Einstein's Bridge

by Cramer, John

  Alice nodded. “Your office is here?” She found that she was distracted, watching his hands and imagining them replaced by metal robotic manipulators.

  “Yes,” said George. “All of us working on the LEM detector have our offices here. There’s a building like this for each pair of experiments.”

  “Pair?” asked Alice. She told herself to focus on what the man was saying so she could ask intelligent questions instead of parroting a word or two.

  George walked to a large diagram of the SSC complex on the wall and pointed. “See the two beam paths here and here,” he said, indicating places on the flat sides of the ring where the red line of the beam split into two. “The machine is designed so that there are a pair of side-by-side experiments that can alternate using the beam. The experiment on one path uses the beam while the experiment on the other path is setting up. Here on the east side of the ring the bedrock under the tunnel can support the most weight, so the biggest experiments are placed here. The west side of the ring has the SSC campus with Administration, the smaller experiments, and the injector complex. Our experiment and SDC have been designated ‘primary’ by the program advisory committee so we share the same beam leg and get 80% of the Collider beam time. Experiments EA-3 and EA-4 are set up on the other leg here. They’re considered ‘tertiary’ and get about 20% of the available beam. We share the LEM Building with the EA-3 people.”

  “So the same beam goes through LEM and SDC?” Alice asked, focusing her camera on the diagram. “Doesn’t one experiment interfere with the other?”

  George laughed. “That’s why your interview with Roy was delayed. One experiment isn’t supposed to even notice that the other experiment is there. But Jake Wang, the spokesman for our collaboration, is absolutely convinced that the SDC people have done something that has degraded the beam we get, and he’s been hassling Roy about it. I think Jake is wrong, but nobody has asked for my opinion in the matter.”

  Alice was surprised at the frankness of his comment. There must be some tensions in the LEM group, she concluded, storing that fact away for later use. She looked at the diagram again. “What experiments are over there by the campus?” she asked.

  “That’s called the West Experimental Campus,” said George. “The ‘secondary’ experiments WA-1 through WA-4 are located over on the west side of the ring.” He pointed to the place on the left side of the diagram where the red line split into two paths. “They each get 50% of the beam, more or less.”

  Alice pointed to two circles near the split. “What are these?” she asked.

  “That’s the injector system. We accelerate protons, first with an RF quadrupole, then with a linac, then in this small magnet ring, and then in the intermediate one, until finally they get up to sufficient energy to be injected into the main SSC ring. We inject half of the protons so that they go clockwise, with the other half going counterclockwise, and then we bash them together. The SSC’s injector system is about the size of the old Fermilab accelerator in Illinois. That used to be the largest accelerator in the world, back in the 1970s. As we say in particle physics, ‘Yesterday’s premier accelerator is tomorrow’s injector, yesterday’s Nobel Prize winning discovery is tomorrow’s background.’”

  Alice smiled as she took notes. “And will there be an even bigger accelerator that will use the SSC as an injector?” she asked.

  George shrugged. “Almost certainly not,” he said. “Perhaps when we get better at building superconducting magnets the SSC might be eventually upgraded with new magnets that make higher fields. That might boost the energy by a factor of two or so. But if particle physics continues to be a hot field and some next-generation accelerator needs to be built, it would probably have to use a new and presently undeveloped technology like plasma-waves or laser acceleration, and it would probably be arranged in a straight line rather than a ring.”

  “Not a ring?” Alice felt disappointed. Accelerating particles in a circle seemed right, somehow.

  “For the past sixty years the highest energy accelerators, from the Berkeley Bevalac and the Brookhaven Cosmotron of the 1950s to the CERN LHC and the SSC of today, have always been synchrotron rings, large circular rings of magnets in which the particles travel in a closed path while the magnetic field is gradually increased as energy is added and they’re accelerated. The SSC, with its 53 miles of ring and 8,600 dipole magnets, is probably the end of that line of development. It’s the last of the giants.” He looked solemn for a moment, then grinned.

