In talk.origins Charlie Siegrist <none.active@this.time.check.back.later> wrote:

On Sun, 17 Aug 2008 21:42:00 +0000, Paul J Gans wrote:

In talk.origins Charlie Siegrist
<none.active@this.time.check.back.later> wrote:

On Sat, 16 Aug 2008 19:31:07 +0000, Paul J Gans wrote:

Because the radio age *here* will last only about 200 years, if that.

I don't see why.  As fiber-optic communication spreads, microwave point-
to-point is tending to decrease, but cell phone and other personal radio
communication devices are proliferating at a strong rate.  What will
take the place of that, along with: shipboard radar and radio?  Personal
and professional GPS equipment?  Aircraft communication and landing
systems? Rush Limbaugh and Howard Stern?

Cell phone and similar devices are very low power and not at all apt to
be picked up very far away.

Possibly low power, but also ubiquitous.  Multiply power by quantity and 
you've got a lot of radiation.

Shipboard radar and the like are aimed and not much is broadcast widely
at all.

PI navigation radars are by definition a spherical radiation.  Granted, 
the antennas are designed to minimize radiation in the vertical 
direction, but that's been a mainstay of both directional and omni-
directional antenna design since the beginning.

For comparison check the power used to reach the landers on Mars, and
that's aimed stuff, not spread over a wide area.  And that gets you to
Mars.

A one-time, one-shot investment of power.  I don't see that radio is 
quitting any time soon.  The switch to digital television is not going to 
effect a reduction in the transmission of television, and satellite and 
cable television require an infrastructure that relies on microwave 
communication systems.  People are not in a rush to junk their car 
radios.  The nature of radio is changing, but radio is not going away.

Short term view.  I repeat:  radio has been around for aboutg 100
years now.  I give it another 100.  I could be on the low side by
a factor of 10 and my argument remains.

-- 
   --- Paul J. Gans