<b>Einstein s Relativity, Simultaneity and Young’s Double Slit Experiment</b> In the present work we have discussed the well known topic of simultaneous passing of photon through both the slit of Young double slit experiment. With the help of the example of Newton’s sailor in the special theory of relativity we have shown that Feynman’s statement in the quantum version of Young’s double slit experiment regarding the simultaneous passage of a photon through both the slits simultaneously needs to be qualified. Simultaneity, double slit experiment 576-579 Issue-4 Volume-1 C. Siam | A. Hazarika | J. Saikia | R. Mahanta | G.D. Baruah