  “Or perhaps not. I’m not much of a prophet. At any rate, the SSC is presently the world’s biggest accelerator, and that statement will remain true for at least the next ten years.”

  Alice looked at the diagram, and pointed to an area near the bottom. “Isn’t that a lake?” she asked. “Can you dig a tunnel under a lake without water leaks?”

  “That’s Lake Bardwell,” said George. “It’s down near Ennis. The tunnel goes right under it. Before the tunnel was dug, them DOE geologists swore the Austin Chalk was gonna’ be watertight, but they were wrong. The tunnel leaked lake water and ground water here and there. It cost the DOE a pretty piece of time and money to fix the leaks, but it’s OK now.”

  Alice made more notes.

  George turned from the diagram. “But you’re here to see the LEM detector. Let’s go have a look at it.” He led her down the corridor to another door and down a ramp. Adjacent to the office building was a big open building, like an airplane hangar.

  “This is called the LEM Detector Building,” said George. It was a long rectangular metal structure with a huge corrugated door at one end. A semi was parked at the big door, and a forklift was creating a huge stack of large cardboard boxes marked “SUN MICROSYSTEMS, COMPUTER EQUIPMENT, FRAGILE!”

  As they entered, Alice realized that it felt more like a cathedral than a hangar. It was big, noticeably cooler inside, and the sounds reaching her ears were accompanied by vast hollow echoes. It seemed to be mostly empty space. George led her forward across a concrete-floored loading area to a railing.

  “Look down,” he said.

  Alice looked down and was immediately hit by vertigo. They stood on the edge of a vast pit. It plummeted, level after level. Each level was brightly illuminated by floodlights mounted at the edges of the vast open area. At the bottom of the pit was an enormous pile of equipment. Looking carefully, Alice could just make out tiny moving figures, people and remotes so reduced by the distance that they looked like ... like ants.

  “There it is,” said George, “the LEM detector.”

  “I don’t understand,” Alice stammered. “I thought a detector was a crystal that makes light flashes or something. What I see is a giant irregular mound of equipment.”

  “The mound is the detector,” said George. “It’s very big.”

  “What’s that white column over to the side, with all the wires going to it? It looks like a stack of white bricks.”

  “That’s the electronics stack,” said George. “Each of those ‘bricks’ is a house trailer. That’s where we keep most of the electronics for the LEM detector. It’s stacked up that way to simplify the ducting for the air-conditioning and power wiring.”

  “But I count six layers of ‘bricks’. That means it’s at least six stories high,” Alice objected.

  “That’s right,” said George. “This is a damn big experiment. It’s at the bottom of a shaft two hundred feet deep, it’s as tall as an eight story office building, weighs 50,000 tons, cost $500 million to build, and keeps a thousand scientists busy full time.

  “The particles that come out of that collision have large energies. They’re hard to stop. They don’t bend much in magnetic fields. They’ll travel large distances through anything, depleted uranium or steel or concrete, creating showers of lower energy particles as they go. We need thick walls of heavy metal to slow them down and contain them. The det
ector is so big because it needs to be.”

  “And why is the hole so deep?” asked Alice.

  “Because the SSC is two hundred feet below ground level here, and the detector has to be at the same level as the accelerator. Also the depth makes for better shielding.”

  “Why is there no shielding up here,” Alice asked, watching as the beam crane lowered a large piece of steel into the pit.

  “The radiation goes away when the SSC is turned off, so there’s no problem working on the detector now. And when the SSC is making collisions, only remotes are allowed in the pit and we clear the area over it, except for quick looks.”

  “Then the machine must be off now,” said Alice. “I see people down there.”

  “Indeed,” said George. “The next beam cycle starts tomorrow night. We’re making preparations for it now. Let’s go down and see what’s going on.” He turned and led the way to the elevator.

