EJASA - Part 2

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                                   PREFACE

        This paper is about the Search For Extraterrestrial Intelligence
    (SETI) in the Optical Spectrum.  It is a revisit of suggestions which
    for various reasons have yet to be accepted by the majority of the
    SETI community.  This document does not address the usual controversial
    aspects about SETI, such as Fermi's Paradox, i.e., "Where are they?"
    and the arguments of Frank Tipler. [20,39]  We shall also not discuss
    exotic forms of radiation, such as X-rays, gamma rays, neutrinos, and
    gravitational waves.  This paper deals primarily with the superiority
    of interstellar optical beamed communications over their microwave
    counterparts.

        In general, the concept of SETI is "sold" on the basis that
    electromagnetic waves are the cheapest (in energy cost) and fastest
    way to travel through deep space, and is the next best thing to
    actually being there.  I tend to believe that interstellar travel by
    humans will be quite commonplace in the centuries to come, so that
    for myself there is the paradox (Kingsley's Paradox) of why
    communicate when it is possible to travel?

        It is perhaps useful to state from the start what are my basic
    beliefs, with the caveat that there is presently very little scientific
    evidence to support any of these speculative ideas.

    (a)  The universe is literally crawling with life, some of this extra-
         terrestrial life being highly intelligent.

    (b)  In general, extraterrestrials do not stay at home, but they do not
         leave the exploration and colonization of the galaxy to self-
         replicating von Neumann probes. [20]

    (c)  Extraterrestrials find it easy to travel across the galaxy in
         near-relativistic or relativistic spaceships.

    (d)  On the basis of (a), (b) and (c), it is likely that at least some
         of the so-called sightings of Unidentified Flying Objects (UFOs)
         do in fact relate to visitations from other worlds, and that
         Earth's history and the evolution of life on this planet may have
         been affected by such visits.

    (e)  If (c) is not possible and von Neumann probes are not employed,
         then electromagnetic waves could be used by extraterrestrial
         civilizations to contact their counterparts in other stellar
         systems, particularly more primitive technological civilizations.

    (f)  If (e) is occurring, then it is more likely that the optical
         region of the electromagnetic spectrum would be used, in
         preference to the microwave region.


        Note that there is of course, the possibility of radio or optical
    communications from von Neumann probes in our vicinity, both with us
    and with their home worlds.  Perhaps the greatest difficulty that I


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    have with electromagnetic SETI is my long-held belief in what has come
    to be known as the "Cosmic Zoo", which is related to idea (c).  If we
    are indeed presently off-limits for "Contact" in any form, i.e.,
    quarantined, searching for electromagnetic signals would be a waste of
    time, never mind the consideration as to whether there are a sufficient
    number of ETIs in the galaxy to make electromagnetic "Contact"
    probable.  However, this study is restrictive in its terms of
    reference, as it only considers the relative efficacies of the
    microwave and optical approaches to electromagnetic SETI (f).  For the
    sake of this discussion, we shall not make much of an attempt to
    resolve these other problems here.

        I would, however, make some observations.  It has been a long and
    somewhat difficult road for SETI researchers to establish electro-
    magnetic SETI as a legitimate science.  To some extent, for political
    reasons, they have had to strongly disassociate themselves from those
    who believe in UFOs.  This somewhat artificial differentiation has been
    done to reduce the incidence of being labelled "crazy" by their more
    conservative colleagues and Members of Congress, and to maintain the
    rationale that electromagnetic interstellar communications is the
    cheapest form of travel.

        In reality, there is more common-ground between scientists who
    believe in UFOs and those that ascribe to SETI, than the latter might
    care to admit.  To maintain otherwise is being intellectually
    dishonest, for both believe in "Aliens" or what are now more affection-
    ately referred to as "Extraterrestrials" (ETs).  In the end, what one
    believes (as against what one knows and is scientifically proven) comes
    down to imagination, or the lack of.  On the other hand, what one
    publicly admits to believing is quite another matter entirely.  This
    involves other more down-to-earth considerations, like the fear of
    being ridiculed by colleagues and the scientific establishment.

