Twistor

by Cramer, John; Wolfe, Gene;

  'It only seems that way,' said David, handing Paul another plate. ' "RF" just means "radio frequency" or high-frequency electricity. We're using something like a TV transmitter to pipe electromagnetic energy into our experiment. We're driving the system with high-frequency radio waves.'

  'What happens during the commercials?' asked Elizabeth with an impetuous grin.

  'We have a special circuit that cuts out the commercials, the game shows, and the wrestling matches,' David said, laughing. 'We prefer to use soap operas and new-wave music. It's much smoother.'

  'Paul told me that you've been working with warm superconductors,' said Elizabeth. 'I remember hearing about them five or six years ago when they were making the covers of Time and Newsweek. What ever happened to them?'

  'Oh, they're still around,' said David, 'but the floating trains and the superfast computers described in the magazines are taking a bit longer than was advertised. Warm superconductors were special in the first place because they have a special crystal structure called a layered perovskite. It's a flat crystal plane like a checkerboard with copper atoms in the centers of the squares. The copper atoms in the red squares have spin up and those in the black squares have spin down.'

  'Wait, David, let me get this straight,' said Elizabeth, holding up a hand. 'As I recall, atoms have a permanent "spin" rotation about their axes that also gives them a magnetic field like a little compass needle attached to each atom. If the needle points up or down, then the atom has spin up or spin down. Right?'

  'Right,' said David. The atoms of copper resemble little spinning tops, and can point either way.'

  Elizabeth nodded, measuring coffee beans into the grinder.

  'OK. About two years ago it was discovered,' David continued, speaking more loudly over the noise of the grinder, 'partly by our own dear Professor Allan Saxon and his students, that in these checkerboard crystals of some of the warm superconductors there's a new and previously unsuspected kind of ordering. Waves called holospin waves move through these crystals by changes in the spin directions, rather like the waves you see when the wind blows over a field of wheat. You know, like "amber waves of grain." But these waves are special because instead of being like a regular wave pattern, they're more like a hologram.' He handed Paul some silverware.

  'That isn't much help, David,' said Paul. 'The workings of holograms are not widely understood. I'm not sure that I understand how they work in every detail. There are some tricky phase aspects of the wave interferences—'

  'Never mind the details,' David interrupted. 'The only thing you need to know about them is that if you break off a small piece from a big hologram, it still shows the same picture as the whole thing but with less resolution. That's because the holographic ordering, the encoding of the picture, is spread out over the whole thing rather than localized in any one place on the hologram.

  'And it's the same with the waves that we make in our superconductor samples. It's called "holospin order," and the wave disturbances that move in funny ways through the crystals are called "holospin waves." ' He paused to run the plastic scrubber over the inside of a pot.

  'Allan Saxon told me that those are the hottest thing in condensed matter physics just now,' said Paul. 'He said that a holospin transmission cable made from one pair of warm superconductor strips could carry simultaneously an almost unlimited number of messages of very high bandwidth. It will revolutionize communications, he said, and there are lots of other applications, too. Should I believe him?' He shook some detergent into the dishwasher, closed its door, and turned it on.

  They dried their hands and adjourned to the living room. Paul stirred up the fire he had started in the stone fireplace. David stared into the fire, musing. 'Sure you should . . . at least in this case. The application potential is real enough,' he said. *I turned down a tenure-track faculty job at a pretty good university to come here for a second postdoc so I could work with Saxon and get in on the ground floor of this. And we're beginning the second generation of experiments. These will be the ones where we learn to fully understand the phenomenon: how it works, and what it's good for.'

  'But you're having problems?' said Elizabeth.

  'Yeah,' said David. 'Our equipment is lying to us. Vickie thinks some funny resonance in the vacuum-readout electronics is the culprit. That would explain all the facts, but it doesn't feel right to me. I've used almost the same hardware in a dozen other experiments, and I never saw anything like this. It's true that we're making some pretty strange electromagnetic fields. The field vectors are rotating, precessing, and jumping according to an intricate program that we set up. But there's no reason that that should produce what we're seeing.

