Thanks for the most interesting discussion of slinkys, "ether", and
seismology. But I'm a little vague on what you mean by "vibrations".
You're describing a field whose orientation isn't necessarily at a right
angle (transverse) to the direction of propagation (as in a TE or TM
mode wave), yet whose "vibrations" are nevertheless at a right angle to
the direction of propagation. So the "vibrations" are in a different
direction than the field. I'd like to learn more about this phenomenon,
but I can't find "vibrations" in the indexes of any of my
electromagnetics texts. Do they have another name?

Roy Lewallen, W7EL

Peter O. Brackett wrote:
. . .
Visualize a long "slinky" coil attached to the wall. Shake one end up and
down to create a transverse wave in which the slinky moves up and down.
Push and pull on the end to produce compression and dilution to cause
longitudinal waves in which the slinky does not move up and down but in
which the distance between turns moves back and forth. This slinky analogy
sort of illustrates the differences. Meanwhile in electromagnetic wave
phenomena you have as well as the most common TEM mode which is only
transverse vibrations, also there exists a plethora of TM and/or TE modes,
or even in the near field, where the fields may not be at right angles to
each other or to the direction of propagation, but the vibrations are still
talways transverse, i.e. not compressive-dilutive.
. . .