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Optical SETI Survey - Introduction (Part A)

Radobs 7A

 
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                      "Where no photon has gone before?"

To all members of OSU's RADOBS bulletin board from Stuart Kingsley:
Version 1.0
                
I thought I would go through the exercise of listing (delineating) many of
the areas I have investigated in my Optical SETI study, and my rationale. 
In order to make it easier for RADOBS members to read, digest and download
this Survey, it has been split into seven roughly equal parts, which will be
sequentially uploaded over the Christmas/New Year period.  Each statement or
question is concluded with a YES or NO response.  Print out each part and
circle your responses - it should be very revealing!  I would appreciate
receiving your comments and scores through email, through the post, or
hearing about them by phone.  Do not respond with your scores until the
complete Survey is posted on RADOBS, as you may wish to go back and revise
your earlier responses.  A form is provided at the end of Part G to
facilitate responding by mail or email.  Hopefully, this series of
communications should initiate a lively debate on RADOBS as to the merits of
the optical approach to SETI, a critique of my rationale, and contributions
from others to add to the Optical SETI rationale delineated herein.
I have believed for several decades that the universe is crawling with
intelligent life, particularly, as even the Milky Way Galaxy alone is
thought to contain 400 billion stars, and there are more galaxies in the
universe than stars in our galaxy.  As you are reading this introductory
message, you obviously don't need to be convinced about the merits of the
"search".  I think that in time, mankind may well discover the means to take
short-cuts across the galaxy and may develop sub-space communication
techniques (ala Star-Trek) that overcome the limits of the speed of light. 
However, the latter is in the realms of science fiction.  From our present
state of knowledge, it would appear that in preference to physically
travelling over the vast distances of interstellar space, with corresponding
enormous expenditures of energy and time, electromagnetic radiation is the
cheapest form of travel, and is the next best thing to actually being there.
The Optical SETI rational delineated in the Survey, is based on science as
we know today, and a little imagination - admittedly somewhat
anthropocentric.  We assume that advanced technical civilizations (ATCs)
still use electromagnetic communication technology in a big way, and have
the desire to contact emerging technical civilizations (ETCs).  It is also
not out of the question that we might accidently intercept signals passing
our way and not meant for our ears or eyes!
The real issue here is what form of electromagnetic communication technology
would be used - on what type of photon would we hitch a ride?  Would it be
on microwave photons (radiation) which has the benefit of very low
interstellar background noise, or would it be on optical photons (far-
infrared to ultra-violet) that has the benefit of extremely high Effective
Isotropic Radiated Powers (EIRPs), and compact transmitting/receiving
antennas, but suffers from significant quantum noise.
I have never seen a field of science so flawed with misconceptions and half-
truths.  It is recognized that I will have to work very hard to convince the
SETI Community that much of what they have believed for the past 30 years is
in error.  Many of the so-called problems with Optical SETI, e.g., very high
Doppler shifts and drifts (chirp), have relatively simple technological
fixes.  I will let you be the best judge after you have worked through the
following statements and questions.  Even if you are not finally convinced
that the optical approach to SETI is the best, I feel confident that it will
be hard for you to escape the conclusion, that any serious SETI enthusiast
who avoids looking in the optical regime, substantially diminishes the
chance of the successful detection of Extraterrestrial Intelligence (ETI).
My Optical SETI study is mainly centered on space-based transmitting and
receiving systems.  Recent developments in ground-based adaptive telescope
technology using laser guide stars would appear to indicate that within a
few years, ground-based visible telescopes will be able achieve diffraction
limited performance equivalent to that of space-based systems.  This will
probably have a profound affect on ground-based astronomy, and Optical SETI.
Studies also indicate that Optical SETI is the one branch of optical
astronomy, save for solar astronomy, that can actually be done during the
day, under a clear blue sky.
Please note, as explained in an earlier message, that my definition of the
umbrella word "optical" is accordance with the popular optoelectronics or
photonics definition, i.e., it covers the wavelength range from ultra-violet
to far-infrared.  This corresponds to wavelengths from about 300 nm to more
than 30,000 nm.  The Carbon Dioxide laser, which has many lines between
9,000 and 11,000 nm, is one of the most efficient and coherent lasers in
existence, and CO2 is likely to be readily available to ETIs in their
planetary atmospheres.  Although the main Carbon Dioxide laser line of
10,600 nm (where there is an atmospheric window) would appear to be an
optical "magic wavelength", I think that in time we will probably identify
several "magic wavelengths" or their corresponding "magic frequencies" in
the visible spectrum.  Visible laser systems have the advantage of even
greater EIRPs, though some argue that their beamwidths can be too small,
making targeting very difficult.
Now read on for an adventure in imagination.  Discover for yourself the
probability that artificially-produced extraterrestrial optical photons have
been falling on the Earth for millennia.  The adventure begins . . . .
December 17, 1990
RADOBS.07A
BBOARD No. 273
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Dr. Stuart A. Kingsley                       Copyright (c), 1990        *
* AMIEE, SMIEEE                                                           *
* Consultant                            "Where No Photon Has Gone Before" *
*                                                   __________            *
* FIBERDYNE OPTOELECTRONICS                        /          \           *
* 545 Northview Drive                          ---   hf >> kT   ---       *
* Columbus, Ohio 43209                             \__________/           *
* United States                            ..    ..    ..    ..    ..     *
* Tel. (614) 258-7402                     .  .  .  .  .  .  .  .  .  .  . *
* skingsle@magnus.ircc.ohio-state.edu         ..    ..    ..    ..    ..  *
* CompuServe: 72376,3545                                                  *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

 

 

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