Simply: physics is the study of the physical universe. From the puzzling quantum world of the very small to the majestic motion of galaxies; from the wonderland world of the very fast to the almost motionless world of the very cold; from our everyday world to the beginning of time—all of the beauty mystery and unexpected delights of the physical universe are the realm of physicists. More fully, physics is many things—a database of knowledge, a collection of paradigms and mathematical theories, a community of researchers, teachers and students and a vital and dynamic social institution affecting all parts of the American and world communities. But, primarily physics is a way of inquiring into the physical universe. From experience, physicists expect that all of the operation of the physical universe can be explained by a few general principles and that these principles can be expressed mathematically. Most people appreciate the beauty of a rainbow, but physicists appreciate the physical beauty and more. They understand the principles of reflection and refraction and recognize other phenomena described by the same principles. Physicists also grasp and relish the mathematics which describe these phenomena. The general population has a very Aristotelian worldview. These ideas of motion, energy and light are based on casual observations and “common-sense” interpretations of these observations. But the operation of the physical universe is subtle and needs a more critical investigation. The worldview of physicists and the general public began to diverge after the work of Galileo Galilei and Isaac Newton, and are now (due to the theories of quantum mechanics and relativity) radically different.

Many people retain an Aristotelian worldview even after a course in physics. This has led to a widespread attempt at physics education reform. The standard texts used in American colleges and universities are now being challenged by texts which are more aware of the need to alter explicitly the worldview of students. The primary organization overseeing the teaching of physics in K-16 grades and at the graduate levels is the American Association of Physics Teachers. The content of physics represents a formidable collection of observations, theories and applications. Authoritative summaries of twentieth-century physics have been put together by the American Physical Society the primary physics research organization in the USA.

The application of quantum mechanics to the structure of matter has revolutionized technology, leading to the transistor, integrated chips, lasers, nuclear power, etc. Major theories, which withstood many tests in the latter half of the twentieth century include the standard model of particle physics, general relativity and the Big Bang. New theories, which began in the second half of the century and are still being developed and tested, include chaos, nonlinear systems and superstrings. Since the Second World War, the American physics community has pursued the Big Science approach to research, and to the education and training of physicists. Yet the collapse of Big Science led to a surplus of physicists on the world market in the early 1990s and caused the physics community to re-examine its goals, education system and research sociology.