The Depths of Time

by Roger MacBride Allen

  She cleared her main board and brought up the symbol-logic displays for the destroyed intruder’s trajectory, the intruder she had found, and the one the weapons team had found. She studied the three, looking for relationships and patterns that might lead her to the other three that were still unaccounted for. She added her arrival projections, and the pre sensor-blinding tracks as well. The big screen was a tangle of traces and vectors, dots and lines, color-coded sym-log gibberish.

  But Sayad could read it all. The incomprehensible mishmash made perfect sense to her. The pattern was clear. Whoever had sent these probes through the wormhole had set up pseudorandom evasive patterns that ended with the surviving intruders in a radial-symmetric dispersal pattern, each craft heading off in a different direction. She frowned, and thought fast.

  Thirty-two attackers to begin with, but half of them diversionary. Sixteen actually attempted to get through the wormhole, but the Standfast had taken out ten of them, and Upholder had killed one. She had good current realtime tracks on two of the survivors, and she had no doubt the weapons team would take them out in short order. That left her with three intruders for which she had no reliable current track. She had lost them in their evasive-maneuver phase, thanks to that sensor-blinding explosion of Upholder’s kill. Think. Six intruders. Three accounted for. Three missing. Six out of sixteen intruders programmed to go through the wormhole and disperse. She worked her board controls, slicing up the sphere of space around the wormhole into sixteen pyramid-shaped sectors, the points of the pyramids meeting at the center, at the worm-hole.

  The geometry required mostly six-sided and some five-sided pyramids to allow an absolutely precise fit, but she ignored that level of nicety for the moment. She threw the tracks of the detected intruder up into her improvised radial-sector map, and was not in the least surprised to see it was easy to match them up with the centerlines of three of the sectors. Each of the known intruders was moving on a direct radial course out from the wormhole, each moving more or less precisely down the center of its assigned “slice” of space. It was so tidy, so accurate, that Sayad had not the slightest doubt that the remaining three intruders would likewise be found in the centerlines of their sectors.

  That was a mistake on the part of whoever had programmed the intruders, and a big one. It meant she only had to search near the centerlines of the remaining sectors, thus eliminating about 99 percent of her search area.

  Well, if the person who had programmed the intruders loved order so much as to be tempted into one mistake by it, maybe he or she had made another.

  She had tracks for those three, but they were more than a minute old, closer to ninety seconds by now: far too old to be of any direct use. But they at least told her the arrival order for all six of the intruders that had gotten past the Standfast. She compared it against the known intruders’ sector assignments.

  And there it was. Breathtaking. Perfect. Tidy. And incredibly stupid. The intruders had been slotted into their sectors in order of their arrival, rather than at random. All she had to do was figure out where in the arrival sequence an intruder had been—something she could derive easily enough by noting the moment of each arrival—and she would know just about where to look along the lengths of the centerlines of three particular sectors of space, to find the missing intruders.

  Her fingers danced over the controls. She focused the long-range detectors at the appropriate points in space— and was rewarded with almost immediate detection returns on three bogies.

  “If that’s not black magic I don’t know what is,” Koffield said from behind her. “Brilliant work, Sayad. Later you can tell me how you did it.”

  Sayad smiled at her board. “Yes, sir,” she agreed as she routed the detection tracks to weapons. “I’ll be glad to oblige.” Later. Now there was far too much to do. The three new intruder tracks were on the far side of the wormhole from the Upholder, and doing their damnedest to get still farther away with every moment that passed. The Upholder was going to have a devil of a time pursuing any one of them, let alone pursuing, intercepting, and destroying all three. They would need smart tactics, and need them fast, to have any hope of blasting them all. She set to work gathering information, coaxing more data out of the pinpricks of light that were doing their best to escape.

