Richard Clark wrote:

Cecil Moore wrote:
"All of the photon energy present in these (canceled) waves
must somehow be recovered or redistributed in a new direction, ..."

Was and has been Orthogonal to the direction of propagation - nothing
has changed.

The Melles-Groit web page says: "In the absence of absorption or scatter,
the principle of conservation of energy indicates all "lost" reflected
intensity will appear as enhanced intensity in the transmitted beam."

This is in regards to a thin-film anti-glare coating. If a laser beam
is perpendicular to the plane of the thin-film, the reflected beam
and the transmitted beam will lie in a STRAIGHT LINE. Where did you
get the idea that it has to be "orthogonal to the direction of
propagation"?

There's only one other direction in a transmission line and that's
back toward the load.

This does not follow from the other.

Sure it does. There are only two directions possible in a transmission
line and if energy traveling toward the source is "redistributed in a
new direction", there exists only one other direction available, i.e.
toward the load.
--
73, Cecil, W5DXP