Exploring the Search for Extraterrestrial Intelligence

The scientific search for extraterrestrial intelligence rests on the assumption that the alien races we are searching for will turn out to be similar to us.  It is widely believed that they will be carbon-based life forms on the surface of planets like our Earth, orbiting around a star like our sun.  There may be other types of intelligent life existing on other types of planets or even in open space.  Isaac Asimov once considered every planet in our solar system and pointed out a substance that could be liquid, a substance that could form complex chemical compounds and a source of energy that could drive chemical reactions.  All these appear to be necessary for what we define as life.  The different possible modes of existence form a spectrum of possibilities from very similar to ourselves, to so different as to be unrecognizable.  The more different a life from is from our own, the more difficult communication may be.

If an alien species is a carbon based biological life form on a planetary surface not too different from ours, there are still questions about structure.  There are arguments for and against the probability of a humanoid body shape.  While there are similarities in the basic structural elements of nervous systems in terrestrial creatures, there are also important differences.  The brains of extraterrestrials will also probably include important similarities and differences when compared with our own.  The farther they are from us in biology and brain structure, the harder it may be for us to decipher any communication.

They could possibly have radiation sensors like our eyes for some band of electromagnetic radiation.  They could take in a portion of the spectrum wider or narrower than ours and they could use more, less or different visual parameters than we do.  For example, we have three dimensions of color perception but some birds have four dimensions and dogs have no color perception.  The resolution of alien eyes could be greater or less than ours, and they could organize their perception of visual form differently than we do.  These factors are important to any discussion of communication because aliens might transmit some sort of visual images.

Sensors for atmospheric pressure changes are also likely.  On Earth, there is tremendous diversity of hearing with respect to the sensitivity, bandwidth and location of frequency band.  Bats hear far into the ultrasonic range and whales hear into the subsonic.  If audio signals are sent, any differences in hearing might be important.

Many creatures, from bacteria to pigeons, have the capacity to detect electric and/or magnetic fields.  There is speculation that human beings can also sense these fields.  We do not appear to have conscious access to such perceptions and there are no words to deal with the "meaning" of such information.  If aliens used such esoteric senses, their forms of communication could be radically different from ours.

The relationship of environmental sensing to communication is important.  We use a passive visual mode, which senses reflected light to comprehend our environment and an active transmission system of air pressure changes to communicate directly with each other.  The area of our brains which analyzes our visual input is at least ten times as powerful as the area we use to analyze sound.  We can speak of things that cannot be seen and see things we cannot speak of.  Many human communication problems are caused by the dichotomy between our basic environmental sensing mode and our basic communication mode.  This difference has left an indelible stamp on our philosophy and civilization. 

In contrast, dolphins use an active pressure scanning and reflection system in the ultrasonic range to sense their environment and an active pressure transmission system for communication.  They use the same areas of their brain for both tasks and they do not have the confusion between the seen and the spoken that we have.  Any extraterrestrial civilization created by creatures using a similar combination would be very different from our own.  The type of sensory apparatus that a species utilizes to sense their world and to communicate with each other will have a big impact on the manner in which they would attempt to communicate with another species. 

The intelligence of the average member of an extraterrestrial species might be much lower, about the same as, or much higher than, the intelligence of the average human being.  We assume that extraterrestrial races would organize their conceptual universe in a fashion that would be basically comprehensible to us.  Considering the problems various groups on Earth have in comprehending each other, this may be a vain hope.  If their intelligence is very different from ours we may not be able detect and/or decode any message from them.

If we are fortunate enough to receive a message from a race that is not too different from us in biology, intelligence and/or mental organization, we still have to be concerned with the values and motivations of the extraterrestrials.  Regardless of intelligence, cultural values will influence the motivation to communicate.  Human beings communicate for survival, self-aggrandizement, religious and political recruitment, loneliness, charity, etc.  Motivation will inevitably play a role in the form and the content of any message.  If we do decipher a message from space, we may not understand the motivation behind it. 

In order to build and power devices for interstellar communication via some physical media, an alien race will have to be far beyond our current capabilities.  The capacity to harness enormous amounts of power will be essential.  The ability to travel in space will probably be necessary.  They will have to be able to design and build huge artificial constructs.  They will need the will, as well as the ability, to allocate the necessary resources.

Surface conditions of their planet as well as their biology and mental organization will shape the technological "style" of any alien race.  We assume that any transmission will take place in the electromagnetic spectrum at the frequency of basic hydrogen or the hydroxyl radical in the billion-cycle range.  This may or may not be the case for reasons ranging from practical utilization of energy sources to efficiency of transmission systems to aesthetics. 

