A report on high-energy physics.

Physicists who use accelerators call their subject "high-energy particle physics," and their goal is the complete understanding of the physical universe and all of its parts. This includes identifying the fundamental or the simplest objects and the forces that act between them. It also includes an understanding of the origin of the universe and of its subsequent evolution, and there is clearly no small humility here. In fact, if I were to try to characterize the problems of our field, I would say that the primary problem of the field is the arrogance of theoretical physicists and the second problem is the shortage of funds. The humility question gets a bit worse, because my theoretical colleagues assure me that there is a wide belief that success is very close at hand-that we are rather near a complete theory that contains the most fundamental, the truly elementary, objects and that understands the forces and the buildup of the layers of matter from the primary constituents to the nuclei, to the atoms, to the molecules, the cells, the people, the stars, and the galaxies and, also, the origins from the beginning of time to the infinite future. That is the sweep and the arrogance of our friends. In 1968, an Encyclopedia Britannica article commented that speculations about the underlying structure which composes the observed particles had not led very far in the 1960s. The 1982 comment is that experimental and theoretical work over the past 15 or so years has resulted in a widely held opinion that we are in the midst of a very revolutionary epoch in our effort to understand the structure of matter in terms of fundamental constituents. A perhaps useful analogy to what we are doing (with acknowledgements to Lucretius) is the analysis of the structure of a library. If you were asked What are the fundamental constituents that make up a library? you might be hasty and say "Books." And then someone will point out that a book is really a very complicated object. Some books are more complicated than others. Continuing to look for a finer ingredient, you quickly dismiss chapters and paragraphs and sentences as not being very useful as fundamental objects. Finally, you get to words, and you are encouraged because, in fact, at the entrance to the library, there is a dictionary which compiles all words. By selecting words in a somewhat orderly manner and putting them together according to certain rules (grammar) with certain aesthetic or other motivations, you organize these into sentences which make the chapters which make the books which make the library. Someone will eventually point out that the dictionary is very thick and that you really only need 26 letters, at least in some countries, and 26 letters is a much handier compendium of things to arrange and put together. In appropriate combinations, subject to certain laws (spelling), these make all the words which make. . . .. Today, any child will tell you that you do not need 26 letters. All you need is a 0 and a 1 or a dot and a dash. In appropriate combinations, dots and dashes make the 26 letters. Now, if it makes no sense to take the dot apart, then you have arrived at the truly fundamental, structureless item, and it is these structureless items and the rules by which you compose with them to make all these things that is the goal of the particle physicist in the search for a world view. It is a recent practice for theorists to call their world view the "standard model." In 500 B.C., the standard model was much simpler. It had four objects, called air, earth, fire, and water. It also had two forces which Empedocles called love and strife. I do not know whether those were named as whimsically as we name things today. Not to rest, we, at the Fermi Laboratory, tried this model. We succeeded in getting hot, bubbling mud, which was not everything in the world. In 1800, Prout's law looked very promising. It said that everything was made of hydrogen, and so, indeed, the light elements obeyed that rule very icely until one came to chlorine which did not fit at all. Later on, the standard picture had the periodic table of elements. This periodic table suggested a cyclic internal structure. Later on, in 1900 when the electron was discovered, we knew that the periodic table, the organization of elements, was a sign or a signal that there was a rich underlying structure which, of course, was the electron shell structure. By 1920, things looked very simple. We knew about the lectron, and we knew about the proton, and we knew that by combining electrons and protons in different ways and subject to certain rules we could understand the structure of the periodic table. There were two forces. We knew about gravity which was not relevant to the structure of elementary particles, but we also knew about electromagnetic forces which bind the electrons into the atom. We had a very elegant picture. There were afew problems with it. Nitrogen-14 gave troubles especially with the quantum theory. We had to invent different kinds of electrons, some inside the nucleus and some outside. Also, there were a few facts that were not accommodated by that world view. Radioactivity was not accommodated, and nobody understood why the sun continued to shine. How many people considered these fundamental and how many dismissed them as details I do not know. As you will see, there are modern parallels. Anyway, it was a very elegant standard picture, even if it did not explain everything. Now, before you give too much credit to the theorists, you should know that the history of particle physics is really a history of inventions, of a series of accelerators of increasing energy and, of course, of instruments for observing and measuring the objects that the accelerated projectiles produce (Table 1). The first accelerator was Gallileo's. It is called a "nearly vertical linear accelerator," and it accelerated particles to about 1/10,000 eV. This was quickly replaced by the Bunsen burner which reached energies of the order of several electron volts. Then followed the x-ray tube and, skipping over many steps, the invention in 1930 by Lawrence of the first cyclotron. There