        One only has to remember how the "keepers of the flame" recently
    reacted to the Cold Fusion work of Martin Fleischmann and Stanley Pons,
    to realize that the scientific establishment does not take too kindly
    to those would dare to "rock the boat" of conventional orthodoxy.
    Fortunately, the theory on Optical SETI given in Appendix A is based
    on long-established scientific principles, so this author should fare
    somewhat better.

        Three types of civilizations have been postulated by Kardashev for
    the development of "super civilizations". [4,13,25]  A "Type I"
    civilization would be in a similar stage of development as Earth,
    having gained control of most of the energy sources on the planet of
    origin (about 4 X 10^12 W).  A "Type II" civilization would have
    reached a level at which it controlled the energy output of its own sun
    (4 X 10^26 W).  A "Type III" civilization would have gained control of
    the energy output of the entire galaxy (about 4 X 10^37 W).

        This paper really addresses the type of technology and energy
    sources available to Type I and Type II civilizations.  Freeman Dyson
    has described how a Type II civilization might dismantle one of the
    larger planets in its solar system and build a shell completely


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    surrounding its sun. [25]  A Type III civilization would hardly need to
    use microwave or optical technology for communications, and might
    consider us little more than we do ants.

        During the past eighteen months, I have been associated with
    Dr. Robert Dixon's SETI Group at Ohio State, and have had extensive
    communications with the SETI Institute at NASA's Ames Research Center
    in Moffett Field, California.  My approach in revisiting this subject
    has not been the conventional one of publishing a paper or papers and
    waiting for the "penny to drop".  Rather, because several noted
    researchers have published papers along similar lines over the past
    thirty years and have largely had their ideas rejected by their
    colleagues, I decided to try a somewhat different strategy:  To take
    the SETI community by storm.  The reader is assured that to the best of
    my knowledge, no laws of physics have been violated in this study.
    What is true, however, is that the human imagination has been stretched.

        This is not the first time, nor will it be the last, that the
    scientific community may have gone in the wrong direction because of
    mistaken assumptions.  What I am doing is to seriously question
    present SETI lore, with due respects to Professors Philip Morrison,
    Frank Drake (President, SETI Institute), Carl Sagan, Dr. Bernard Oliver
    and the late I. Shklovskii, to name but a few.  At first glance, the
    three decades old idea that ETI signals will be found in the quietest
    region of the electromagnetic spectrum seems reasonable.  Thus, the
    21-centimeter hydrogen (H) line and the region of the microwave
    spectrum between the H and lowest OH resonance lines (1.420 to
    1.662 GHz), which has come to be known as the "waterhole", has become a
    favored "magic frequency".  However, we may have been too clever by
    half in guessing the natural interstellar communication frequencies,
    and in assuming that ETIs will make it very easy for us to locate their
    signals.  Perhaps our commitment to the search for ETI must be
    substantially increased before we are rewarded by success.

        Over the years, many science fiction writers have involved inter-
    stellar laser communications in their story lines.  Indeed, in the 1990
    SETI book, FIRST CONTACT [26], edited by Ben Bova and Byron Preiss, Ben
    Bova wrote a story involving Optical SETI called "Answer, Please,
    Answer".  Interestingly, a recent edition of NEW SCIENTIST [45] which
    had an article about SETI, also contained a review of the new paperback
    issue of FIRST CONTACT and criticized it, suggesting that it was
    inappropriate to include this science fiction material.  However, there
    may have been more truth in that story than in much of the rest of the
    book.  Perhaps it is time again for scientists to take note of what
    science fiction writers have to say!

        FIRST CONTACT also contains a chapter (Chapter 9, "How to
    Participate in SETI", by Kent Cullers and William Alschuler) devoted to
    Amateur Microwave SETI, but it is not clear how many TVRO (TeleVision
    Receive Only) owners would wish to convert their satellite dishes for
    this purpose.  In the microwave regime, amateurs would be competing
    with the "big boys", but in the optical regime they would be essent-
    ially on their own.  The contribution that the amateur optical
    astronomy enthusiast can make in this area is described later.


