On Jun 2, 5:37*am, K1TTT wrote:
what is the physical mechanism for 'interaction' that requires perfect
collimation?

The impossibility of divergence. That collapsed probability function
can occur in an RF transmission line and in an interferometer.
Secondary effects, e.g. noise, are obviously ignored.

coming from a 'primer' and containing words like 'somehow' doesn't
raise my confidence in the explanation.

The "somehow" means that even if someone doesn't comprehend enough to
have "confidence in the explanation", that lack of confidence will
have zero effect on the real-world outcome - the energy involved in
destructive interference wave cancellation will be preserved through
constructive interference based on the conservation of energy
principle. Please feel free to prove them wrong.
--
73, Cecil, w5dxp.com