Modern Metaphysics

Metaphysics is the science of being and asks the question ``What really exists?'' The answer to this question has been sought for by mankind since the beginning of recorded time. In the past 2500 years there have been many answers to this question and these answers dominate our view of how physics is done. Examples of questions which were originally metaphysical are the shape of the earth, the motion of the earth, the existence of atoms, the relativity of space and time, the uncertainty principle, the renormalization of field theory and the existence of quarks and strings. I will explore our changing conception of what constitutes reality by examining the views of Aristotle, Ptolemy, St. Thomas Aquinas, Copernicus, Galileo, Bacon, Descartes, Newton, Leibnitz, Compte, Einstein, Bohr, Feynman, Schwinger, Yang, Gell-Mann, Wilson and Witten.