  'Anyhow, Vickie is now checking things out while I'm over here wining and dining. I promised I'd be back about midnight to take over. I'll work a few more hours tonight and try to flush some bugs out of the system. As a psychologist, you should understand this, Elizabeth. If you interact closely enough with a complicated system, it'll eventually tell you what its problems are. And somehow it works best in the wee hours.'

  'You guys have your own pagan religion,' said Paul, shaking his head. 'Instead of sacrificing sheep, you sacrifice sleep. Do you suppose there's any chance at all that you're seeing a real effect, not just an instrument glitch?'

  'Look,' said David, 'we're talking about a volume of empty space about the size of a baseball acting as a vacuum pump and absorbing lots of energy at the same time. There's no physics I know about that could account for that.'

  'I know some physics that could, if the energy density were, say, 1032 electron-volts per cubic centimeter,' said Paul. He smiled ruefully. 'Some of the oddball superstring theories I've been playing with lately would seem to say that you can make space itself do tricks if you fill it with the right amount of energy. Trouble is, that "right amount" hasn't been around since the Big Bang.'

  'We ain't making any Big Bangs in my lab, buddy!' said David. Then he paused and smiled. 'You might say we're close, though . . . the power's only off by thirty orders of magnitude.' He winked at Paul. That's closer than some of your predictions, I believe.' They both laughed.

  Elizabeth disappeared in the direction of the kitchen and soon returned with a tray of steaming coffee cups. 'David,' she said, 'if you're going back to work tonight, you'll certainly need some of this.'

  'I'm afraid it's going to take more than coffee to get the job done tonight, Elizabeth,' said David, taking a cup and saucer from the tray. 'You have anything that makes you smarter instead of just more wide awake?'

  'Wish we did!' said Paul. 'I could use some of that myself.'

  4

  Thursday Midnight, October 7

  David pulled into the Fifteenth Avenue Northeast entrance to the central parking garage. At this time of night there was no guard in the glass-walled booth as he drove past it to the short ramp up to the A level. He selected an empty spot near the southeast corner, parked and locked his car, and climbed the garage stairs to the exit at the corner of the Administration Building. Across Rainier Vista he could see lights in the windows of their lab in Physics Hall; Vickie's still at it, he concluded, smiling to himself. As he walked down the broad granite stairs and headed across an open space, the bell in the campanile to the north slowly tolled twelve. Midnight, he thought. He was still feeling pretty sharp. Maybe he could get something done tonight.

  He unlocked the outer door with his building key and let himself in, then walked along the dimly lit hallway to his laboratory. It was an unusually quiet night, he observed. None of the usual night owls seemed to be working in the other labs tonight.

  Victoria looked up from the console as he let himself in. David noticed that she looked unusually tired. 'Maybe I should have called you at the Ernsts and told you to save yourself a trip,' she said. She told him what she had been doing. 'And I found two new frequencies where the same thing happens. The vacuum improves, and the RF power shows a load increase,' she said. 'It's spooky!'

  'I didn't
want to say anything that might have dampened your enthusiasm,' said David, 'but your vacuum gauge resonance theory smelled wrong to me then. Driving over, I was wondering whether we could be making a cyclotron resonance with free electrons in the sample volume. Maybe stray electrons get up some speed, collide with gas molecules in the vacuum, ionize them, and the fields sweep them out. That would explain both the power loss and the improved vacuum.'

  Vickie frowned and shook her head. 'If that works,' she said, teasing, 'you'd better patent it quick. It makes a far better vacuum pump than this one we bought for several thousand dollars.'

  'Yeah.' David sighed, nodding agreement. That point had occurred to me also. I guess it's a lousy theory. I'm grasping at straws, Vickie. Maybe if I play with this miserable beast for a while I'll get some better ideas. Anyhow, you look as if you could use some rest. We can't have you expiring from exhaustion before we even get you a Ph.D. You have to wait 'til you're a postdoc for that.'

