TESTIMONY ON THE SUPERCONDUCTING SUPERCOLLIDER (SSC) before the SUBCOMMITTEE ON ENERGY RESEARCH AND DEVELOPMENT of the SENATE COMMITTEE ON ENERGY AND NATURAL RESOURCES April 24, 1990 S. D. Drell Stanford Linear Accelerator Center Thank you for the opportunity to appear before this Subcommittee to testify on the importance of the Superconducting Super Collider (SSC). The following written statement was prepared in collaboration with Professor T. D. Lee of Columbia University for our appearance on this subject before the Subcommittee on Energy and Water Development of the House Appropriations Committee on March 22, 1990. I wish to submit it for the proceedings of these hearings. The quest to find out what we and our physical world are made of is a mark of civilization that dates back to its very beginning. But it wasn't until approximately 500 years ago--about the time of the discovery of North America--that modern science was born. This came about through the realization that theories must be tested by experiment, and that certain crucial and precise observations can in turn lead to new ideas. Through this strong coupling between experiment and theory, we are able to reduce the great diversity of natural phenomena to a single set of fundamental physical laws. Therefore, any progress that can be made on the fundamental laws will have its effect everywhere and in everything. The important observations on electricity by Ben Franklin in the 18th century and the crucial experiments on the electric and magnetic forces by Faraday in the 19th led to the unification of these two forces by Maxwell later in that century. This, in turn, made it possible for us to understand the fundamental nature of light and its identity as a pure electromagnetic phenomenon. this breakthrough came the development of generators, electric motors, telegraph, television, radar and, indeed, all modern communications. At the turn of our century two crucial, though seemingly esoteric, discoveries were made. One was the experiment by Michelson and Morley in 1887 in this country; the other was the black-body radiation formula by Max Planck in 1900. The former was the basis for Einstein's theory of relativity and the latter laid the foundation for us to construct quantum mechanics. In this century, all the modern scientific and technological developments-nuclear energy, atomic physics, molecular beams, lasers, x-ray technology, semiconductors, superconductors, supercomputers--only exist because we have relativity and quantum mechanics. To humanity and to our understanding of nature, these are all encompassing. Now, near the end of the twentieth century, we must ask what will be the legacy we give to the next generation in the next century? The physicists at the end of the 1890's had a glimpse of a new vista, the existence of exciting and unexplored fundamental areas. Today we also know of the existence of an entirely new class of fundamental forces: the one that is responsible for symmetry breaking. Of this new force, we know only of its existence, and very little else. The new Superconducting Super-collider (SSC) is the key we will use to unlock the door and to take the next big step. As was the case when other great advances were achieved in understanding nature, present progress on the basic physical laws will have a similar long-range and vast impact on the technology of the future. Since the SSC project is of so large a magnitude and so great an expense, it naturally invites a number of serious questions, such as: 1) How important is the SSC in terms of the new knowledge it will provide? 2) Are there alternative possibilities, perhaps more modest in size and cost, for advancing the frontiers of our knowledge? 3) How important is it to the United States to invest in science, and in high energy physics in particular? What practical benefits to society can be expected to result from the SSC? 1) How important is the SSC in terms of the new knowledge it will provide? The very spirit of physics is to explore the unknown. While this makes it difficult for us to predict precisely what we will discover in the future, we are in a position to forecast the minimum payoff. Based on our present knowledge, we are confident that the SSC will explore a specific region in which major new discoveries will be made. The SSC specifications were established with this goal in mind, and experience gained since 1983 has strengthened our conviction of the importance of constructing a proton-proton collider with the beam energy of 20 TeV and luminosity of 1033 cm-2 sec-1, as originally proposed. As a result of truly remarkable progress during the past twenty years, we do have one clear benchmark that is crucial as a guide in setting the energy of SSC at 20 TeV. This benchmark comes from our success in unifying the electromagnetic forces with the weak forces of radioactive decay into a single entity, the electroweak interaction (commonly referred to as the standard model); it is an achievement reminiscent of the unification of electricity and magnetism by Maxwell, referred to earlier. Based on our new theoretical structure for unifying weak and electromagnetic forces, the existence and masses of new particles, the W and Z intermediate bosons, were predicted and confirmed experimentally at CERN in Europe in 1983. From the predictions of this theory, we are certain that exciting new phenomena must appear at the SSC design energy. At present, we know that there exist three classes of forces, the strong force that binds the nucleus together, the electroweak force, and gravity. We know that all these forces are based on symmetry principles, yet practically all these symmetries are broken. The symmetry breaking lies outside the present scope of our understanding. A major task of the SSC is to understand this new class of symmetry-breaking forces. Our present electroweak theory makes it possible for us to say with confidence that 20 TeV is about the minimum energy needed to see the new phenomena in whatever form they may take. The masses of all known particles break these symmetries. Consequently, an understanding of the symmetry-breaking forces will lead to a comprehension of the origin of the masses of all known particles. One of the promising manifestations of symmetry breaking may be the existence of a new type of particles, the Higgs mesons. If so, then in addition we would also discover such new particles. In order to make sure that we can unravel the nature of the symmetry-breaking force in the electroweak interaction, we must measure the scattering between the W and Z bosons, and that we are confident can be done at the 20 TeV design energy of SSC. The recent major advances in particle physics and astrophysics have given us the first-ever experimentally-based glimpse of the history of how the universe has evolved following the Big Bang of some 15 billion years ago. The very high collision energy of the SSC will recreate the physical state that existed in our |