The God Particle

by Leon Lederman

  The third super was the search for the site of the Super Collider. Fermilab was one of the contenders largely because the Tevatron could be used as an injector to the SSC main ring, an oval track with a circumference of fifty-three miles. But after weighing all considerations, the DOE's select committee picked the Waxahachie site. The decision was announced in October 1988, a few weeks after I had entertained a huge meeting of the Fermilab staff with my Nobel jokes. Now we had quite a different meeting as the gloomy staff gathered to hear the news and wonder about the future of the laboratory.

  In 1993 the SSC is under construction, with a probable completion date of 2000, give or take a year or two. Fermilab is aggressively upgrading its facility in order to increase the number of p-bar/p collisions, to improve its chances of finding top, and to explore the lower levels of the great mountain the SSC is designed to scale.

  Of course, the Europeans are not sitting on their hands. After a period of vigorous debate, study, design reports, and committee meetings, Carlo Rubbia, as CERN's director general, decided to "pave the LEP tunnel with superconducting magnets." The energy of an accelerator, you will recall, is determined by the combination of its ring diameter and the strength of its magnets. Constrained by the seventeen-mile circumference of the tunnel, the CERN designers were forced to strive for the highest magnetic field that they could technologically visualize. This was 10 tesla, about 60 percent stronger than the SSC's magnets and two and a half times stronger than the Tevatron's. Meeting this formidable challenge will require a new level of sophistication in superconducting technology. If it succeeds, it will give the proposed European machine an energy of 17 TeV compared to the SSC's 40 TeV.

  The total investment in financial and human resources, if both of these new machines are actually built, is enormous. And the stakes are very high. What if the Higgs idea turns out to be wrong? Even if it is, the drive to make observations "in the 1 TeV mass domain" is just as strong; our standard model must be either modified or discarded. It's like Columbus setting out for the East Indies. If he doesn't reach it, thought the true believers, he will find something else, perhaps something even more interesting.

  9. INNER SPACE, OUTER SPACE, AND THE TIME BEFORE TIME

  You walk down Piccadilly

  With a poppy or a lily

  In your medieval hand—

  And everyone will say

  As you walk your mystic way,

  If this young man expresses himself

  In terms too deep for me,

  Why, what a singularly deep young man

  This deep young man must be.

  —Gilbert and Sullivan, Patience

  IN HIS "DEFENSE OF POETRY," the English romantic poet Percy Bysshe Shelley contended that one of the sacred tasks of the artist is to "absorb the new knowledge of the sciences and assimilate it to human needs, color it with human passions, transform it into the blood and bone of human nature."

  Not many romantic poets rushed to accept Shelley's challenge, which may explain the present sorry state of our nation and planet. If we had Byron and Keats and Shelley and their French, Italian, and Urdu equivalents explaining science, the science literacy of the general public would be far higher than it is now. This, of course, excludes you—not "dear reader" anymore, but friend and colleague who has fought with me through to Chapter 9 and is, by royal edict, a fully qualified, literate reader.

  People who measure science literacy assure us that only one in three can define a molecule or name a single living scientist. I used to characterize these dismal statistics by adding, "Did you know that only sixty percent of the residents of Liverpool understand non-Abel-ian gauge theory?" Of twenty-three graduates randomly selected at Harvard's 1987 commencement ceremonies, only two could explain why it's hotter in summer than in winter. The answer, by the way, is not "because the sun is closer in summer." It isn't closer. The earth's axis of rotation is tilted, so when the northern hemisphere is tilted toward the sun, the rays are closer to being perpendicular to the surface, and that half of the globe enjoys summer. The other hemisphere gets oblique rays—winter. Six months later the situation is reversed.

  The sad part about the ignorance of the twenty-one out of twenty-three Harvard grads—Harvard, by God!—who couldn't answer the question is what they are missing. They have gone through life without understanding a seminal human experience: the seasons. Of course, there are those bright moments when people surprise you. Several years ago, on Manhattan's IRT subway, an elderly man sweating over an elementary calculus problem in his textbook turned in desperation to the stranger sitting next to him, asking if he knew any calculus. The stranger nodded yes, and proceeded to solve the man's problem for him. Of course, it's not every day that an old man studies calculus next to the Nobel Prize-winning theoretical physicist T. D. Lee on the subway.

  I had a similar train experience, but with a different ending. I was sitting on a crowded commuter train coming out of Chicago when a nurse boarded, leading a group of patients from the local mental hospital. They arranged themselves around me as the nurse began counting: "One, two, three—" She looked at me. "Who are you?"

  "I'm Leon Lederman," I answered, "Nobel Prize winner and director of Fermilab."

  She pointed at me and sadly continued: "Yes, four five, six ..."

