Re: New SETI search

On Tue, 3 Sep 2024 21:48:53 +0200, the following appeared in
talk.origins, posted by nospam@de-ster.demon.nl (J. J.
Lodder):

Mark Isaak <specimenNOSPAM@curioustaxon.omy.net> wrote:
>

On 8/26/24 10:24 PM, El Kabong wrote:

RonO wrote:
 

A group is using the Murchison wide field array to monitor for super
civilizations in other galaxies.  The civilizations would have to be
super advanced in order to generate the 100 MHz signal that they are
scanning for.  Huge amounts of energy would have to be channeled into
transmission of such signals.  Would we ever expend such an effort to
tell someone in another galaxy that we exist?  100 MHz is in the middle
of the FM radio band, but in our expanding universe what would have been
the frequency transmitted by any one of the 2,800 galaxies scanned in
the survey?
>
https://www.sciencedaily.com/releases/2024/08/240826131354.htm
>
Ron Okimoto

 
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!
 
Maybe space aliens will broadcast on 100 Mhz because it's
a nice round number?  Then again they might have 3 digits
per hand and use a base-6 system and think 60.466176 Mhz
is a nice round number where other hexadigits would
listen.  In any case you have to pick a frequency
somewhere.
 
The article you cited does link to an article on a
previous survey done in 2020, but it doesn't mention the
frequency.
 
If the aliens transmit from a large phased array like
MWA, they could transmit a large effective power within
the beamwidth, without actually transmitting huge power.
But the beam has to be aimed in our direction.  Maybe
they send signals periodically in every direction.
Similarly the MWA has to have its array pointed in the
right direction at the right time.
 
The chances are slim, but worth trying.

 
If I had vast technological resources and wanted to send an "I'm here"
signal to unknown aliens over potentially vast distances, I wouldn't
generate light. That would take way too much energy, especially if it
was broadcast widely. Instead, I would rig up some opaque sheets and set
them orbiting around a star, with gaps in places so that anyone watching
from the plane of orbit would see a dit-dah message spelled out
repeating every 6 (of our) months or so.  It would work only on a fairly
narrow plane, but at least it's better than a laser pointed at a single
target.
 
Is SETI set up to look for anything like that?

>
Why would they waste resources on that?
Any search for exoplanets will find such a signal.
As a matter of fact somthing very much like it has already been found.
(six planets around the star HD 110067
locked in periodic perfect 3/2 and 4/3 resonances)
No design involved.
>

True. But one could make it arbitrarily complex, with
essentially zero probability of it being natural.

>

Of course, I would never do anything to attract strangers until I was
more than confidence that my technology could overpower any hostile
aliens I might attract. If possible, I would set up the signal several
hundred light-years away from concentrations of my species' population.

>
You are American, I presume?
>

Why do you assume that?

>

--

Bob C.

"The most exciting phrase to hear in science,
 the one that heralds new discoveries, is not
 'Eureka!' but 'That's funny...'"

- Isaac Asimov