Cecil Moore wrote:
Jim Kelley wrote:
You seem to be implying that there's something different about how
these electromagnetic waves change direction compared to other
electromagnetic waves. Why is that?

There is something different but not unusual. We don't
often observe wave cancellation of visible light waves
because of the problem of getting coherent beams of light
perfectly aligned. Yet, we experience RF wave cancellation
every time we adjust our antenna tuners for a Z0-match
because the perfect alignment of coherent RF waves inside
a piece of coax is an automatic given.

[Example snipped]

Cecil,

This is a rather curious notion. Where did you get the idea that waves
must be perfectly aligned to "cancel"?

Suppose I set up an experiment in which two coherent laser beams are
misaligned by, say, one picoradian. The phases are adjusted so that the
waves "cancel" in the region of overlap. This is much the same as the
Java picture you like to reference from the FSU Magnet Lab. Any
measurement that might be made in the overlap region would show the
destructive interference, or "cancellation" if you wish. However, the
beams are not perfectly aligned, so eventually the overlap ceases, and
the individual beams proceed on toward infinity. I believe most people
would agree that those exiting beams would not be altered by any
interaction or interference that might have occurred in the lengthy
overlap region. (That is a very easy experiment that can be conducted in
any elementary optics lab.)

OK, so now we fine tune the illuminating mechanism so that the two beams
are perfectly aligned. Are you saying that there is now some fundamental
physical difference, and that the beams indeed cancel?

What is the equation that provides such a dramatic change resulting from
an adjustment of one picoradian? What reference is there for this
dramatic change mechanism?

73,
Gene
W4SZ