Could anyone please explain the mechanism of diffraction of electrons through the single hole. Have a look on the picture attached. It says if we would shoot only one electron at a time, the pattern would be the same. Things which are confusing me: 1. If the source of emitted electrons is far from the grating (holes), then the direction of "flying" electrons is perpendicular to the plane of holes. According to De Broglie particles propagate as waves and not as a straight line. Since electrons are not accelerating, they are not emitting any waves by themselves. Thus the electron can be seen as a flying sphere (combined waves in all planes) right?. Why the electron is changing its direction when passing through the whole? What influence on changing of its direction? I understand how diffraction works in uniform medium (Huygens–Fresnel principle), but... see 2 2. According to Huygens–Fresnel principle, every point to which a luminous disturbance reaches becomes a source of a spherical wave. Since the experiment on the picture happens in vacuum, then what is a "point to which a luminous disturbance reaches" in vacuum? Like I understand if its in water or any other uniform medium, but what can be hit in vacuum?