This volume contains the proceedings of a symposium held in honour of Jean-Pierre Vigier at York University, Toronto, Canada, in August 1997. The topics of the contributions range from quantum mechanics and its interpretation, to particle physics, electromagnetic theory, relativity and gravity, and the relationship between inertia and the zero-point electromagnetic oscillations that constitute the vacuum. The fifty-two articles are arranged under the following categories: astrophysics-cosmology, the Aharonov-Bohm effect, electrodynamics, gravitation and inertia, light and photons, mathematical physics, particle physics and quantum theory. Audience: This book will be of interest to graduate-level students and researchers.