Cecil Moore wrote:
Gene Fuller wrote:
Cecil Moore wrote:
What is it about interferometers that you don't understand?

Nothing at all.

Well then, please explain why, in the interferometer
example, the energy rejected by the standard output
due to destructive interference, is intercepted on
its way back to the source and made available as
constructive interference at the non-standard output.

I presume by "interferometer example" you mean the experiment outlined
on the following web page.

http://www.teachspin.com/instruments...eriments.shtml

Is there some mystery here? The explanation is very straightforward. No
need for any philosophy, magic energy incantations, counter-balanced
construction and destruction, or special short-lived created and
immediately canceled waves. You can probably add as many of those
elements as you like, but Occam says it isn't necessary, and they add
nothing of substance.

Look carefully at the primary beam splitter in the center of the sketch.
Suppose that the "standard output" is at a constructive maximum. Part
of the light returning from MA1 is turned by the beam splitter toward
the standard output. That light does not undergo any phase shift at the
beam splitter, since in the configuration shown the reflection is
internal at the "far side" of the beam splitter. Part of the light
returning from MB1 travels directly through the beam splitter, and there
is no phase shift. The two light beams are in phase as they leave the
beam splitter heading toward the standard output. Constructive
interference happens. (The mirror positions are adjusted as needed to
achieve the maximum.)

What then happens to the portion of the light that heads back toward
auxiliary beam splitter near the source? (Remember, these are beam
*splitters*. I hope there is no question about why light might travel
back toward the source.) In this case part of the light returning from
MA1 travels directly through the primary beam splitter and it undergoes
no phase shift. Part of the light from MB1 is turned by the beam
splitter, and in this case there is a phase shift due to the external
reflection. In general this phase shift would be around 180 degrees. As
the web page points out, other shifts are possible, depending on the
exact details of the beam splitter. In any case, we now find two beams
that are out of phase heading back toward the source. This of course
leads to destructive interference and darkness.

Obviously everything shifts depending on the position of the mirrors and
the length of the interferometer paths. As mirror MA1 is moved the
standard output becomes dark while the auxiliary output becomes bright.
I hope there is no question about that part.

As I said a day or so ago, there is nothing at all on this web page that
is even remotely surprising or controversial. This is all very
straightforward and well understood.

Is there something else you had in mind when you asked the question?

73,
Gene
W4SZ