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        What I do find slightly disturbing is that the popular literature
    on SETI usually says either nothing about the optical approach or
    dismisses it in a paragraph or two as being without merit.  As far as
    I can recall, THE PLANETARY REPORT [17,21,37] has never discussed this
    approach.  Even the latest PLANETARY REPORT article by Professor Paul
    Horowitz [37] fails again to mention the optical approach.  Indeed, the
    Planetary Society has just launched an appeal with the help of film
    producer and director Steven Spielberg, to raise funds for support of
    the Harvard BETA (Billion-channel Extraterrestrial Assay) project.
    This system will eventually have six billion channels and is designed
    to have a channel resolution of 0.05 Hz.  This trend in Microwave SETI
    channel resolution is directly opposite to the thrust of the Optical
    SETI rationale described herein, where minimum channel bandwidths of
    about 100 kHz are specified.

        Also, there appears to be misleading information in SETI books as
    to the visibility of electronically detectable signals and the efficacy
    of using Fraunhofer lines to increase signal contrast.  It is almost as
    if no one had bothered to "crunch" the numbers properly.  The fact that
    Fraunhofer lines have been previously thought to have a significant
    bearing on transmission frequencies in the visible regime, really
    arises from the assumption that ETIs lack the technical prowess to send
    us more than a few photons per second.  Once that assumption is swept
    away, the increased contrast ratio produced by these stellar absorption
    lines become less significant, particularly in relation to the use of
    optical heterodyne receiving systems. [71-73]

        Microwave SETI researchers are looking for very weak narrow-band
    signals buried in noise, and require the use of signal processing
    algorithms like the Karhunen-Loeve Transform (KLT) presently being
    studied by Dr. Robert Dixon's SETI group at Ohio State [73,86].  The
    KLT is more effective than the Fast Fourier Transform (FFT) in
    extracting non-repetitive pulses from noise-like data.  I assume, that
    Optical SETI signals will be much stronger and of substantially
    increased bandwidth, and may not need to be processed in this manner.

        The ten-year duration, 100 million-dollar Microwave Observing
    Project (MOP) now just starting, dramatically extends the search space
    in the Microwave Cosmic Haystack. [40-45]  As far as Visible Optical
    SETI is concerned, it would appear that scientists of the former Soviet
    Union have done most of the work in this area, though it represents but
    a tiny fraction of global modern-day SETI activities.

        If we confine ourselves to Visible Optical SETI for the moment, I
    make the following case that the sort of visible signal intensities
    which would allow modest-size telescopes to produce low-noise signals
    in moderate bandwidths are so weak that they would be easily missed by
    conventional optical astronomers.  One just has to remember, that for
    over thirty years, SETI researchers have been scanning the skies for
    artificial extraterrestrial microwave signals in a systematic manner.
    So far they have failed to detect a confirmed artificial extra-
    terrestrial signal.  What is the probability if such rare signals exist
    in the visible or near-infrared spectrum that optical astronomers
    would have accidently stumbled across them?


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        In early 1991, after "suggesting" that the SETI community should
    revisit the optical approach, I was invited to give a talk at the SETI
    Institute.  This Optical SETI Revisited Colloquium took place in April
    of 1991.  Prior to my NASA visit, I had concentrated my analysis on
    Professional Optical SETI and had given some thought to the optical
    equivalent of the Microwave Observing Project.  Some of the signal
    processing ideas arising out of MOP will be transferable to the optical
    search.  I was well-received by NASA, though there are certain members
    of the group who still hold to the view that the optical approach is
    useless, particularly at the high-frequency visible end of the
    spectrum.  After my talk, Dr. John Billingham, Chief of NASA's SETI
    Office, invited me to present a paper at the Commission 51 Bioastronomy
    Conference of the IAU (International Astronomical Union), which is to
    be held in 1993, and have that paper printed in the journal ACTA
    ASTRONAUTICA.

        In recent years, NASA has supported a limited activity in SETI at
    10,600 nm.  However, its main thrust has always been Microwave SETI.
    For about five years, NASA has been supporting Charles Townes and
    Albert Betz in a low-level activity at the Carbon Dioxide (CO2) laser
    wavelength.  This work has been "piggy-backed" onto a larger program
    for CO2 astrophysical research.  They are using an interferometric
    system consisting of two infrared telescopes mounted on a trailer, with
    two phase-locked heterodyning CO2 local-oscillator lasers, nitrogen-
    cooled photodetectors, and a bandwidth of a few MHz.  The observations
    are being conducted at Mount Wilson Observatory.  The SETI aspect of
    this work is so low-key that I found some difficulty in obtaining
    details about this activity.

