The nature of physical objects cannot be clarified independent of our concepts of space and time. We present arguments to show that neither the classical 3D space - 1D time nor 4D space-time of special relativity provide a satisfactory theoretical framework to this end, as we encounter non-classical objects. The general relativity is perhaps able to accomplish this task. But, it does so only at the expense of rendering the empty physical space neither isotropic nor homogeneous. Waves are not candidates to represent fundamental objects. We use the celebrated example of Compton scattering to argue that the full description of the experiment makes use of both wave-like and particle-like behavior in the early quantum-mechanical formulations. The later quantum field theoretical descriptions of the same phenomenon abandon causality. We present model arguments from modern particle physics experiments that the photon may be a hadron, at least part of the time.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.