Introduction for OSETI I
Within these pages you will read contributions from some of the top researchers involved with the electromagnetic search for extraterrestrial intelligence, otherwise known as SETI. You will also read about the controversy of whether most of this planet's SETI receivers are tuned to the correct frequency regime. This conference revisited an approach to SETI first suggested 32 years ago by Nobel laureate Professor Charles H. Townes.
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 Paradox) of "Why communicate when it is possible to travel?". Nevertheless, despite this and the well-known Fermi Paradox of "Where is everyone?", I consider SETI to be a worthwhile pursuit in the quest for knowledge; which exemplifies the best tradition in human exploration.
This conference marked the occasion of a number of firsts. For the first time, a conference had been organized largely devoted to the optical approach for SETI, otherwise denoted herein as OSETI. We will denote Conventional, or Microwave SETI by the acronym MSETI. Professor Charles Townes has been most patient in waiting over three decades for this international conference - patience being the watchword for SETI researchers! It was the first time that Dr. Barney Oliver has had the opportunity to present his case to laser and electro-optic specialists, as to why ETs would not use lasers to contact emerging technical civilizations like ourselves. This conference was the first time that Professor Frank Tipler had met members of the SETI community and was able to present his case in closed-loop fashion, as to why SETI is a complete waste of time. It is believed that this Optical SETI meeting marked the first time that philosophers have participated in a SPIE conference. In addition, it may also hold some sort of record for being arranged at rather short notice.
A year ago, I was asked to put this meeting together by Dr. David Begley, the previous chairman for SPIE's free-space laser communication conferences. The meeting was originally envisaged as a special session within the free-space laser communications conference, but later evolved into a dedicated complementary conference. The request from SPIE to arrange this meeting came about as a result of a large technical article of mine about Optical SETI which appeared in the Electronic Journal of the Astronomical Society of the Atlantic (EJASA) and was published on the Internet in January 1992. Because of the close connection between the technologies of free-space laser communications and Optical SETI, Dr. Jim Lesh's laser comms paper on NASA's present laser communications activities has been reproduced here. As conference chairman, I was pleased by the size of the audience for the first session, which must have numbered about two hundred. Unfortunately, this level of interest wasn't maintained for the second and third sessions - a reflection of the problem of holding a conference in California at the end of the week!
For the purposes of the scientific activity called OSETI, I wish to define the word "optical" as being the superset description for that part of the electromagnetic spectrum lying between the ultra-violet and far-infrared regimes. The word is not to be taken as being synonymous with the word "visible". Both Visible and Infrared SETI are subsets of Optical SETI. This conforms to the modern definition of the word "optical", as used every day throughout the world by optoelectronic (photonic) engineers and scientists. This modern definition may cause some pain for astronomers and physicists, but will avoid needless confusion later.
At this point, I would like to present here a modified form of the famous Drake Equation:
N = R x fs x fp x ne x fl x fi x fc x fo x L
N = Number of civilizations in our galaxy trying to make contact for which we are using suitable receivers.
R = Average rate of star formation (10 per year).
fs = Fraction of stars that are "good" suns (0.1).
fp = Fraction of good stars with planetary systems (0.5).
ne = Number of planets per star that are earth-like (1).
fl = Fraction of earth-like planets on which life develops (0.1).
fi = Fraction of earth-like planets where life becomes intelligent (0.01).
fc = Fraction of intelligent species who want to communicate in space (0.1).
fo = Fraction of communicating intelligent species who prefer to communicate by optical means, i.e., via lasers (0.80).
L = Lifetime of this civilized phase (108 years).
Here, the new definition of "N" is now the number of civilizations in our galaxy trying to make contact with electromagnetic devices to which we have matched receiving systems. If we use microwave receivers to listen for ETI signals and most ETIs use lasers, then clearly N tends to zero. This conference is really about maximizing "N", which for the above assumptions comes to 4,000 (assuming sufficient transmitter power and receiver sensitivity). Other SETI researchers have projected far higher values for "N" - values approaching the one million level.
I have assumed somewhat arbitrarily, that 80% of ETIs use lasers, either in the visible or infrared, 1% use gamma or x-rays, and that 8% of such civilizations use some non-electromagnetic means that we have yet to discover. Because of the Kingsley Paradox of "Why communicate when it is possible to travel?", a 10% factor is allowed for ETIs who would rather travel than transmit, and have the capability to do so. The remaining 1% use microwaves! Because of my own optimistic views that in time mankind will eventually develop the means to "whiz" about the galaxy, it should not be surprising that I consider the process of aiming tight high-intensity beams into nearby stars, as being relatively trivial for a mature technological society.
