archive: Re: SETI A hair-brained idea

Re: SETI A hair-brained idea

Peter Coffee ( pcc_csm@earthlink.net )
Thu, 17 Sep 1998 12:13:07 -0700

Colin Crook wrote:
>
> ...light is a form of radiation. So are radio waves...

True, but the wavelength of (what we call) a radio wave is many orders
of magnitude longer than that of (what we call) a light wave.

Think about the aperture that you need to get useful resolution of
images when the wavelengths are in the hundreds of billionths of a meter
(what we call "visible" light).

Scale up to the aperture that's required to have corresponding
resolution when the wavelengths are in the millimeters, centimeters, or
longer.

Visualize the size of the Arecibo dish. This is why radio telescopes
have to be so gosh darn big.