  But seriously, the concern over science illiteracy is legitimate, among other reasons because of the ever-increasing linkage of science, technology, and public welfare. Then, too, there is the great pity of missing out on the world view I have tried to present in these pages. Though still incomplete, it has grandeur, beauty, and an emerging simplicity. As Jacob Bronowski said:

  The progress of science is the discovery at each step of a new order which gives unity to what had long seemed unlike. Faraday did this when he closed the link between electricity and magnetism. Clerk Maxwell did it when he linked both with light. Einstein linked time with space, mass with energy, and the path of light past the sun with the flight of a bullet; and spent his dying years in trying to add to these likenesses another, which would find a single imaginative order between the equations of Clerk Maxwell and his own geometry of gravitation.

  When Coleridge tried to define beauty, he returned always to one deep thought: beauty he said, is "unity in variety." Science is nothing else than the search to discover unity in the wild variety of nature—or more exactly, in the variety of our experience.

  INNER SPACE/OUTER SPACE

  To see this edifice in its proper context, we now make an excursion to astrophysics, and I must explain why particle physics and astrophysics have in recent times been fused to a new level of intimacy, which I once called the inner space/outer space connection.

  While the inner-space jocks were building ever more powerful microscope-accelerators to see down into the subnuclear domain, our outer-space colleagues were synthesizing data from telescopes of ever greater power, supplied with new technologies for increasing sensitivity and the ability to see fine detail. Another breakthrough came with space-based observatories carrying instruments to detect infrared, ultraviolet, x-rays, gamma rays—in short, the entire range of the electromagnetic spectrum, much of which had been blocked by our opaque and shimmering atmosphere.

  The synthesis of the past one hundred years in cosmology is the "standard cosmological model." It holds that the universe began as a hot, dense, compact state about 15 billion years ago. Then the universe was infinitely or almost infinitely dense, infinitely or almost infinitely hot. The "infinite" description sits uncomfortably with physicists; all the qualifiers are the result of the fuzzy influence of quantum theory. For reasons we may never know, the universe exploded and has been expanding and cooling ever since.

  Now how in the world did cosmologists find that out? The Big Bang model arose in the 1930s after the discovery that the galaxies, collections of 100 billion or so stars, were all flying away from one Edwin Hubble, who happened to be measuring their velocities in 1929. Hubble had to collect enough light from distant g
alaxies to resolve the spectral lines and compare them to lines of the same elements on earth. He noted that all of the lines shifted systematically toward the red. It was known that a source of light moving away from an observer would do just that. The "red shift" was in fact a measure of the relative velocity of source and observer. Over the years Hubble found that all galaxies were moving away from him in all directions. Hubble showered regularly, and there was nothing personal in all this; it was simply a manifestation of the expansion of space. Because space is expanding the distances between all galaxies, astronomer Hedwina Knubble, observing from the planet Twilo in Andromeda, would see the same phenomenon—galaxies flying away from her. Indeed, the more distant the object, the faster it is moving. This is the essence of Hubble's law. It implies that if you ran the film backward, the most distant galaxies, moving faster, would close in on the nearer objects, and finally the whole mess would rush together and coalesce into a very, very small volume at a time presently estimated as about 15 billion years ago.

  The most famous metaphor in science asks you to imagine yourself a two-dimensional creature, a Flatlander. You know from east-west and north-south, but up and down do not exist. Cast up-down out of your ken. You live on the surface of a balloon that is expanding. All over the surface are the residences of observers—planets and stars, clustered into galaxies all over the sphere. All two-dimensional. From any vantage point, all objects are moving away as the surface continually expands. The distance between any two points in this universe increases. That is how it is in our three-dimensional world. The other virtue of this metaphor is that, as in our own universe, there is no special place. All points on the surface are democratically equivalent to all other points. No center. No edge. No danger of falling off the universe. Since our expanding-universe metaphor (the balloon surface) is all we know, it is not a case of stars rushing out into space. It is space carrying along the whole kaboodle, which is expanding. It isn't easy to visualize an expansion that is happening everywhere in the universe. There is no outside, no inside. There is only this universe, expanding. Into what is it expanding? Think again of your life as a Flatlander on the surface of a balloon. The surface is all that exists in our metaphor.

  Two major additional consequences of the Big Bang theory finally wore down the opposition, and now a fair consensus holds. One is the prediction that the light of the original incandescence—assuming it was hot, hot—would still be around as remnant radiation. Recall that light consists of photons, and the energy of photons is related inversely to their wavelength. A consequence of the universe's expansion is that all lengths are expanded. The wavelengths, originally infinitesimal, as befits high-energy photons, were thus predicted to have grown to the microwave region of a few millimeters. In 1965 the embers of the Big Bang, the microwave radiation, were discovered. The entire universe is awash with these photons, moving in all possible directions. Photons that started a journey billions of years ago when the universe was much smaller and hotter ended up on a Bell Laboratories antenna in New Jersey. What a fate!

  After this discovery it became crucial to measure the distribution of wavelengths (here, please reread Chapter 5 with the book turned upside down), which was eventually done. Using the Planck equation, this measurement gives you the average temperature of the stuff (space, stars, dust, an occasional beeping satellite that escaped) that has been bathed in these photons. According to the latest (1991) NASA measurements from the COBE satellite, this is 2.73 degrees above absolute zero (2.73 degrees Kelvin). This remnant radiation is also strong evidence of the hot Big Bang theory.