  Victoria looked at David, frowning. 'Don't worry about me; worry about yourself,' she said. 'I know your disgusting work habits very well, David Harrison. You're quite capable of forgetting the time and working all night. Remember that you have a class to teach tomorrow. You can't afford to hang around here for more than an hour or so, no matter how interested you get in our hardware problems. I'm going to set this timer, see. When it buzzes, you have to go home. OK? Promise?'

  'Vickie, if I'd wanted to work with a mother hen, I'd have gone into zoology,' said David, slightly annoyed. 'I'm well aware that I can't work much longer. That damned eight-thirty lecture is only about eight hours away now.

  'But speaking of mother hens, how are you doing with Flash?' asked David, seeking to change the subject. Vickie's sixteen-year-old brother was now living in her rooming house. He had come to Seattle at Vickie's widower father's request after a brush with the law in southern California. Last month Sarah and David had gone with Vickie to SeaTac Airport when young William Gordon arrived. He was a tall scrawny kid with acne and Vickie's red hair. They'd had a nice dinner at David's apartment that evening, and David had tried to interest him in physics. But William, or 'Flash,' as he had insisted on being called, seemed more interested in David's new portable Macintosh III computer and his collection of science fiction hardbacks. He had told David that if they ever let him out of high school he was going to get a fast degree in computer science and make lots of money.

  Victoria shrugged on her jacket and her backpack. She frowned and said, 'William is doing OK, I guess. He just started as a senior at Roosevelt High School, and he got into the classes he wanted. His teachers say he's turning in assignments on time and doing well in class. And the Seattle police, unlike the L.A.P.D., don't pay him a visit every time some hacker cracks a bank machine.'

  'So he's reformed?' David asked.

  'I've got my fingers crossed,' she answered. 'William claims to have learned his lesson, and he gives the appearance of being a serious student. I haven't the time to watch him continuously, of course, any more than Dad could in Santa Monica.'

  He nodded, waiting.

  'David,' she said, 'I don't think William has completely given up hacking.'

  'Why?' he asked.

  'Because last night when I got home I noticed that my modem was still warm,' she said. 'He may have just been dialing into bulletin boards, but he might be trying to crack commercial systems again. I'm worried.'

  She looked at her watch, frowned, waved at David, and left. For a minute David looked unseeing at the closed door, musing over how cold and empty the room suddenly felt with Vickie not in it.

  Then he turned his thoughts back to the present problem, the glitch in their experiment. He seated himself at the experimental console and moused up the control program. Scanning several of the new parameter files that Vickie had generated, he selected one and tried it. He didn't have to look at the vacuum gauge to know that the problem was still there. He could hear the reed relay click as the automatic mechanism changed vacuum scales. He began to experiment. He tried changing the field in the superconducting magnet; he tried altering the rotation rate of the field precession system; he tried playing with the relative phases of the electric-mode and magnetic-mode driving fields. Nothing helped.

  He'd been working for about an hour when he noticed one peculiarity. Watching a field pickup with an oscilloscope, he saw with surprise that the field was not making a single 'twist' as it was programmed to do. Instead it was 'tumbling,' repeating the rotation cycle over and over again. He'd found a bug! Backtracking the symptom, he discovered that it originated not in the electronics but in the programming. A few days earlier he'd made a small 'improvement' in the control program. Apparently this change had brought with it an unwanted side effect: instead of making a single twistor rotation pass, the field rotation was cycling again and again.

  Relieved that he had at last found a fixable problem, David corrected and recompiled the program, then activated the field cycle. The result was a disappointment. While the vacuum excursion was now much reduced, it was still there. And the strange loss of RF power was now bigger than before. The program bug had not created the problem, it had only aggravated some other glitch that was still present. It just didn't make any sense.

