Thoughts about the Career of a Graduating PhD in Physics
Martin C. Gutzwiller
Abstract: The preparation for the PhD in physics seems quite narrow for various reasons. It is then essential for the student to experience scientific life not only in a different environment, but also in another area of physics
The education of a young scientist is well defined. The minimum is 4 years of undergraduate and at least 4 years of graduate studies, to be completed with a PhD thesis. Its theme is generally suggested and then supervised by a professor who is a specialist in the matter. Nowadays the young person will be encouraged to continue his/her work as a post-doctoral researcher in an available university.
For many physicists, this postdoctoral continuation is repeated several times, until a more permanent (and better paid) job in the same specialty is found. Sometimes it looks as if the main recommendation for such a job is the stubborn pursuit of the main topic in the PhD thesis. My scientific life (from about 1950 to 2000) looks as if I had tried to change my interests in the beginning as often as possible. In spite of the changed conditions in today’s physics, I still insist on the great importance for every student to become aware of various special fields, and try out one or two. The work in different areas of physics requires different skills, and the atmosphere in a government or industry laboratory does not compare at all with the universities. A young person has to have some practical experience before deciding her/his lifestyle. The best time is right after the batchelor’s degree, without a foregone conclusion to get a PhD thesis. After the PhD degree, a challenging research job for several years will show another part of the world. Teaching in a good university is still accessible when in one’s thirties.
The up and down in my scientific life would sound like a self-serving recommendation. But the main reason for my insistence comes from the deep change in the life of physics over the second half of the 20th century. The Second World War had brought physics in America to the top of the sciences world-wide, no less! Physics departments in the universities, however, and even research in the government laboratories had not increased to the same extent. Industry came to the conclusion that hiring physicists could be quite helpful. Jobs became available in unforeseen areas.
The first event to change all that was "Sputnik", the first artificial satellite to circle the Earth, launched by the Soviet Union in fall 1957. President Eisenhower launched a crash program, and physics got everything it wanted, in jobs and equipment for universities, government, and industry. These sudden movements were soon taken over by European institutions that had recovered from WWII. The 1960’s were roaring times "physically", and politically as well! The universities held on stubbornly to their increase.
The second event was not so obvious, but it started toward the end of the 1960’s, and settled down in the 1970’s. It is more subtle, but very profound. Particle physics was promoted already during WWII to explain the structure of the nuclei. After the war, much bigger accelerators were built in the hope of better understanding the nuclear structure. But by the 1970’s any such explanation was beyond the usual theoretical quantum field theory. At the same time the cost of the machines for the necessary experiments ran into unreasonable sums that could be used for other pursuits in the sciences.
Right now, or if a round figure is required, let us say since the year 2000, the foundations of physics seem impenetrable. The big experiment at CERN still hopes to find something understandable. For over 20 years, however, theoretical explanations are off in some speculative garden where nothing can be secured by experiment. The research toward the deepest foundations in physics has proved to be beyond our human effort. Even the "standard model" for particle physics is beyond mathematical analysis in depth.
For many readers it may look outrageous to interpret the history of physics in this radical way. Such a viewpoint appears more acceptable if physics is compared with its two neighbors on the left, mathematics and astronomy, as well its neighbors on the right, chemistry, geography-geology-geophysics. These four companions have been alive in humanity for thousands of years. Their scientific territories have grown in modern times while remaining in the human sphere of accessibility and interest, quite unlike physics.
The professional life of an individual in the "hard" sciences lasts about 50 years, from age 20 to 70. The student has to absorb the ever increasing knowledge, and to learn the methods as well as invent new ones in the progress of science. Teaching becomes a central and enjoyable occupation, not only daring experiments and grandiose explanations. It is tempting to continue this activity for the remaining life. But modern science requires more than pure knowledge. New ideas have to be worked out, their ramifications explored, possible applications tried out, and connections with other fields established. The usefulness, the cost, the distribution, and perhaps even social consequences have to be evaluated. These additional activities cannot be neglected; they require special talents that demand a grown up person with a wider view of the world.
Unfortunately, all these normal activities for physicists may lead to the most extravagant problems, such as the two main types of atomic bombs, and even to the intense radiation phenomena with their destructive intentions. The more down-to-earth mechanics and thermodynamics, once they got into the hands of the physicists in the 19th century, turned into automated weapons and their horrible results. The number of physicists working in these fields is considerable. By contrast, chemical warfare was limited by the required conventions, although it had been tried a few times.
The professors in physics should occasionally lead their students outside the strict teaching plans. They have to develop a deeper insight and a broader understanding concerning the transition from the "natural philosophy" of Newton to modern "physics." The 19th century ended in the unified concept of electro-magnetism. The idea of the atom had been sponsored by the chemists for a long time, and the physicists finally proved it in their own fashion. Relativity and quantum mechanics then lead to nuclear physics. Particle physics was supposed to explain the structure of the nuclei. But that never happened; since 1950, nuclear physics is a purely empirical science.
In the spring of that year I graduated from the Swiss Federal Institute of Technology in Zurich (ETH of Einstein fame). The year before I had spent 6 months to write the required "Diplom-Arbeit". I had asked Wolfgang Pauli to be my supervisor, and he asked his post-doc, Felix Villars (later at MIT where he started a new program on physics in the life sciences), to discuss my work as needed. I was supposed to calculate the anomalous magnetic moment of the proton-neutron with the coupling by a charged, vectorial pi-meson. After Schwinger and Feynman had obtained the anomalous magnetic moment of the electron, it was natural for a beginning graduate student to try his hand on the proton-neutron problem.