  A flare of light lit up the main screens, and Sayad was focused enough on her own work, she did not know at first what it was. Ah, of course. Fire control had locked in and blown out their second bogie. Sayad checked her displays. It was, not surprisingly, the one the weapons team had found for themselves. That left the one she had first spotted, the one bearing straight down on them. And fire control was already redirecting fire toward intruder three. She let them do their job while she did hers, and concentrated on intruders four, five, and six. The flare of the explosion had blinded her detection systems again, but this time it didn’t matter. Bogies four to six weren’t trying anything fancier than flying in a straight line.

  And then, one after another, bogies one, two, and three each did something very fancy indeed. They started accelerating, putting on speed—and putting it on with a vengeance.

  Sayad frowned and checked her displays. The numbers they were showing were impossible. Accelerating was too mild a word for what those ships were doing. They were doing hundreds, no, thousands of gees in acceleration. Even as she watched, the acceleration displays for each of them went off-scale high. No ship, not even an unpiloted ship, could possibly survive the thrust levels those ships were putting out, no matter what kind of acceleration buffers they had aboard.

  And there, as she watched, one, two, three, the three bogies just—vanished. Gone. Did not show on any of her instruments. Her velocity meters showed why, and it was impossible to believe them. Light-speed. The damned intruders had accelerated all the way up to light-speed in the space of a few seconds.

  And nothing, nowhere, could possibly travel at light-speed. That was an article of faith, an unalterable fact. That was the whole reason for the existence of the time-shaft wormholes—to serve as a creaky, awkward, difficult substitute for true light-speed and translight-speed travel. If you could go faster than light, you didn’t need the wormholes.

  So why in the name of the devil’s chaos had the intruders just used a wormhole? And how did they jump to light-speed? And where the hell were they going? And what the hell was the Upholder going to do to stop them?

  But then her attention refocused itself on the problem still at hand, the problem Upholder could still do something about. That one remaining intruder, the one just coming into range. She flipped back through all her data, through all her guess-upon-guess-upon-guess extrapolations. If she had it right, the one coming up on them right then was not only the last of the surviving six to come through the worm-hole, but was to have been the last of the sixteen in the intended schedule. Whatever the first ones out of the chute had done was what this one was about to do—

  She slapped a hand down on the comm key. “Weapons! Remaining target is about to commence massive acceleration and blow right past us. Advise you fire scattershot railgun rounds across its projected course! Fire now, now, now!”

  If fire control was fast enough off the mark, they should at least be able to hit this one as it started its escape run. There was a faint whir-thump, whir-thump, whir-thump from somewhere belowdecks, a sound and vibration so slight she wouldn’t even have noticed it if she hadn’t been waiting for it. The railgun was firing. Sayad watched her screens and the projected course of the intruder, and the cloud of scattershot pellets expanding out from their dispersal point. They were no more than tiny balls of perfectly ordinary iron, but if fire control had done its job right, the intruder was going to pass through a cloud of several thousand such bits of iron at a minimum closing rate of ten or fifteen kilometers a second. And if the intruder started its acceleration run before it hit the cloud— well, the faster it flew, the harder it would hit.

  Koffield leaned in over her and hit the comm button hi
mself. “Captain to conn! Attitude X-125, Y-010, Z-220, full emergency thrust! Immediate action! Fire control! Saturation fire of scattershot across intruder’s projected course! All hands! Impact and hull breach alert!”

  The Upholder lurched crazily about on her long axis and fired her main engines. Sayad stared wide-eyed at her screens. She hadn’t seen it. Thank the stars Captain Koffield had. If the intruder hit the scattershot and blew up, it would likely do so a mere five or six hundred kilometers from the Upholder’s present position. And when a target that big hit a cloud of scattershot at high velocity, it would fill all of surrounding space with shrapnel. The ship needed to get out of there, and fast.

  The acceleration compensators bucked and shuddered as they struggled to correct for the sudden shifts in velocity. The whole ship creaked and moaned as her structure took up the acceleration.