  As they descended, Alice leaned back against the wall and scribbled detailed notes. Then she glanced down, carefully examined the floor of the elevator car, looking for crevices where an ant queen might be able to hide.

  CHAPTER 3.6

  Counting House

  ALICE sat on the LEM counting house sofa, sipping from a can of diet Coke and reading over her notes. She had followed George around the enormous LEM detector for almost two hours. It had been interesting, but now she felt tired.

  The room was a typical temporary office module: vinyl tile floor, diffused-fluorescent ceiling lights, and textured plastic workspace partitions. But it was filled to overflowing with computer displays and electronic equipment which, she now understood, consolidated a minute distillation of the vast information processed in the multi-story pile of electronics trailers that comprised the electronics stacks down below.

  She sucked at the straw and turned as George, across the room, put away his cellphone and walked toward her.

  “Roy’s done with Jake, but he apparently has another emergency,” he said. “Belinda suggested that you come to her office tomorrow morning, so that the two of you can work out your interview schedule and probably get in to see Roy. Is that OK?”

  Alice nodded. “Sure,” she said, “no problem. I’ll be in Waxahachie for a while. I’ve rented a house there for two months. I’ll spend a couple of weeks here at the SSC doing interviews, then write the Search article and perhaps work on a book project, too.” And I’ll finish the damned thing before I leave, she thought.

  “Very good,” said George. He seemed pleased.

  “I’ve been reading over the notes I made while you were telling me about the reason for building the SSC,” Alice said. “Can I check them with you to make sure I have it straight?”

  “Sure,” said George.

  Alice flipped pages in her notebook. “OK, you people in high energy physics are not satisfied with this QCD theory you presently use, what you called the ‘Quantum Chromodynamics Standard Model’, even though it works well, because it relies on too many arbitrary numbers. Did you say that it has twenty-three adjustable parameters?”

  “Yes,” said George, “the quark masses, the lepton masses, some mixing parameters, the interaction strengths, and some other things.”

  “And you need data from collisions at high energies which should lead you to a new theory that will explain where the masses and strengths come from. You think that the SSC will provide that data because ...” She frowned at her notes. “I’m not sure I caught this part. Something about GeV temperature and boiling water and a change of ‘phase’, whatever that is.”

  George smiled. “In high energy physics we measure temperatures in energy units like GeV instead of Celsius or Fahrenheit.. There’s a special temperature, which we believe is around 400 GeV, 400 billion electron volts, where space itself changes its properties in a second order phase transition, going from the ‘normal’ vacuum of the early Big Bang to a frozen-out vacuum condensate where particles have the masses we measure. ‘Phase transition’ just means space changes its properties, like ice melting or water boiling. The ‘second order’ business means the change is very smooth, with no conspicuous jumps or bumps.”

  Alice nodded, reading her notes. “And you believe the universe made this change early in the Big Bang, after the first millionth of a millionth of a second, and that the SSC will get you to the same temperature.”

  “Yes,” said George, “exactly!”

  “What I don’t understand,” said Alice, “is why you need the SSC data. If the theory tells you so much about what you’re going to measure, why don’t you just calculate it?”

  George laughed. “You sound like a member of the SSC Program Committee. The scenario I just told you comes from an analogy with the theory used in condensed matter physics to explain superconductivity and related phenomena. In principle, particle theorists could use the same theory, except for a few ‘minor’ problems. They don’t understand the nature of what is being ‘condensed’ from the vacuum, or the underlying forces, or the correct mathematical formalism to use. Therefore, anything they do is a stab in the dark. They need data to set them on the right path. Until we get that data here at the SSC, or perhaps at CERN, we’re stuck where we are, with a paste-up theory that doesn’t really explain the fundamental nature of the universe.”

  Alice nodded as she wrote. “And why is it important that it be done now, instead of, say, waiting ten or twenty years until we have better technology and can better afford the expense? As I recall, that’s what some Congressmen who opposed the project were suggesting.”

