Re: New SETI search

On 8/27/2024 2:11 AM, Ernest Major wrote:

On 27/08/2024 06:24, El Kabong wrote:

Previous searches at Aricebo and other sites looked for
alien signals at 1420 Mhz.  They picked that frequency
because it is a hydrogen line.  The thinking is that
aliens would more likely broadcast there than an
arbitrary frequency.  It never made sense to me because
the signal will be attenuated by any hydrogen lying in
the path, and because if you tune in to the hydrogen
line, you'll find... hydrogen noise!

 The argument is that the 1420 MHz line is less arbitrary, and is not absorbed by interstellar dust.
 

If the aliens had broadcast at 1420 MHz what would be the frequency that we would detect in an expanding universe?  I realize that some galaxies are moving towards us, but the red shift indicates that most things are getting further away from us in all directions due to the Big Bang.
Ron Okimoto