A classical model is presented that, due to electric field, when a particle is passing double slits, a self induced force can arise so that the particle is impacted by both slits simultaneously to form concentration varying patterns. While this model may not precisely account for the interference fringes, it raises a question on the origin of the diffraction patterns and imposes restrictions on wave-particle duality.

Aside from Bell’s inequality, QM and local real theory have other specifications that can be observed in experiments. To explore these specifications, we re-examine EPR paradox to show that non-locality arises from the absence of location variable. Our analysis are then applied to several reported experiments. 1) In a known short range Bell experiment with high detection efficiency, portion of the presented data agrees more with local real model than with QM. 2) The so called non maximally entangled state in several experiments are essentially partially entangled photons, with a large local real part helping the violation of Bell’s inequality, and the reported event counts deviate from expected entanglement model. 3) In long range EPR experiments for closing locality loophole, interactions with local real apparatus prior to measurements put the entanglement in question.

We demonstrate that, under Lorentz transformation, the frequency and the energy of an electromagnetic wave train form a linear relationship, emulating the equation of photon energy E = ℏω. This shows that wave-particle duality of light is compatible under space time transformation.

Aside from Bell’s inequality, entanglement and local real model have other aspects which are expected in experiments. Analysis on a) the physics concept of entanglement and b) precise interpretation of experiments shows that 1) In a reported loophole-free violation of Bell inequality, the transition of wave function from odd parity to even parity reveals that the experiment is performed on the spin of a pair of local real nitrogen vacancy (NV) centre. 2) The equivalence between rotating spin by θ and rotating measurement basis by −θ is not applicable in entanglement case, thus in long range entanglement setups for closing locality loophole, the operation of rotating spin followed by measurement puts the entanglement in question. 3) Fair sampling assumption arises when a finite sample is used to represent the entire population space, thus it is a basic requirement of statistical experiment, fair sampling loophole can not be closed.