Cecil Moore wrote:
Gene Fuller wrote:
"the intensity varies between a maximum value Imax = 4I1, and a
minimum value Imin = 0"

Yes, that's essentially what I have been saying. The peak
intensity (irradiance) can be double the intensity of
the combined intensity of both superposed waves.

What B&W *don't* say is anything about two 1 watt waves interacting,
waves exhibiting constructive and destructive interference, cause and
effects relationships, or even energy conservation.

Eugene Hecht calls the last term in the irradiance equation
the "interference term". He talks about "total destructive
interference" and "total constructive interference". The sign
of the interference term indicates whether the interference
is destructive (-) or constructive (+).

All of those are things written by more casual writers, such as Hecht,
Melles-Griot, and the FSU Java dudes. There is nothing wrong with that
type of explanation for simple illustration, but it runs out of gas
when trying to support detailed analysis. One quickly ends up with
silliness such as waves that are launched and then cancel
destructively within a short (but undefined) distance. None of that
nonsense occurs if one simply applies the standard analysis techniques
such as used by B&W.

Exactly what nonsense are you referring to? Please be specific. It
is difficult to defend myself from assertions of "nonsense" with no
specific allegations.

I gather from the above that wave cancellation due to superposition
is against your religion. Since all impedance discontinuities cause
reflections, exactly how and why do those reflected waves cease to
exist? Please be specific.

Cecil,

Waves are useful. However, they are not living objects. They have no
will to survive. There is nothing in the standard E&M science based on
Maxwell's laws that requires waves to be "canceled" if they no longer
exist. There is no conservation law of wave-ality.

If the proper equations are set up and the proper boundary conditions
are applied (not always easy to do), then waves will exist where they
are needed to describe the physical reality and they will not exist
where they are not needed.

There is no need to worry about waves that don't exist.

As for the "nonsense", we had this discussion a few times, including a
couple of months ago. I don't feel like finding the exact messages, but
the gist was something like:

"Wave 4 and wave 5 return toward the source from a match point, but they
are opposite phase and therefore cancel after a short journey."

If you don't recognize that exchange, let's just drop it.

73,
Gene
W4SZ