  George pursed his lips. “You reporters ask nasty questions,” he said. “When the SSC construction was started in 1988 there was a team of people available to build it who had experience from Fermilab and SLAC and Cornell and were ready to move on to the new project. Building accelerators is an art. If you wait ten or twenty years, it becomes a lost art.

  “The same can be said for the people like me who build the detectors and analyze the data. The manpower for the enormous effort needed to successfully build a detector must come from somewhere. That manpower and expertise has been built up in this country since the 1950s, and if Congress had inserted a ten or twenty year delay that would have been lost. The trained people would have gone elsewhere, done other things. They would have been unavailable, perhaps retired or even dead, by the time they were needed.”

  Alice frowned. “You believe that the SSC could not have been built at all, if it had been delayed and hadn’t been started until, say, 2010?”

  George shrugged. “I told you I’m not a very good prophet. All I can say is that the hypothetical people who would start to build the SSC in 2010 would not be the same people who actually built it, and they would surely have far less experience as accelerator builders. There were enough design glitches and startup problems with the SSC as it was. I’m sure that, starting the project in 2010, there would be a lot more.”

  George paused while Alice wrote in her notebook. He smiled, then looked at his watch. “I’m afraid I have to attend a meeting in about fifteen minutes,” he said. “Anything else I can tell you about?”

  “Yes,” Alice said. “Next question. I gather that the SSC Laboratory has invested quite heavily in telepresence and has some leadership in that field. Why?”

  “Well, let’s consider my own case,” said George. “The SSC laboratory is 2000 miles from my university. In the old days, if I wanted to do physics here I’d have to pack up and come with my colleagues, graduate students, and postdocs and either live here most of the year or make nearly weekly trips here. I’d have to spend many days just flying back and forth between Dallas and Seattle, and even more in residence here, away from my classes and most of my students. There was no real alternative. The cost of large particle accelerators is so great that there can be only a few of them, and those who want to use them must rearrange their
lives accordingly. My wife divorced me a few years ago because she didn’t like the rearrangements and finally couldn’t tolerate them.”

  Alice noted that detail. “Like the astronomers who used to travel to Australia or Chile to use telescopes that could study the southern sky?” she suggested. She had interviewed some Florida State University astronomers for the Democrat some years ago.

  “Exactly,” said George, “fifteen or twenty years ago, no one thought the situation would ever change. But then came the miracle of bandwidth.”

  “Bandwidth?” asked Alice. “That has something to do with communication frequencies and TV channels, doesn’t it?”

  “Indeed,” said George. “Over the past few decades the bandwidth, the range of frequencies available for communications and the transfer of information, has been increasing by a factor of ten every five years. There’s a principle that enough small quantitative changes can become a big qualitative change, enough small improvements can add up to a technological revolution. That’s what’s happened with bandwidth. It started with TV conferences. We’d link into other laboratories to listen in on their seminars and group discussions. But as the bandwidth got better and we got fiber-optic links that eliminated the satellite-link time delays, we developed telepresence. Instead of watching on a TV monitor, you can go there with telepresence and experience what is happening on the spot. You can walk into somebody’s office and ask what’s going on. We even have some electronic blackboards where you can scrawl equations and diagrams by telepresence or use robot hands and arms to do the same thing.

  “If you had walked into my office several hours ago,” George continued, “you would have seen me sitting in a black recliner wearing what look like wrap-around sunglasses. We call them “magic glasses”. Lasers from the side-pieces bounce off the front lenses and draw pictures directly on the retinas of my eyes. The unit also has sensors that detect my head and eye movements and points the cameras on the remote accordingly. Because the cameras move when I turn my head, my eyes see just what they would if I were looking at the same scene directly. The vision center of my brain is fooled into thinking it’s all real, and I get an amazing feeling of ‘presence’ that has to be experienced to be appreciated.”