The delayed-choice entanglement swapping experiments, both in space and time, are casually explained at a single quantum level by using the `wave-particle non-dualistic interpretation of quantum mechanics'. In order to achieve this, the actual mechanisms involved in the Wheeler's delayed-choice experiment and Einstein's spooky-action-at-a-distance are uncovered from the quantum formalism. The continuity in the motion of any individual quantum particle, due to the constants of motion, is responsible for the outcomes of Wheeler's delayed-choice experiment. The purpose for the existence of spooky action in Nature is to strictly maintain the conservation laws in absence of exchange-interactions. The presence of a casual structure in the entanglement swapping is shown by detailed analysis of the experimental results presented in the papers, ``X-S. Ma et al., Nature. Phys. 8, 480, (2012)'' and ``E. Megidish et al., Phys. Rev. Lett. 110, 210403 (2013)'', at the level of individual quantum events. These experiments are directly confirming the wave-particle non-duality.
In a time-symmetric form, classical relativistic formulations involve not only a reference time but also relatively advanced and retarded times. This work examines a simple model problem having this structure with the equations of motion having closed-form solutions. The complexity of more realistic models is avoided while the general features are retained. The determinism and casuality of the theory are clearly demonstrated. Some problems associated with the quantization of power series representations using conventional procedures are illustrated and discussed.