During my 25 years of teaching at CU Boulder, I have enjoyed communicating at all levels with students and colleagues. My experiences have ranged all the way from teaching Introductory Physics to classes of over 400 undergraduates (including many pre-medical students) to working closely with the 13 postdoctoral students from the US and abroad, whom I have brought here over the years. In addition to teaching advanced graduate courses in APAS, I have developed and taught several highly successful innovative new undergraduate courses, including Light and Color, and, most recently, a new "critical thinking" course - Science and Public Policy.

My interest in teaching began long ago, when I was awarded, in 1960, a Woodrow Wilson Fellowship as an entering freshman at Princeton. The Woodrow Wilson was specifically designed to sponsor students exhibiting the potential to be effective future teachers - in order to encourage and help them to develop careers in education. I recall elucidating my teaching philosophy even then, in the essay required as part of the application for that fellowship. My idea then, as now, was that the difficult and abstract ideas contained in theoretical physics could be rendered more accessible by constructing visual paradigms. I suppose, if theoretical physicists divide into algebraic and geometric thinkers, I belong the to the latter classification. Visualizing in my minds eye has been the key to my own understanding of science. I have always endeavored, in my teaching, to express as clearly as possible my own "mental movie" of physical phenomena which underlie complex mathematical descriptions.

Perhaps the ultimate realization of that philosophy was in the course Light and Color, which I developed for undergraduates wishing to satisfy their core science requirement in a novel and exciting manner. This course deals with just a small part of physics, achieving both greater depth and more relevance to the non-scientist. This course deals with the physical and psychological principals of light and color, and has been enthusiastically received by undergraduate majors in journalism, business, theater, film, and other areas.

The story of how I arrived at some of the content for this course is a good example of how teaching profits when the educator simultaneously carries out a vigorous program of basic research. A persistent theme in my research has been studies of the interaction of electromagnetic radiation with matter (usually ionized gases, called plasmas). Recently my theoretical work on time reversal, or phase conjugation of radiation wavefronts in a nonlinear medium culminated in an invited paper before the American Physical Society. While preparing that lecture (another exercise in reducing complex phenomena to simple terms - this time for consumption by colleagues and peers), I recognized the connection between this subject and the dramatic three-dimensional holograms which have captured the imagination of the public. There was a complete parallel between the process I was studying (relevant to communications and manufacturing) and the preparation of holograms, in which three-dimensional images are reconstructed from the phase information inscribed on a thin film or grating. It was shortly afterwards that I realized I could simplify the principles of a hologram to the point where they could make sense to a non-scientist. I successfully incorporated those ideas into a unit on wave diffraction in the Light and Color course I was then developing.

Other subject matter in that course has presented an equal challenge to render comprehensible. The unit on color turned out to require at least as much cognitive psychology as physics. Much of our color perception has less to do with the wavelength content of a scene or image, and more to do with visual processing in the retina and brain. I worked closely with members of the Psychology Department (Jack Werner and his postdoctoral student, Brooke Schefrin) to understand and properly teach those aspects, which have so fascinated other physicists (such as Edwin Land, in his retinex theory of vision). The demonstration that we can assemble a visual image of colorful fruit and flowers from black and white pictures illuminated with only two wavelengths always brings delight, as does the demonstration that superimposing red and green lights gives us the sensation we call yellow. These and other daily demonstrations for my undergraduate Light and Color class have brought to them, in purely visual terms, some of the thrill of unexpected scientific discovery.

A rather different educational experience was encountered in my teaching of Introductory Physics, 2010 and 2020. A large number of undergraduate pre-medical students take this course, which often represents the only obstacle between them and medical school. Although I had been warned that the premeds are fiercely competitive and even unscrupulous, I found nothing of the kind to be true. Most responded to the challenge with hard work and self-discipline, and I found myself getting to know a number of them quite well. Some have told me it was immensely rewarding for them to "catch on" to intimidatingly "difficult" concepts. As a consequence of personal involvement with many of my students, I have been called upon to write dozens of letters of recommendation for Medical Schools, and have followed the (successful) careers of many of my former students in this course through extensive correspondence.

Perhaps the most gratifying experience of my teaching career has been developing and teaching the undergraduate critical thinking course, Science and Public Policy in the Fall of 1994. This course - which received an A+ grade evaluation from its 12 students - was designed to bring into focus the changes in public and government attitudes towards science resulting from the end of the Cold War era. Simultaneous with an historical overview of 100 years of political actions and public opinions towards 20th century science, we intensively studied current events - including analysis of President Clinton's "white paper," Science in the National Interest, and the views of key members of Congress.

Congressman David Skaggs spent an hour and a half in our classroom, answering student-formulated questions concerning changing federal policy towards science. Dr. Carol Lynch, Dean of the Graduate School and CU's Assistant VP for Academic Affairs and Federal Relations, Dr. Richard Harpel came to discuss the mission and role of a research university in contributing to the advancement of science. Most of the 13 undergraduates electing to take this course had little scientific background, but rather were majors in International Affairs, Film Studies and the like. Their enthusiasm and intelligence made Science and Public Policy a joy to teach and convinced me that we scientists have been derelict in our responsibility to educate the public to the needs and benefits of basic research in science.

Another area in which I believe I have made a difference has to do with encouraging and helping women to undertake careers in physics, a traditional male-dominated discipline. Two female Physics Department graduate students, come to mind - Marie Erie and Diana Lininger - both of whom took graduate mathematical physics courses from me while studying nonlinear optics here. Both were top notch students with all A-grades, who, nevertheless, seemed to need (and received from me) a great deal of professional encouragement. Marie is currently teaching at the University of Southwestern Louisiana and Diana recently received her PhD in Physics from CU, after collaborating with me on a number of significant published papers dealing with phase conjugation of radiation in plasmas.

At the graduate level, I have found the connection between teaching and research to be even more profound. Many of my research ideas have been born while I was teaching graduate courses in plasma physics or nonlinear dynamics or mathematical physics. In subsequent years the fruit of my research in these areas often begin to get assimilated into the courses again - as new knowledge, to be communicated to my students for them to build upon in the course of their own professional careers.

An example is provided by my own PhD thesis dissertation, written in the early 60's at Harvard, on the unstable absorption of intense light in plasmas - a subject which has come to be called parametric instability theory. This subject has turned out to be of critical importance in current international efforts to create controlled fusion energy for public consumption by irradiating deuterium pellets with intense lasers. Although parametric instability theory is now included in most textbooks in plasma physics (with my early papers in this area often cited), I began incorporating this subject into my introductory graduate courses in plasma physics long before the current textbook trend.

Finally, I am proud of the career achievements of my many PhD and postdoctoral students. Five have pursued careers as college professors, (one becoming a physics department chair), seven are researchers at national laboratories and universities, four work in technology in the private sector, and two are science writers for the general public.