  “Defense systems!” the captain shouted. “Current status! How long can you hold a maximum electromag shield around the ship?” Most of the crew regarded the ship shields as more nuisance than protection. They sucked in inordinate amounts of power, jammed or degraded every detection system on board, and tended to scramble computer circuits that weren’t shielded with absolute perfection. Worst of all, it was impossible to fire the engines with the shields up. But if the Upholder was going to be practically next door to a bomb that was about to go off, Sayad was ready to put up with any degree of nuisance.

  “Ah, ah, estimate thirty seconds, sir,” a nervous voice replied. Sheelton, it sounded like. “Twenty-five seconds with aft-enhanced deflection.” Aft-enhanced shields would protect the whole ship, but focus a larger fraction of that protection across the aft section, which was going to take the brunt of the impacts with the ship in its present attitude.

  “Very well.” Koffield paused for something less than a heartbeat, then issued his orders. “Rig for aft-enhanced deflection, maximum power, and stand by to activate on my command. Conn, prepare for emergency engine shutdown at my command. Advise me the moment engines are safed. Once that thing blows, we’ll kill the engines, light the shields, and hang on. All hands, rig now for impact, collision, and hull breach condition one. I say again rig now for impact, collision, hull breach condition one.” He shut off the intercom.

  Hatches slammed shut, sunshields swung shut over viewports, alarms hooted. Rigging for hull breach condition one meant all hands not in pressure suits and not standing watch were supposed to dive for their suits and get into them—but everyone on the bridge was, of course, standing watch. None of them could be spared from their duties for the sixty to ninety seconds it would take to pop the suits from their lockers and get them on. No one on the bridge moved toward the suit lockers, but Sayad was far from the only one who glanced at the closest locker and did a quick mental rehearsal of the steps needed to get her suit on.

  Condition one rules said the captain could suit up or not at his own discretion. And it would be easy to argue that a suited-up captain would be better able to maintain effective command during a hull breach. But of course, morale might be a problem on a bridge where the only one going for his suit was the captain.

  Koffield made no move toward the suit lockers. As best Sayad could see, he did not so much as glance in their direction. She watched her screens for what she knew was going to happen—and felt her heart start slamming against her chest when it did. “Sir!” she called out. “Remaining intruder commencing acceleration run! No course change or attempt at evasive action. Intruder on collision course with scattershot.”

  “Time to impact?”

  Sayad shook her head. “Velocity ramping up too fast for solid numbers. Estimate impact on scattershot in thirty to forty seconds.”

  “Damn it!” Koffield slammed his fist against the console. “We’re nowhere near clear.”

  One glance at her screens had told Sayad that much. The Upholder would be well under a thousand kilometers distance away from the point of impact.

  Koffield checked her displays. “No time to figure the rates and ranges,” he said, half to himself and half to her. “We’re going to have to do this one by feel.” He flipped the switch on the intercom again. “This is the captain. Conn, you will perform an all-engines emergency throttle-down to zero power and safing when I call Mark One. Understood?”

  “Orders received and understood, sir,” a voice from conn replied.

  “Defense systems. Activate maximum shields, aft-enhanced deflection, five seconds after I call Mark One, or five seconds after you see all engines stop or safe, or when you hear me call Mark Two. Whichever of those happens, activate shields. Repeat and confirm.”

  “Um, ah, yes, sir.” Definitely Sheelton. Sayad could hear him forcing himself to get calm, get professional. “Go to, ah, full-surround shields, max aft-enhanced, at first of any three events: call of Mark One plus five, or engine stop plus five, or call of Mark Two. Received and understood.”

  Sayad understood the point of the complicated order. The impact was going to be almost unimaginably violent. With that much energy blasting out so close by, lots of things could easily go wrong. This way, if the intercom blew, or the repeater displays went out, or Koffield was killed before he could give the order, the shields would still come up. She was glad Koffield had ordered repeat and confirm. They all needed Sheelton to get this one right.

  “Very good, defense systems. All hands, stand by. Any impact estimate update, Sayad?”

  “Estimate still holds. Now ten to fifteen.”

