If light was composed of classical particles...
Here particles all moving in the same direction from very far away hit
a barrier with one or two openings.
If light was composed of classical waves...
Here a straight wavefront from very far away hits
a barrier with one or two openings.
Light is a quantum wave that radiates and interferes with itself like a wave but interacts discretely like a particle
yThis can't really be visualized correctly for a number of reasons,
but here is a kind of visual analogy:
G.Horton-Smith, gahs at k-state.edu, 2010/02/15