archiv~1: Re: SETI Arecibo message to m13

Re: SETI Arecibo message to m13

Alfred A. Aburto Jr. ( (no email) )
Mon, 02 Nov 1998 20:28:08 -0800

Hello Nico,

I think the distance to M13 was known fairly accurately
by Drake when he transmitted from Arecibo. The coded
message was a little under 3 minutes long and it will
take 24,000 years or so to reach M13 ...

The problems I think you are addressing are:
"when in time to look, how long to look, where in space
to look, where in frequency to look, and with how much
sensitivity"?

These are big problems, not easily solved!

Imagine an intelligent technological civilization like
ourselves on a planet orbiting some star in the M13
cluster. What chances would you give them in detecting
Dr. Drake's message? Very slim I'd say because they would
need to be looking at the right time (!), the right 3
minutes in a time span covering, say, several billion
years of time, the right spot in the sky(!), at the right
frequency band, and with a large radio telescope having
significant sensitivity! The odds of detection would be
very miniscule I'd say ...

The SETI Institute has decided to examine 1000 sunlike
stars within approximately 200 light years of Earth. They
are looking for any kind of interesting activity in the
neighborhood of these stars (not just a beacon but any
sign or evidence whatsoever). Using the worlds largest
radio telescopes they have alot of sensitivity (able to
detect very weak emissions) and one would suspect that
eventually something interesting (and exciting!) would
pop up.

Or would it? The probability of detection depends upon
many factors. If the density of technological civilizations
at our level or above is high in our Galaxy then "when one
looks", "how long one looks", and "where one looks" is not
so important. All one would need to do is look and they will
be found! This could in fact be the case, and discovery or
contact is "just down the road a bit", but we need to look!

If however the density of ETI (technologically advanced
civilizations) is low (say 10,000 or less in the Galaxy)
then the problem becomes much more difficult. One could
search for thousands of years and not find anything!

One strategy (since we really want to know if anyone else
is out there) is to assume that there are a few ETI out
there that really want to communicate and they will
transmit with enough power that sensitivity of the receive
antenna is not an issue (small antennas will suffice). The
only problems then to achieve detection is to provide
"all sky" and "continuous" monitoring. The SETI League
is working to accomplish this. The only other major problem
is frequency coverage (our frequency bandwidth must be
greatly increased).

You know what bothers me most? It is the super civilizations.
Civilizations who are vast users of power (thousands to
possibly billions of years ahead of us). Where are they?
They should be easily detectable!! But there is no sign of
them. Not the slightest clue or hint has popped up after
many years of optical and radio observations of our Galaxy
(observations actually throughout the electromagnetic
spectrum)! Nothing, except perhaps the Universe itself, to
make us suspicious that there is any one else out there.
Perhaps there is really no one else out there, or perhaps
we have big and profound things to learn in the future ...

Al Aburto

> "Nico L." wrote:
>
> Hi,
>
> I'm debating with my friends about the possibility to send
> a radio message far from here.
> We know that limitation is light speed, so if I say that m13 is about
> 24 thousand light years from here or Proxima Centauri is about 4 years light,
> I know the an approximate value of this quantities as distance values...
> When Carl Sagan and Frank Drake sent message towards Arecibo,
> I think that we don't know the exact position of the globular cluster,
> we can only think that waves are a spherical form and every direction
> is similar to another one.
> Has a sense to point a radiotelescope to m13 and send a message
> if we do not the exact position on the sky ?
> When we point a radiosource we can hear the radio source and we are right
> to point the position of the source because we are receiving light and radio pulses,
> but what happens if radiosource started to send pulses later or a period later
> than the source light or viceversa ?
>
> thanks in advance
> Nico Lonetti - Italy
>
> - Nico Lonetti mailto:orbiter@tin.it - Cosenza - Italy -
> | AOL instant message: NicoLonNic |
> --------------------------------------------------------
> Italy, Time zone: GMT + 1
> Alt. 225 m +39.322 Latitude -16.216 Longitude
> --------------------------------------------------------
> mIRC: #astronomy, #astronomia
> 198.187.154.237:6667 #seti, Nick: NicoL
> --------------------------------------------------------
> G.A.M. - Gruppo Astrofili Menkalinan -
> http://www.geocities.com/Area51/Dimension/5189/gam.htm