Abstract Young's 1D‐double‐slit experiments have been extended to 2D‐cross‐double‐slit experiments, in which more than one 1D‐double‐slits are crossed at the same spot and each 1D‐double‐slit creates the interference pattern independently. In this article, the varieties of the double‐slit/cross‐double‐slit/grating experiments are presented. The universal novel phenomena are: (1) the interference/diffraction patterns (hereafter referred as “patterns”) are curved; (2) the patterns are expanded; and (3) the patterns created by the tilt‐double slits are inclined to the axis perpendicular to the axis the diaphragm rotates around. The directions of the patterns curved towards are determined by whether the diaphragm rotates clockwise or counter‐clockwise. To determine the directions, right‐hand rule and left‐hand rule are proposed. The degrees of the expansions depend on both the original orientation of the double slit and the angle of the diaphragm rotates. The formulars to calculate the expansion and the inclination of the patterns are derived. The experimental observations support the formulars. The novel phenomena not only make the Feynman's mystery more mysterious, but also provide the comprehensive data/information to theoretical study of the mystery of double slit experiments. Furthermore, the novel phenomena may have potential applications, for example, in antenna system. The phenomenon of the expanded Airy pattern is presented.