Please help me to understand why the path of the photon changes when travels close to a material (for example the edge of a hole)? I'm aware that the path of the photon can be calculated by the QM principles as a probability wave and by this the change of the wavefront follows the Huygens–Fresnel principle. Also I know that because of the uncertainity the smaller size of the hole results bigger possible change in the path. But what is exactly the physical effect that causes the photon to change its path? Maybe the electrostatic force of the protons and electrons that builds up the edge of the hole? Or simply the spacetime curvature that is stronger because of the mass of the close atoms? If there would be a hole inside a plate made of neutrons (like the neutron stars), the photon path would be disturbed also in it? Thank you for your help.