universe about 1 femtosecond (10-15 sec.) after the Big Bang. Future history books will tell that ours was a time when mankind was able to begin recreating the evolution of the universe following that Big Bang based on solid experimental data, not just on theoretical concepts. The SSC together with our scientifically productive deep space probes will enable us to write further chapters in that history.

The search for the smallest building block that everything is made of drives us to explore physical phenomena within smaller and smaller distances; that necessitates energies higher and higher in inverse proportion to the distance in question. The SSC energy will enable us to examine the physical space within an atto-centimeter (i.e., 10-18 cm., a distance hundreds of thousands times smaller than the size of a nucleus). Since there is no comparable facility being planned anywhere else in the world, the very uniqueness of SSC insures that we will be exploring in an entirely uncharted region. Of course, we cannot predict what kind of new basic particles SSC will definitely produce. It is precisely this major step into the unknown that poses the challenge, captures our imaginations and promises the greatest intellectual rewards. This is why SSC will attract the best creative young minds in the world. It will also restore our cutting edge in both basic science and high technology.

Physics is monolithic. There exists only one universe, our universe. The multitude of forms of all matter obeys only one set of fundamental laws and we are at the threshold of comprehending that set of fundamental laws. To nature, the same set of laws governs the motion of all particles in every aspect of their manifestations-gas, liquid, solid, living beings, planets, stars, galaxies, from the beginning of the universe to the present. In physics, there is no distinction between the different disciplines of our profession. Our aim is to understand that set of laws which governs everything. SSC makes a direct route toward achieving this understanding. It will be our contribution to the civilization of the next century.

2) Are there alternative possibilities, perhaps more modest in size and cost, for advancing the frontiers of our knowledge?

This question has been addressed by the community of high energy physicists--the machine builders, the experimentalists and the theorists--since 1982 in a number of workshops and in collaboration with the Department of Energy through the mechanism of its HEPAP, the High Energy Physics Advisory Panel. Encouraged by the dramatic discoveries at the CERN proton-antiproton collider and by the successful operation of the Fermilab Tevatron--the first superconducting synchrotron--the 1983 HEPAP Subpanel on Future Facilities recommended "the immediate initiation of a multi-TeV, high-luminosity proton-proton collider project with the goal of physics at the earliest possible date." That recommendation may be taken as the beginning of the SSC project.

In March 1986, the SSC Central Design Group, composed of physicists and engineers drawn from universities and national laboratories around the world, produced a site-independent conceptual design for a proton-proton collider with 20 TeV per beam and peak luminosity of 1033 cm-2 sec-1. The two most important ingredients of that recommendation were the conviction of the scientific community that the technology existed to build a reliable and versatile SSC project designed to those specifications and that our scientific understanding provided confidence that the SSC would provide the data necessary for the beginning of an exploration of how symmetries are broken in the basic forces of nature, leading to an understanding of the origin of the masses of all particles.

The SSC Laboratory (SSCL) management has now developed a detailed design, specific to the site selected in Ellis County, Texas by the DOE. This has led to an increase in the estimated total project cost from the 1986 proposal. The cost increase arises primarily from two types of changes. The first type involves recalculation of labor and materials costs and requirements for magnet R&D and instrumentation to assure reliable accelerator performance. The second type involves technical changes (higher injection energy and a larger magnet aperture).

The main reason for the technical change is because largescale accelerators using superconducting magnets have only been in operation since 1986, after the original conceptual design of the SSC was made. Over the last two years, beam measurements at the Tevatron at Fermilab and magnetic measurements at DESY (the German Electron Synchrotron Laboratory) have shown the existence of persistent eddy currents that require correction. Based on this experience, the injection energy and the magnetic aperture were increased in order to ensure a reliable machine. New massive numerical simulations using supercomputers now provide us with detailed knowledge of stability under realistic operating conditions. SSCL judges these technical changes to be required for reliable operation and efficient commissioning of the new accelerator.

As a result of these changes, and in particular the increased cost, the DOE constituted a "HEPAP Subpanel on SSC Physics" "to provide advice on the range of useful machine parameters in order to complete the design phase of the facility."* It was the unanimous recommendation of this panel, and HEPAP itself in accepting and transmitting it to DOE, that implementing these design changes "will ensure confidence in reliable and timely operation of the SSC." The subpanel found that the only cuts that would allow substantial cost savings would seriously reduce the capabilities as well as he scientific potential of the SSC. It recommended unanimously against redesigning the machine with a reduced circumference, and a proportionally reduced energy. The scientific basis for this recommendation was summarized succinctly in the transmittal letter of HEPAP Chairman Professor Francis Low to Dr. James Decker, Acting Director of the Office of Energy Research:

"The Subpanel has concluded on physics research grounds
that any substantial reduction in the energy of the SSC
would compromise our ability to elucidate the nature

of electroweak symmetry, a truly fundamental problem
at the core of the Standard Model. This is because, with
20 TeV beams, there is a confidence that these phenomena
can be studied in whichever form they take, whereas, this
confidence is quickly lost at lower energies. In addition,
no substantial increase of luminosity can make up for a
reduction in energy because no multipurpose detector
is capable of operating well above 1033 cm-2 sec-1, the
design luminosity of the SSC. Only limited purpose,
specially designed detectors can operate at higher
luminosities, and these are not capable of thorough
exploration of the phenomena in question."

In essence the scientific judgment is that such a reduction would unacceptably increase the risk of missing important new physics which is the very goal of building SSC.

Finally we comment that SSC will be a unique facility well into the next century. It will represent a great step by a factor of ten or more beyond any other accelerator now operating or under construction. CERN in Geneva is seriously considering constructing a proton-proton collider in the existing 17-mile-circumference tunnel for its its currently operating Large Electron-Positron (LEP) accelerator. However, the SSC with its 54-mile tunnel and 20 TeV beam energy compared with the 8 TeV design maximum at the CERN design concept, will have the unique potential to explore a wide range of physics in the energy range we believe crucial for our discovering the exciting new phenomena for understanding symmetry breaking and particle masses that are the primary goal of SSC physics.

3) How important is it for 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?

When construction of the SSC was recommended by President Reagan in 1988, and reaffirmed by President Bush in 1989, it was identified as a national goal. At the same time a commitment was

made to maintain support for a strong and broad-based national program. This is an important commitment because high quality scientists and engineers are a national resource of the United States. This technical community is a critical ingredient in our national effort to remain a world leader in technical innovation, to maintain a strong economy and high standard of living, to flourish in competitive high-tech industries, and to meet our goals in national security.

The SSC will be an important component in training and maintaining a U.S. technological edge. For many decades into the next century it will be a unique tool ensuring U.S. leadership and helping train outstanding young American scientists and engineers, and students from more than one hundred American universities in the most sophisticated and demanding new technologies.

More than 50 years ago Ernest Lawrence at Berkeley and Merle Tuve here in Washington built the first large accelerators in the United States in order to study the structure of subnuclear matter. From that day to the present the excitement, the romance of probing nature's secrets with the most fundamental of all questions: "What are we made of?" has attracted the best scientific talent of this country.

SSC will assure continued U.S. leadership in this field that has been a source of great pride as well as a stimulant to important technical innovations in superconducting technologies and computer control of complicated systems. It will also be a boon and an important challenge to the highest-tech leadership of American industries whose experience and expertise will be relied on to build the 54-mile-long system of superconducting magnets and to construct the sophisticated detectors that must be designed to select those few events of crucial importance out of a background of hundreds of millions of interactions occurring each second.