This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Feynmans QED probability amplitudes. Richard Feynman using little clocks timing each event instead of the formal complex numbers light source emits light which bounces off the mirror in blue and reaches the detector An obstruction between and gray rectangle avoids direct path between source and detector The graph below represents