The ETH still lived as before WWII, and was organized like its famous French model. The department of mathematics and physics had 10 full professors of mathematics, 2 in physics (Pauli and Scherer), and 1 in astronomy. They gave all the required courses; quantum mechanics was not taught. I had to learn it from working through some famous textbooks all by myself. Sommerfeld was the easiest, Pauli and Dirac were the hardest. There was plenty of time to study hard, and not to fool yourself, even if you could quote whole sentences. This experience gave me courage and conviction when I had learnt some new specialty of physics. Like a dog, there is pleasure in chewing on a bone to get the finest piece of meat.
After the Diplom, I could have started on a PhD thesis. But there were no scholarships or assistantships available, and I decided to earn some money. I got a job helping to install the first microwave telephone link between Zurich and Geneva. By summer 1951, I got a scholarship at the physics department of the University of Kansas. Max Dresden’s first job was there, and I much appreciated the spirit at KU. I continued working in quantum field theory, and was searching for a job in 1953. Although I had an immigration visa, times were not good for foreigners, and I ended up at the geophysical laboratory of Shell Oil Company in Houston, Texas.
Research was dominated by the geologists and the chemists. Publishing any new results was quite limited. Nevertheless the laboratory had a dozen young physicists directly from the universities, where they had done a PhD thesis in an esoteric topic. They were asked to get familiar with down-to-earth problems, and participate in work already on the way. I was asked to study dislocations, well known one-dimensional singularities in a crystal lattice. They are responsible for crystal growth and plastic flow. Calcites and dolomites under high pressure were studied in the laboratory.
After a couple of years, I was asked to get familiar with the magnetism of sedimentary rocks, i.e., very small special crystals inside a non-magnetic rock. Then I got involved in the propagation of waves in layered formations. Of particular interest was dropping a heavy steel plate on a hard dry ground, a time-dependent excitation on a surface with mixed boundary conditions! This was before the times of Fortran, on machines with very poor memories. The on-going experiments had a close relation with these problems.
Another industrial giant, IBM, had opened a research laboratory near Zurich, and I was eager to bring my family back to Switzerland. The freedom of work there was remarkable, and I was allowed to publish some of my results from Houston. Whatever results I now found were to be published, as long as I did not lose myself in esoteric physics. I was inspired to study magnetism in metals. I formulated the problem as in quantum field theory, with a projection that prevented the electrons from crowding on a lattice site. That idea is still appreciated to explain high-temperature superconductivity.
After 3 years my whole family went back to the USA in 1963. I had a chance to work at the original IBM lab on the campus of Columbia University, and teach a course in the engineering department. I started a new project, when I became convinced that the limit between classical and quantum mechanics had not been properly examined. Feynman had found a method using his path-integral. He had tested it only in very special cases, not even including the H-atom. The most important information for the spectrum were the classical periodic orbits (PO). I was inspired by the founder of the laboratory, an astronomer computing planetary orbits, and particularly the lunar trajectory. It was based on a single PO in a special case of rotating the coordinates with the Sun. The classical PO’s produced approximate quantum spectra for various atomic and molecular problems. That led me straight into classical as well as quantum chaos. Chaos and the history of physics and astronomy became my work and hobby until 2000.
This discovery happened as I turned 45, 20 years after my graduation from the ETH. I continued some other work. I mostly enjoyed meeting a whole new bunch of colleagues who found new features and mathematical riddles in quantum chaos. Many have dedicated their lives to this wide open field. I often miss their connection with physics, in favor of an abstract mathematical model. There are also solid–state physicists, chemists and engineers of various kinds, for whom vibrations in some " crooked" body are important. Gadgets of that type are very popular in the effort to miniaturize computers, etc. I enjoy very much talking to them, because it puts me in direct relation with everyday objects.
Frankly, I wish that more of my younger colleagues could also profit from the boom of research in the last 50 years. But the world of physics has changed profoundly. The great industries stopped the boom more than 20 years ago. IBM got rid of many people my age (late 60’s) with a mixture of threat and promise (which they have kept now for 15 years!). Progress now comes from highly specialized skills, always directed toward imaginable goals. Shell is hiring geologists and chemists as before, but needs many engineer-scientists with education in special fields and down-to-earth skills. There should be some space for bright young people who want to work.
The boom in the universities had its ups and downs, but the teaching staff has remained very large, whereas the government laboratories are less lucky. Both are hit hard by the second great event in physics of the last 50 years. The short history of physics shows how it concentrated on the very foundations of the hard sciences. This special role for physics has come to a halt now since 30 years. The insight we have gained has led us into a vast morass. Even my short experience with calculating the magnetic moment of the proton in 1949, is still unsolved theoretically, even computationally.
I wonder sometimes how many physics professors in the universities are worried for the future of their students. The boom of the last 50 years has lead into a vast and confusing territory of high-energy particles and all the associated areas like cosmology, both in experiments and theory. Special efforts are required so that the students do not simply hold out for a teaching position at a university. I also wonder sometimes what will happen with physics at extremely low temperatures. It does not require nearly as many people and facilities, and our understanding does not end up in a morass.
A last general impediment for students to find some work is the increasing specialization of their professors. Many have been in the same field for a long time, and their competence in other areas is limited. The list of open jobs each month at the end of Physics Today always gives tight descriptions. What about a list for recent PhD’s specifically to work in another field?
I have tried to paint a picture of the present state of physics, historically and philosophically. The consequences for students are not obvious from the attitudes and experiences of their professors. The effective training in a particular specialty creates engineers and technicians rather than individuals with the capacity to work in different areas. The universities have to find ways for broadening the mind of their PhD students, and create opportunities where this aim can be realized. It may be harder now after 50 years of boom with the added difficulty of large areas of physics slowly phasing out.
Martin Gutzwiller is an IBM Research Staff Emeritus, and is an Adjunct Professor of Physics at Yale University. His current interests are physics, history, and philosophy. He can be reached at MoonGutz@aol.com