Underlying the phenomena of our everyday world, and indeed of all processes in the universe, are the elementary particles and their interactions. What are the elementary particles and how do they interact with each other? What determines their nature — the world have been different? Why are there atoms, light and semiconductors? What new wonders of the physical realm remain concealed from humanity?

The 20th Century was an extravaganza of discovery that deepened our perception of matter and enlarged our view of the universe. Atoms, nuclei, and quarks revealed their secrets. Stars, galaxies and black holes provided a new context for our place in the universe. At the same time these discoveries led to a new generation of questions, technological advances have brought to the threshold of learning some of the answers — answers that will lead to a revolution in our understanding of nature as profound as the discovery of relativity and quantum mechanics in the last century.

Particles and their interactions are governed by symmetries; sometimes by symmetries with imperfections. The defects in the symmetries are crucial, leading to some particles being heavy and some light, some interactions being strong and others weak, and to much else besides. What new force causes these imperfections in the symmetry? This force is quite unlike the known gravitational, electromagnetic, strong and weak forces, and the present theoretical challenge to understand it will soon be resolved by experiments in the United States and Europe. The new force may involve a new field filling all space — if the whole universe was bathed in something like a magnetic field — it may herald a new understanding of space and time. An earlier revolution in our understanding of space and time was Einstein's 1905 Theory of Relativity, with unfamiliar notions leading to profound consequences, for example for nuclear energy and antimatter. As we draw towards the centenary of this discovery, perhaps in our own time we will discover supermatter or excitations of matter proclaiming the existence of extra dimensions of space quite unlike the large ones so familiar to us.

It is commonly believed that these familiar dimensions of space became large during an early era of the universe when length scales underwent a period of exponential inflation. What is the physical theory underlying such catastrophic early cosmic behaviour, and how can it be tested? From studies of the gravitational behaviour of the universe as a whole, we have learned some remarkable results: most of the matter in the universe does not shine and is dark, and there is a field energy pervading all space causing the universe to expand at an ever faster rate. What are the mysterious dark matter and dark energy, which dominate the universe, but are so unlike the particles and fields that we measure in the lab on Earth?

The physics of particles and the physics of the universe must be one. The quantum realm and the geometric spacetime realm of gravity must be reconciled. The reconciliation, which eluded Bohr and Einstein, can now be glimpsed in string theory. Despite considerable progress of the last two decades, string theory remains in its infancy. How do the familiar electron and photon emerge as the low energy limits of the oscillation of the string? How could the theory have produced an era of cosmic inflation, followed by our more gentle times of a calmer expanding universe? What keys are needed to unlock the potential of the theory, allowing calculations of particle masses and force strengths? What new unexpected phenomena might it predict to be lurking near at hand?

For Physics at Berkeley, the start of the 21st Century was marked by the creation of the Berkeley Center for Theoretical Physics. Designed to offer the possibility of exciting, fundamental scholarship at the highest level, it provides a level of excellence and breadth that attracts the very top young researchers in the field as faculty, postdoctoral fellows, and visiting scholars. These world-renowned experts on particle physics, cosmology and string theory have come together to address many of this century's new questions involving matter and space time in a setting that builds on the traditional strengths of Berkeley.

There was a time in the last century when the State of California had the ability to provide for most of the University's needs. Today, we live in an age of annual budget battles and the search for a quick payoff, but it is the work that counts. The Berkeley Center for Theoretical Physics was established for the long run, and its basis is steeped in a rich history of cutting-edge scientific discoveries.

Fundamental advances in basic science cannot be predicted, nor can their consequences. The discovery of the first elementary particle, the electron in 1897, was a complete surprise, and many of its most important applications, i.e. electronics, lay decades away. Einstein once asked, "What impels us to devise theory after theory?" His answer, "Because we enjoy comprehending... there exists a passion for comprehending just as there exists a passion for music."

It is remarkable that this music is a profound basis for change in human society, but funding through government grants alone is no longer sufficient to support the key element of this music — the collaboration between the best minds in the field, including faculty, students, postdoctoral fellows, and visiting scholars. To continue along the path of what have been arguably the greatest human achievements of the 20th Century, will now depend on private philanthropy. With your help, the University of California at Berkeley will continue to lead the way among world-class research institutions.


Graphics on this page are courtesy of High Energy Physics Advisory Panel available here.