        Over the early part of the summer of 1991 while I was back home in
    England, I was able to convince myself that perhaps the concept of
    Amateur (visible and near-infrared) Optical SETI was not such an
    implausible idea.  Over the past eighteen months, I have undertaken a
    substantial self-funded analysis of Professional and Amateur Optical
    SETI, of which this represents a brief summary.  I would be interested
    in hearing from any major space/astronomy publication or organization
    that would like to approach me for an article, book, or talk, or any
    company which might be interested in a business relationship in this
    area.  I have prepared a substantial illustrated viewgraph report on
    this subject, which the few ASCII text diagrams and graphs in this
    document can hardly do justice.  I would be interested in producing an
    Optical SETI book accompanied with compiled versions of many of the
    spreadsheets that I have employed for these analyses.  This would allow
    readers to do their own "what-if" analyses.

        The SETI Institute and NASA have been alerted that I will be going
    public about Professional and Amateur Optical SETI at this time,
    because of my gut feeling that there will be a surge of interest in
    this subject seldom seen during the thirty years of modern-day SETI.
    NASA might like to consider coordinating world-wide Amateur Optical
    SETI activities to avoid excessive duplication of searches on the same
    target stars.  This would also present the opportunity to compare data
    to that obtained for the same stars with the Microwave Observing
    Project.


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        After digesting this material, some readers are bound to feel that
    what they have read they always knew, but were intimidated by the
    giants of the scientific community.  Perhaps there is no field of human
    endeavor like SETI which involves so much speculation, where the
    citizen with a scientific background is just as qualified to speculate
    as the professional SETI scientist.  The controversy over this approach
    is bound to rage for some time.  Soon after I embarked on this study in
    June of 1990, I came to the conclusion that if this revisit of Optical
    SETI was to at last be given the attention it deserved, I would have to
    take a very different approach to getting the material published.

        It is fitting that this first publication of these ideas is being
    done via the electronic media, the computer networks which span the
    globe.  It has been advantageous that it has also given me substantial
    space in which to delineate the full scope of my rationale in one go,
    without leaving too many gaps.  Indeed, what started out as a small
    paper has turned into a mini-book.  Who knows; perhaps ETIs in the
    future will intercept signal leakage from Earth's microwave satellite
    uplinks, read this document, or eavesdrop on terrestrial TV and radio
    transmissions, and have a chuckle (I assume that humor is more than a
    human trait):  "Those crazy humans, if only they knew!".

        During the early formative part of my life, I owned a small
    refracting telescope and would spend many hours studying Earth's moon
    and the planets.  It has been a long time since I possessed another
    telescope.  Because I believe in putting my money where my mouth is, I
    am now impatient to put together my own Amateur Optical SETI
    Observatory.  This paper has yet to be peer reviewed and the author is
    solely responsible for its contents.  Readers are encouraged to check
    out the relationships used and the accuracy of the calculations.  The
    rest is then a matter of opinion and imagination.

        Optical SETI investigations will probably take a lot of
    perseverance.  In the grand tradition of American disclaimers, readers
    should note that I cannot accept responsibility for the lack of success
    in detecting ETI - ("Caveat emptor"!).  Since I expect that there will
    be considerable reaction to this material, I therefore beg your
    indulgence if I do not presently reply or reply in detail to every
    personal message received in response, either by conventional mail,
    fax, or network E-mail.  However, a personal response is assured
    through my own bulletin board system (BBS), which has been set up
    specifically to coordinate future world-wide Optical SETI activities.

        Simultaneously with the electronic publication of this document, I
    have established a BBS devoted to SETI in general, and Optical SETI in
    particular.  More modem lines may be added later as interest warrants.
    The telephone number is (614) 258-1710 and supports all modem speeds
    up to 9600 baud.  The BBS is dedicated to NASA and the late Gene
    Roddenbery, the latter having had a substantial influence on how I view
    the future.  Many of the spreadsheets, diagrams and graphs - and there
    are many - that have supported the development of my rational, will
    eventually be made available via the bulletin board.  For further
    details about this computer bulletin board, see the BBS information
    (Page ii) at the front.