  David, feeling frustrated, got up from the console and walked around the room, topping off the liquid nitrogen and liquid helium reservoirs inside the apparatus and tightening a brace to reduce vibrations from the mechanical first-stage vacuum pump. As his hands worked automatically, he had an idea: if you can't twiddle parameters to make things better, why not see what it takes to make them worse? The rotating field volume of the system was carefully adjusted to be well inside the boundaries of the sample holder and the magnetic guide field. But suppose the problem was coming from some stray field getting where it didn't belong. By readjusting a few currents he could make the field volume bigger – much bigger, in fact. There was plenty of drive power for that. They had been quite conservative in estimating the power needed, and as a result the driver units were considerably overdesigned. If he could make the problem worse, then perhaps its source would become more apparent.

  He returned to the control console and moused up the program that he and Vickie had developed to design and model the unusual coil configuration of the apparatus. He set the nonlinear least-squares search feature of the program to find settings that duplicated the same twistor field shape but with a diameter that was, say, eight times larger.

  The computer settled into its search procedure. It took a while. It usually needed about twenty minutes for its central processor to search out optimum parameters in the complex parameter space of possibilities. While the search code wandered about in its arcane way, mapping the parameter space and seeking a minimum in the chi-squared goodness-of-fit value, the system's powerful display processor had nothing to do. So, for the user's amusement, Vickie had arranged the program to produce a perspective view of the chi-squared space being searched, a spectacularly colored graphical representation showing a mathematical terrain of tall mountains, rolling foothills, and broad deep valleys. The colors of the surfaces were selected using an algorithm that, on a blue-washed background, mapped mathematical mountains with white tops, brown central regions, and green bases.

  As the lengthy search proceeded and the contours of the terrain were filled in, David settled back to wait for the result. He realized that the emerging scene with its snowy mountain summits, brown slopes, and green valleys looked very much like the Cascades he had explored the previous summer. He remembered his first climb. The winter snows of the central Cascade Range near Seattle had melted enough for safe mountaineering, and Paul had invited him along on 'an easy Class Three climb.' He remembered it well . . .

  The four of them had been climbing Kaleetan, a minor two-thousand-meter peak in the Central Cascades. Paul had been in the lead; David was second, in the novice position; followed by Rudi Baumann and George Williams, both quantum-gravity theorists.

  The
monotony of the uphill plodding had lulled David into daydreaming. He was just fitting his boot into the next step that Paul had provided when he heard a shout. Back along the white slope marked with dark footsteps he saw George, last on the rope and heaviest of the party, momentarily frozen in the act of losing his footing as a snow step crumbled away. As David watched, George flailed, pivoted, and toppled into a downward slide, head first on his side. He twisted, pivoting on an elbow as he planted the short wide blade of his ice axe in the snow to halt his fall. That, it seemed, was a mistake; George was falling too fast for that maneuver. The broad blade bit out a shower of snow, and the ice axe jerked and was wrenched from George's grip, his acceleration continuing unchecked. A clearly enunciated 'Shit!' echoed resoundingly from the nearby rock walls.

  David felt his heart speed up from an involuntary adrenaline spurt. He watched as George's red-clad figure moved leisurely down the slope, trailing the dark rope, moving toward the jagged rockfall below, twisting as he maneuvered into a stomach-down, head-up position. George was trying without much effect to slow his fall by digging toes and elbows into the snow. The rope straightened, stretched, and stiffened, shedding snow and moisture as it became a vibrating line. George was slowed momentarily as the impact hit Rudi, now kneeling in the snow, the narrow spike of his ice axe planted about halfway up the blade.

  But David could see a problem developing. The climbing rope, which should have absorbed the shock at Rudi's waist, well centered on his braced position, had somehow become draped over his shoulder instead. The impact levered him up and backward, and now he was sliding down the snow slope head down on his back, his axe blade pointing uselessly toward the sky.

  I'm next, thought David. We're like dominoes. Those two falling now are both heavier than I am. George must mass about one-hundred-twenty kilos, and Rudi perhaps ninety. When that quarter ton of meat hits the end of the rope, I'll never be able to stop them. They'll drag me off too, and then there will be three of us falling. We'll pull Paul off, and that will make four. We're going to end in a pile of broken bodies on those sharp rocks down there. In a day or so maybe someone will find what's left of us. We're going to die right here, right now. And this was only supposed to be a Class Three climb!