Wave-particle duality, wave function collapse, objective probability and nonlocality constitute four prominent puzzles in modern physics. Although these four topics may appear unrelated, a closer examination reveals that they do share some common assumptions at the foundational level that have characterized physics for the last 100 years... Progress can be made on these four topics only if we understand and possibly revise some long-held assumptions. This essay examines physics from the ontological perspective. Are quantized matter and quantized energy both entities and if so what does that imply? Does matter reside in space and progress in time whereas energy (radiation) resides in time and progresses in space? If so, what does this tell us? Energy has two identities, potential and kinetic. Does mass have two identities and if not why not? The expectation is that answers to these and similar questions will help us understand the connections between the four puzzles listed above. (read more)