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        The theoretical justification for the results and conclusions
    drawn in this paper has been relegated to Appendix A.  In this way,
    those readers uncomfortable with scientific theory and mathematical
    relationships do not have to have wade through masses of equations.
    It is, of course, very difficult to be everything to all people.  For
    this reason, I have compromised in this approach by keeping the theory
    as simple as possible, and have avoided the use of statistical analysis
    and calculus.  For instance, the way that the signal-to-noise ratio of
    a detected optical signal varies with received photon flux, bandwidth,
    and signal integration time is exceedingly complex when the photon flux
    is weak, particularly if avalanche photodetectors are employed.  There
    will be plenty of time later for this author and others to present a
    more rigorous approach to Optical SETI.  This can be done in a variety
    of learned journals, such as IEEE's LIGHTWAVE TECHNOLOGY and
    TRANSACTIONS ON COMMUNICATIONS, or the IEE's ELECTRONICS LETTERS.

        The purpose of this document is to rekindle the debate between
    those who believe in the microwave approach to SETI and those who
    subscribe to the efficacy of the optical approach.  An additional
    desire is to introduce my colleagues in the fiber-optics field to a
    rather exciting concept - an idea which dwarfs all the puny terrene
    "hero" long-distance demonstrations that large fiber-optics
    communication companies like to brag about from time to time.  As
    actor Al Jolson used to say, "You ain't seen nothing yet!".

        I would like to acknowledge discussions and encouragement from
    various sources:  Dr. Robert Dixon (Director, SETI Program) for a very
    professional reaction to what I had to say, despite having devoted
    decades of his SETI activities to the microwave search with "Big Ear".
    I also acknowledge Dr. Dixon's contribution in being given access to
    the educational and scientific network.  In addition, I would like to
    thank Professor Charles Townes (University of California, Berkeley) for
    his helpful comments when this study was first started, recent E-mail
    discussions with his colleague Dr. Albert Betz, Professor Philip
    Morrison (MIT), and correspondence with Dr. John Rather (NASA-HQ).

        I would also acknowledge correspondence and discussions with
    Dr. Bernard Oliver, who in early November of 1990 sent me a copy of his
    Cyclops report, convinced that it would prove the case for the efficacy
    of the microwave approach.  In my correspondence and discussions with
    Dr. Oliver, who is also known as the "grand old man" of SETI, I have
    not been able to shake his belief in the correctness of the microwave
    approach.  So we have agreed to disagree over the relative merits of
    Microwave and Optical SETI.

        Over much of the past year and a half while the ideas were
    developing, I have interfaced with parts of the SETI community.  There
    is some perception that my "lobbying" for the optical approach to SETI
    may already have had some effect on how those within NASA and the SETI
    Institute now view Optical SETI.  At least, I have received rather
    "mixed signals" over the past eighteen months as to where the consensus
    lies, and there appears to have been some shift towards my position,
    though this may be a presumption on my part.



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        I would particularly like to acknowledge the professional courtesy
    and assistance given me by Dr. Jill Tarter (NASA SETI MOP Project, SETI
    Institute, U.C. Berkeley) and her staff at the SETI Institute, despite
    the fact that I may have "come on quite strong" in revisiting Optical
    SETI.  I also thank Dr. Kent Cullers (Signal Detection Scientist, NASA)
    then of the SETI Institute, for his encouragement and for checking some
    of my calculations relating to Professional Optical SETI.  I trust he
    will do the same, if he can draw himself away from MOP for a few
    hours, for my more recent computations relating to Amateur Optical
    SETI.

        Finally, I must acknowledge the considerable assistance of the SETI
    Institute's Robert Arnold (Research Assistant and Public Information)
    in providing me with much background information on SETI.  I hope I do
    not give him too much of a headache when he has to deal with the surge
    in national and international interest in all forms of SETI which will
    probably result from this paper.  It is highly likely that because of
    the Microwave Observing Project and this paper, 1992 is going to be the
    Year of SETI.

    Dr. Stuart A. Kingsley
    Columbus, Ohio
    December 24, 1991

Continued