Even at our level of scientific evolution, we can envision a variety of alternative transmission media.  Extraterrestrials may use exotic particles such as neutrinos or tachyons to transmit their messages.  They may use gravity waves to send distortions in the fabric of space-time.  If they have reached a level of understanding about the nature of reality beyond our own matter-energy-space-time explanations, they may communicate by media that we don't, and maybe can't ever, comprehend.  If those involved in parapsychology research are correct about untapped powers of the human mind which can transcend space/time, certain sensitive individuals may have already had messages from alien civilizations transmitted directly into their brains.

Because we accept the assumption that nothing can travel faster than the speed of light, we believe it unlikely that an alien civilization would attempt to send a message in any form other than a transmitted sign.  Even with the speed of light as a limiting factor for travel, there are possibilities for generation ships, suspended animation craft, robot probes or "greeting cards" similar to the plaque that we recently sent out of the solar system.  If the speed of light can be transcended by physical objects, an alien race might not waste the energy and time to send out electromagnetic messages which would take centuries to arrive and be returned.  The UFO enthusiasts believe that extraterrestrials are from planets in our universe and are physical beings who have mastered technologies which give them capabilities far beyond ours, including the ability to exceed the speed of light.  They assume that communication will be by direct physical visits and have already occurred on a frequent basis.

We expect the form of any message to be some sort of complex modulated wave.  If this is the case, how will we recognize that a particular received signal is an artificial construct? The senders may work to make it easy to recognize by sending a string of pulses representing a series of prime numbers or another easily recognizable artificial pattern.  On the other hand, senders might make a message deliberately hard to recognize to filter out less intelligent listeners.  Another potential problem will be the time scale.  We are scanning many frequencies and possible sources but not spending much time on each one.  Any recognizable signal will have to be short enough that we see it, but repeated often enough that it will be on a particular frequency band when we happen to be scanning it. 

Once we have what we think is an artificial signal, how do we begin to decipher it? The suggestion of simple mathematics as the basis for a code is predicated on the assumption that such basic patterns will be discovered everywhere.  Prime numbers are prime numbers throughout the universe.  If we saw a signal with one pulse, followed by two pulses, then three, five, seven, etc., we would be confident it was artificial.  Another possible message form could be a series of pulses equal to a square number such as 10,000 with two or more possible amplitudes for each pulse.  We could try assembling a square picture with a white, black or gray pixel at each location depending on the string of pulses.  Star charts, tables of elements, solar system diagrams, surface maps, pictures of aliens or any other "visual" image could be transmitted.  This brings us back to the sensory problems involving modalities for sensing the three dimensional environment, levels of resolution, neurological organization, etc.

If we did receive an interesting radio transmission, were able to recognize it as artificial, and were able to decode it into something we could comprehend, what then? What might the content of the message be?  Most of the SETI researchers assume that it will be technical information about the physical universe.  However, this would require that the senders understood our conceptual framework, level of development, sense of significance and other aspects of our society.  This would be impossible for any potential sender to know.  To successfully send this type of information, the motive of the sender would have to be educational, the message would have to be decipherable by a wide variety of intelligences and the information would have to amount to an interstellar encyclopedia with different levels of explanation from elementary to advanced.  In reality, the content of any message might be scientific, religious, political, artistic, and humorous or something we can't possibly understand.  The assumption that the subject of a message would be "scientific science" may be more of a hope.  The farther from physical science the content is, the more difficult it will be to comprehend the message

We may understand part of the message, but not all of it.  We may think we understand what the message means, but we may be wrong.  There may be different interpretations of the same message.  Look at the debates that have raged between political or religious factions over the interpretation of the texts of the founders of their movements.  We may receive more than one message over time from the same source.  A later message may say, "Disregard prior message".  We have to seriously consider that any of the information contained in a message might not be accurate or true.

The revelation of a message from an extraterrestrial civilization would send shock waves through human society.  Intense effort would be applied to deciphering the message.  If we could decode it, great debate would follow on the meaning of the message.  Some groups would react fearfully and governments might fall.  Some groups would be certain that the millennium is at hand, regardless of the translation, and cults might form.  Other groups might gain knowledge and power from the message contents and exploit that knowledge to their own advantage.  The unequivocal reception of a message from another race around another star would be the most significant single event in the history of human civilization and the knowledge that we are not alone would change human perspectives forever.