Serendip II is an automated system designed to perform a real time search for narrow band radio signals in the spectra of sources in a regularly scheduled, non-Seti, astronomical observing program. Because we expect Serendip II to run continuously without requiring dedicated observing time, we hope to survey a large portion of the sky at high sensitivity and low cost. Serendip II will compute the power spectrum using a 65,536 channel fast Fourier transform processor with a real time bandwidth of 128 KHz and 2 Hz per channel resolution. After searching for peaks in a 100 KHz portion of the radio telescope's IF band, Serendip II will move to the next 100 KHz portion using a programmable frequency synthesizer; when the whole IF band has been scanned, the process will start again. Unidentified peaks in the power spectra are candidates for further study and their celestial coordinates will be recorded along with the time and power, IF and RF frequency, and bandwidth of the peak.

The 45m radiotelescope of Nobeyama Radio Observatory (NRO) is now in operation. It has a surface accuracy of 0.2 mm (rms) and a pointing accuracy of 0.001 degrees. Two types of spectrometers were designed for the telescope. One type is an Acousto-Optical-Spectrometer (AOS) with a 16,384 channel, 2000 MHz full-bandwidth spectrometer, and a 8192 channel, 160 MHz full-bandwidth spectrometer. The other type is a direct Fourier transform type spectrometer called “FX”. One FX is designed for a 10 meter, 5 element supersynthesis interferometer and another for the 45m radio telescope. The “interferometer FX” is a spectro-correlator that processes 5 inputs of 320 MHz bandwidth signals into correlations with 1024 frequency channels. The “45m FX” has 4 sets of 10 MHz bandwidth, 1024 channel spectrometers.

It has been pointed out by Morimoto, Hirabayashi, and Jugaku (1978) that formaldehyde anti-maser absorption lines in the direction of dark clouds would be suitable for SETI (Search for Extra-Terrestrial Intelligence). The Nobeyama 45m radiotelescope is suited for such targeted deep SETI.

It is shown that the energy requirements for interstellar colonization exceed that for intraplanetary colonization by a factor of ten million or perhaps much more. This is offered as an argument against extensive interstellar colonization as a means of dealing with population expansion, and as a possible explanation of the Fermi paradox.

Arguments are presented which show that motives for interstellar travel by advanced technological civilizations based on an extrapolation of Earth's history may be quite invalid. In addition, it is proposed that interstellar travel is so enormously expensive and perhaps so hazardous, that advanced civilizations do not engage in such practices because of the ease of information transfer via interstellar communication.

Is it our destiny to expand exponentially to populate the galaxy, or is such a vision but an extreme example of technological hubris? The overall record of human evolution and dispersion over the Earth can be cited to support the view that we are a uniquely expansionary and technological animal bound for the stars, yet an examination of the fate of individual migrations and exploratory initiatives raises doubts. Although it may be in keeping with our hubristic nature to predict ultimate galactic expansion, there is no way to specify how far expansionary urges may drive our spacefaring descendants.

Some of my more strident space-enthusiast friends wear T-shirts that say, “The meek shall inherit the Earth…the rest of us are going to the stars!” That may strike some as being overly optimistic at best, but I believe there is a grain of truth to it. Whenever I talk about space colonization or one-way voyages to the stars someone usually asks, “Who would want to go?” Usually someone else will the chime in, “I'll go!” Not only do people come in various sizes and shapes and colors, they look at the world in many different ways. I grew up in the suburbs of New York and knew people who had literally never been west of the Hudson River and had no intention of ever going. New York was comfortable. There is nothing wrong with that attitude. It is just that for many people such a life is not right for them. I went west as soon as I had the chance. I do not regret having left and am much more comfortable where I am now. As I have gotten older, I have found myself settling in and, although I like to travel, I am beginning to understand how those sedentary New Yorkers felt. The only difference is that I settled down a little later in life and in a different place from where I started. But some people never lose that need for adventure, that wanderlust, that need for a radical change, and new places. These are the people who will blaze the trail to the stars.

Even if long-lived advanced technical civilizations arise very frequently and interstellar colonization is possible and common among them, it is argued that this colonization process is unlikely to fully occupy the Galaxy (i.e., saturate it) due to interactions between the colonizing civilizations. This argument is supported by the analysis of population dynamics equations based upon those of theoretical ecology which are believed to be applicable to an extremely wide range of behavior patterns. It is also pointed out that recent astronomical evidence suggests that the disk of our Galaxy may be substantially younger than previously thought, thus making a non-saturated colonization model more plausible.

Why are we unaware of extraterrestrial intelligence?

Our understanding of the universe and the history of life on Earth suggests we may not be alone in the Galaxy. Today we are ignorant of where “they” are, if they are, as was Fermi when he asked, “Where are they?” Many scientists believe the way to seek for answers is to search for “their” radiated signature. (Hence SETI, now.) But some have argued persistently that since they are not here, they are not out there, and a few insist the situation is paradoxical. This note samples speculations supporting this view and concludes one cannot make a worthy paradox from absent evidence, a belief that interstellar travel will soon be a cinch, and a willingness to predict the distant future of intelligent species.

The choice of frequencies for SETI has been discussed by many authors. We wish to point out that the line spectrum provided by the hydrogen (H) atom is very rich, and covers a large spectral domain, from the ultraviolet to radio wavelengths. The frequencies of H lines present one remarkable feature, which in our opinion makes them more attractive than those of, e.g. the OH or H2O lines, or those chosen arbitrarily in the water hole: they all relate to only one atom, the simplest and most abundant one in the universe. In terrestrial alphabets, one word is composed of one or several characters. We can always replace any set of characters by a set of H frequencies, and “write” messages with them. Since the H frequencies are universally known, a “cosmic alphabet” could be constructed with them. In a mono-frequency search for artificial radio signals, the frequency of the H166 alpha line, 1425 MHz, might be a good substitute for the frequency 1420 MHz of the H 21cm line. In a multi-frequency search, the frequencies of the prominent Hn alpha lines near H 21cm might be interesting. There are about ten of them in the water hole. Finally, owing to the physical link between them and the H 21cm frequency, those around this symbolic frequency appear most attractive.

Since civilizations face always problems that require continuously greater activity, it is likely that supercivilizations will undertake activities and construct structures of a very large scale. Properties and means of detections of such superstructures and activities are discussed. We also examine six possible scenarios on the evolution of civilizations.

One of several explanations for the Fermi Paradox is that the whole Galaxy, including our Solar System, has already been colonized, but that for a variety of reasons the extraterrestrials have chosen not to reveal their presence. In a universal search for extraterrestrial intelligence, it seems prudent to check-out also our own backyard. IRAS has obtained a large volume of infrared data at 12, 25, 60 and 100 microns from which a special working group at JPL, of which the author is a member, is trying to establish a special catalogue of Solar System objects, the vast majority of which are asteroids. A careful search through this data bank for objects with peculiar infrared spectra would be the first step in the search for major artificial objects, such as space stations or materials processing plants, in our Solar System. The asteroid belt is an ideal source of raw materials for space colonies, which could have easily escaped detection lost among the many thousands of natural asteroids. Checking them out for excesses in the infrared is an ideal screening test for artificial objects in our Solar System.

As this successful Symposium is drawing to a close, let me bring to your attention some important questionmarks that still remain unanswered and for which we will hopefully have some better answers in our next meeting in Hungary in the summer of 1987.

Wandering in the wilderness (1) of search space and (2) among the stars.

The quest for extraterrestrial life and for other stellar civilizations has finally become an international scientific endeavor. As our technology advances and major astronomical observatories are established in space, we will be able to gain a better understanding of ourselves and the Cosmos.