 50,000 atoms of hydrogen in a body-volume of space, which sounds like a lot until you remember that there are about 500,000,000,000,000,000,000,000,000 atoms in a body-volume of ordinary air. When the loop swept through that thin hydrogen, carrying such an immense current at our tremendous velocity, it simply tore those hydrogen atoms apart, even at immense distances from the loop itself. A current flowing through a conductor produces a magnetic field, and the bigger the current, the stronger the field. A magnetic field exerts a force on a charged particle; the direction of the force depends on the charge on the particle. Since a hydrogen atom is made up of a single electron (with a -1 charge) orbiting a single proton (with a +1 charge), the magnetic field of the loop would literally tear the atoms in its path apart, pushing the electron one way, and proton the other.

  But to change the motion of anything requires energy; separating the electron and proton took some energy, and then as the charged particles were whipped around in the magnetic field, they absorbed yet more energy. And the source of that energy was the motion of the loop. As the kinetic energy of the loop became the thermal energy of the thin interstellar gas, the loop slowed down, and since we were tied to it, so did we. Or look at it this way—every push or pull the loop exert
ed on a charged particle had to be matched, by the laws of motion, with an equal and opposite push or pull on the loop, and the sum of all those tiny forces, added up across the immense length of the loop, was a force big enough to slow us.

  “Now that we’re running normally,” Poiparesis said over the intercom, “let me show you something on the screen.”

  Behind us, a deep blue, almost violet, glow blazed in a huge ring. “What—” I asked, not quite able to form the question.

  “Braking photons,” Soikenn said. “The same thing we see in a cyclotron. When you accelerate a charged particle it gives off photons—that’s why electricity running through a coil creates a magnetic field, because photons are the carriers of magnetism, among other things. And in this case what you’re seeing is all those protons and electrons changing direction and speed within a tiny fraction of a second. That’s a lot of acceleration, and they’re giving off a lot of fairly high-energy photons, high enough energy to be visible light and ultraviolet.”