  “Conn, defense systems,” Koffield called out. “Stand by for my commands. Let’s get this one right, ladies and gentlemen.”

  Koffield leaned in close, his face next to hers, and stared hard at the displays, watching the numbers change, the projections adjust, the variables shift. If he called his commands too soon, they would lose priceless seconds of escape acceleration time, and the electromagnetic shields might fail before the blast wave had expanded out past the ship. Call them too late, and the radiation and blast debris could catch them with the shields not yet activated and up to power.

  “Verbal time in seconds to and past first estimate,” he ordered, not taking his eyes off the patch of screen that showed the visible estimate.

  “Impact first possible in eleven seconds,” Sayad said “Ten. Nine. Eight. Seven. Six. Fiver—It’ll take more than five seconds for the engines to stop and the shields to come on, she thought. He’s gambling on a late impact. She kept up the count, keeping her voice steady, calm. Just say the words. “Four. Three. Two. One—”

  “Conn, Mark One, all engines emergency stop and safe! Now, now, now!”

  But the engines were dying before he was even done speaking the word Mark, the ship’s frame shuddering and vibrating anew as the stresses rearranged themselves.

  “Zero. Impact now possible. Plus one second. Two. Three. Four. Five.”

  “Engines all stopped and safed!” came the call from the conn.

  “Defense systems—Mark Two! Mark Two! Shield full, max aft, now, now, now!”

  And the lights dimmed and throbbed as the shields grabbed greedily at all the ship’s power they could take. Sayad’s screens flickered and distorted for a moment as the electromagnetic shielding pulsed up. Then her displays cleared, steadied. Sayad tried to hold herself steady as well. “Six,” she intoned. Steady. Professional. “Seven. Impact detected.”

  But she didn’t need to say that, no, not at all. A flare of light bloomed out in the darkness, blinding the Upholder’s sensors once again.

  “Shields at seventy percent. Eighty. Ninety. Ninety-five. Ninety-eight. Stability flicker.”

  “Hold at stable point!” Koffield called. The lights dimmed again, and the ship’s fabric moaned and creaked as the shields took hold, wrapping a thick, clumsy wall of electromagnetic energy around her.

  “Dropping to stable point. Holding at ninety-seven-point-five. “

  “Hang on!” someone on the bridge shouted needlessly. No one in the compartment was giving any thought at all to an
ything besides holding on.

  The first radiation pulse had passed them with the light of the explosion, but the slower, heavier, more deadly radiation would be just a trifle behind it. The shields ought to be able to handle the heavy particles. But they would have to hold long enough to protect the ship from the larger debris, from the bits and pieces the size of molecules to dust particles to shrapnel to fist-sized chunks of metal. The debris moved slower than the radiation, but was still coming at them fast, far faster than rifle fire.

  “Estimate, time until front of blast wave arrival!” Koffield called.

  “Sensors blanked, sir. No current data.” How hard had the intruder hit the scattershot? What was the closing rate and angle? She could have read all that off the lightblast, given time and sufficient data. But not in half a second, and not with her detectors blanked.

  “Estimate and count to and past first possible moment, based on last data.”

  “Estimate first possible, twenty seconds. Nineteen. Eighteen—”

  “Five-second interval,” said Koffield, almost snappishly. “Hell of a time to go blind.” He gave up staring at the displays. Old data could tell him nothing new.

  “Defense systems!” he called. “Shield status, projected duration.”

  “Shields at stable point, drifting down to ninety-seven percent. They’re taking a good peppering from the heavy particles, but holding stable. Projected remaining duration, twenty seconds.”

  “Fifteen seconds to first possible blast wave contact,” Sayad announced.

  Close. Damnably close. The shields would start to die just as the cloud of blast debris swept past them. There was not time enough to stop and restart the shields. It would be suicide to try, anyway. The heavy particles still streaming past would be enough to give them fatal doses of radiation sickness. Sayad could almost imagine that she could hear, feel, the heavy particles pinging .off the electro-mag shields. But that was nonsense, of course.