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From: Mark Isaak <specimenNOSPAM@curioustaxon.omy.net>
Newsgroups: talk.origins
Subject: Re: New SETI search
Date: Mon, 2 Sep 2024 18:22:56 -0700
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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?

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.

-- 
Mark Isaak
"Wisdom begins when you discover the difference between 'That
doesn't make sense' and 'I don't understand.'" - Mary Doria Russell