Your underlying motivation to pooh-pooh and to utter rather
silly and childish remarks makes you seem like a fool.

Why do you behave in that way?


Brian Reay wrote:
Someone offers you genuine information, on topic to your post, and you see
it as "pooh-pooh". I can see why you are a "slow learner", to use your own
description of yourself.

A laser will diverge in the absence of a medium.
Degree of collimation and coherence both are factors in divergence and you
are jumbling together a raft of factors that I supect you don't understand
and I know you don't want to learn about.