On Jun 1, 11:23*am, Cecil Moore wrote:
On Jun 1, 12:52*am, lu6etj wrote:

Returning: Cecil, given A+B=C, do you you see C as result of an
interaction (or mutual action) among A and B, or C a simply result of
A added to B?

Of course, there are all types of "addition", e.g. arithmetic,
algebraic, voltage phasor, Poynting vector, scalar power,
superposition, merging, mixing, ... Which type of "addition" is
appropriate depends upon the nature of what is being added.

Simply put, if A + B = C creates an irreversible result, then A has
(obviously?) interacted with B. If the result is reversible, then A
has not interacted with B. For the great majority of cases,
superposition does not result in interaction. For the great majority
of cases, interference does not result in interaction. For some
(special?) cases, superposition (plus associated interference and wave
cancellation) results in interaction and the result is irreversible.
Non reflective glass is an example of wave interaction. The internal
reflection cancels the external reflection and the energy in those two
reflections changes directions. A Z0-match at an impedance
discontinuity in an RF transmission line is another example. Again, if
two waves are coherent, collimated, and traveling in the same
direction, those two waves will interact, i.e. their superposition
result is not reversible.
--
73, Cecil, w5dxp.com

what exactly is the 'interaction' and why is it unique to that
special coherent, collimated, etc, case? if two waves can 'interact'
in that case there should be other evidence that they can interact in
other situations. just because a+b=c doesn't mean that a and b have
magically disappeared for some reason, in mathematics c=a+b is just as
valid and implies that c is made up of a and b... or using your water
analogy, adding one pint to another pint doesn't magically cause them
to 'interact' in some way, the original water is still there, perhaps
indistinguishable from each other, but still there. it may be
convenient to represent the result of summing an infinite series of
reflections as a single number, but it is not necessary.