Merlyn wrote:
Sorry RC, but sound is a physical phenomenon, no
matter how you slice it. A sound wave is composed of
particles oscillating back and forth and transmitting
energy in the direction of wave motion by physical
collisions. Light is composed of photons (which may
or may not be physical) and travels directly. Sure,
if you believe in aether theory then light would be
similar to sound.
Sound is a longitudinal wave, light is a transverse wave. Quite apart
from the issue of the medium, that's a rather significant difference.
There's no such thing as a "polarized" sound wave.
(Shockwaves in solid media are something else again, of course.)
However a sonic weapon equivalent
to a laser is not possible due to diffraction angles.
...
Tom, the sonic equivalent of a laser would be a
focused shockwave, but focusing sonic energy like that
does not really work. Plus, to really tear stuff up
you would need a high-frequency oscillating wave, and
the only good way to create a shockwave (bomb) only
gives you one wavefront, not the repeated fronts
needed.
Um .... In _air_ it's hard to build a good sound-gun.
In _water_ the navy's done it very well, and they use it to kill
whales. It's been repeatedly shown to be an effective weapon -- the
only problem with it is that we're not (supposed to be) at war with the
whales just now.
As to difficulties in focusing due to "diffraction angles", that's just
an issue with relatively low frequency sound and small radiators. If
you're willing to use HF sound and/or a good-sized dish you can focus it
quite nicely.
With water, beyond a certain intensity cavitation sets in and your beam
starts losing power to heat. I don't know if there's an equivalent
effect in air. Be that as it may, the receiving end of, say, a 200
decibel focused beam of HF sound would not be a fun place to be. Of
course it'll still fall off as 1/n^2 but the "n" won't be distance from
the source if it's well focused. Rather, if distance to the source is
"r" then I think you'll find the sound should fall off as something like
1/(r+K)^2 for some positive constant K.