  While we are listing successes, we should also point out difficulties, all of which were eventually overcome. Astrophysicists have been carefully examining the microwave radiation in order to measure temperatures in different parts of the sky. The fact that these temperatures matched up with extraordinary precision (better than .01 percent) was a cause for some concern. Why? Because when two objects have exactly the same temperature, it is plausible to assume that they were once in contact. Yet the experts were sure that the different regions having precisely the same temperatures were never in contact. Not "hardly ever," but never.

  Astrophysicists are allowed to speak so categorically because they have calculated how far apart two regions of the sky were at the time the microwave radiation observed by COBE was emitted. That time was 300,000 years after the Big Bang, not as early as one would like but as close as we can get. It turns out that these separations were so large that even with the velocity of light there was no time for the two regions to communicate. Yet they have the same temperature, or very close to it. Our Big Bang theory couldn't explain this. A failure? Another miracle? It became known as the causality, or isotropy, crisis. Causality because there seemed to be a causal connection between sky regions that never should have been in contact. Isotropy because everywhere you look on the grand scale you see pretty much the same pattern of stars, galaxies, clusters, and dust. One could live with this in a Big Bang model by saying that the similarity of the billions of pieces of the universe that had never been in contact was a pure accident. But we don't like "accidents." Miracles are okay if you invest in the lottery or are a Chicago Cubs fan, but not in science. When they appear we suspect that something grander is lurking in the shadows. More on this later.

  AN ACCELERATOR WITH AN UNLIMITED BUDGET

  A second major success of the Big Bang model has to do with the composition of our universe. You think of the world as being made of air, earth, water (I'll leave out fire), and billboards. But if we look up and measure with our spectroscopic telescopes, we find mostly hydrogen, then helium. These account for 98 percent of the universe. The rest is composed of the other ninety or so elements. We know by our spectroscopic telescopes the relative amounts of the lighter elements—and lo!—the BB theorists say that these abundances are precisely what one would expect. Here is how we know.

  The prenatal universe had in it all the matter in the presently observed universe—that is, about 100 billion galaxies, each with its 100 billion suns (can you hear Carl Sagan?). Everything we can see today was squeezed into a volume vastly smaller than the head of a pin. Talk about overcrowding! The temperature was high—about 1032 degrees Kelvin, a lot hotter than our current 3 degrees or so. And consequently matter was decomposed into its most primordial components. A plausible picture is of a "hot soup," or plasma, of quarks and leptons (or whatever is inside, if anything) smashing into each other with energies like 1019 GeV, or a trillion times the energy of the biggest collider a post-SSC physicist can imagine building. Gravity roared in as a powerful (but presently little understood) influence at this microscopic scale.

  After this fanciful beginning, there was expansion and cooling. As the universe cooled, the collisions became less violent. The quarks, in intimate contact with one another as part of the dense glob that was the baby universe, began to coagulate into protons, neutrons, and the other hadrons. Earlier, any such union would have come apart in the ensuing violent collisions, but the cooling was relentless, the collisions kinder and gentler. By age three minutes, the temperatures had fallen enough to allow protons and neutrons to combine and, where earlier these would quickly have come apart, now stable nuclei formed. This was the nucleosynthesis period, and since we know a lot of nuclear physics, we can calculate the relative abundances of the chemical elements that did form. They are the nuclei of very light elements; the heavier elements require slow "cooking" in stars. Of course, atoms (nuclei plus electrons) didn't form until the temperature fell enough to allow electrons to organize themselves around nuclei. The right temperature arrived at about 300,000 years. Before that time we had no atoms, and we needed no chemists. Once neutral atoms formed, photons could move freely, and that is why we got our microwave photon information late.

  Nucleosynthesis was a success: the calculated and the measured abundances agreed. Wow! Since the calculations are an intimate mix of nuclear physics, weak-force reactions, and early universe cond
itions, this agreement is very strong support for the Big Bang theory.

  In the course of telling this story I have also explained the inner space/outer space connection. The early universe was nothing more than an accelerator lab with a totally unconstrained budget. Our astrophysicists need to know all about quarks and leptons and the forces in order to model evolution. And, as we pointed out in Chapter 6, particle physicists are provided data from Her One Great Experiment. Of course, at times earlier than 1013 seconds, we are much less sure of the physics laws.

  Nevertheless, we continue to make progress in our understanding of the Big Bang domain and the evolution of the universe. Our observations are made 15 billion years after the fact. Information that has been rattling around the universe for almost that amount of time occasionally stumbles into our observatories. We are also aided by the standard model and by the accelerator data that support it and try to extend it. But theorists are impatient; the hard accelerator data give out at energies equivalent to a universe that has lived 10−13 seconds. Astrophysicists need to know the operative laws at much earlier times, so they goad the particle theorists to roll up their sleeves and contribute to the torrent of papers: Higgs, unification, compositeness (what's inside the quark), and a host of speculative theories that venture beyond the standard model to build a bridge to a more perfect description of nature and a road to the Big Bang.