Note, that the above probabilities represent my prejudices at this time. It should not be taken to indicate that I am in anyway against MSETI, rather that OSETI has suffered over 30 years of relative neglect, and we need to redress the balance. It was clearly sensible to start with MSETI, but optical technologies are now sufficiently mature that major OSETI research programs should be launched. When all is said and done, the main reason why free-space laser communications have not been considered the best technology for SETI, has been that their main advantage of extremely high EIRPs has been thrown away by severely limiting the maximum aperture sizes of optical ETI uplinks. This has put the onus on the us, the primitive technological civilization, to construct unnecessarily large and expensive downlink receiving telescopes. In essence, the argument really boils down to what one believes is the knowledge-base and targeting capabilities of an advanced technical civilization, i.e., that of ETIs. The reason why these poor assumptions were made some twenty years ago will become clearer as you read the conference papers.
I am indebted to Arthur C. Clarke for being a gracious and enthusiastic participate in this conference as the keynote speaker. This gave me the opportunity to renew our acquaintance which was formed some twenty years earlier at the Astronomical Society of Haringey (ASH) in London, England. It was my delight to meet the distinguished speakers, many for the first time, particularly Professor Charles Townes, who did a fine job in moderating the panel discussion. My only regret was that as conference chairman, I was too busy to have one-on-one conversations with most of the speakers.
I am grateful to Dr. Michael Klein for arranging the HRMS display that was set up outside the conference room. My thanks go to Angelo Campanella, a volunteer with the Ohio State University (OSU) SETI Group, for assisting in the transcription of the panel discussion, and to Professor Neil Tennant (OSU) for at short-notice, proof-reading the material over the Internet. Other thanks go to Dr. Robert Dixon (OSU) and Professor John Midwinter (my alma mater, University College London), for access to the Internet on both sides of the Pond. I also acknowledge the considerable assistance over several years, of the SETI Institute's Robert Arnold, and thank Larry Klaes, editor of the EJASA, for giving me the opportunity to espouse my OSETI views over the Internet. It is clear to me that Dr. John Billingham, Chief of NASA's SETI Office, has been of considerable assistance in making sure that we had the participation of his top people, and as a result, a more interesting conference. For this I am deeply grateful. I would also like to thank my co-chair Monte Ross for some "illuminating" ideas, and for having pointed out the benefits of pulsed techniques for interstellar communications many years ago. Finally, appreciation goes to Clive Goodall for livening up the panel discussion by remaining on the floor.
Towards the end of the conference, Dr. Michael Klein, who heads JPL's "All Sky Survey", expressed concern that Amateur Optical SETI (AMOSETI) might lead to NASA losing control of SETI, and be the cause of generating spurious claims of ETI detection. However, considering the price of the entrance ticket for AMOSETI, and that as it catches on it would become self-policing (refereeing), the amount of "static" so generated should be minimal. In that regard, the reader's attention is drawn to the special appendix at the back of the proceedings that contains a copy of "The SETI Protocols". The appendix gives the procedures to be followed should you discover ETI signals. One of the reasons for setting up a computer bulletin board system (BBS) in 1991, was to help organize future professional and amateur Optical SETI activities, particularly with regard to a coordinated world-wide amateur optical targeted search. It would not be too surprising, if through serendipity, that while AMOSETI enthusiasts search for fast pulsed ETI beacons, they will happen to discover high speed natural phenomena, not previously predicated by optical (visible) astronomers.
For this and other concerns, the reader is most welcome to contact me at the address below. The six-part, 138-page January 1992 EJASA (Volume 3, Number 6) article on OSETI which led to this conference may be downloaded from my BBS (EJASA306.ZIP), from the Space & Astronomy Forums on CompuServe (EJASA.ZIP) or from the Internet via anonymous ftp at chara.gsu.edu (184.108.40.206), directory: /pub/ejasa. Alternatively, you may contact the EJASA editor Larry Klaes at email@example.com to request a copy. PC and Mac-compatible diskettes containing this article are available from the conference chairman for those without Internet and/or modem facilities.
I look forward to the day when OSETI becomes a part, nay a significant part, of NASA's High Resolution Microwave Survey (HRMS) Project, and we then go on to discover the interstellar optical equivalent of Internet! Perhaps NASA's SETI program will be renamed again; this time the "High Resolution Microwave & Optical Survey (HRMOS)". In conclusion, I hope that within these pages you find much food for thought.
Dr. Stuart A. Kingsley
Tel: (614) 258-7402
Copyright (c), 1993, SPIE