THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE

pulses as narrow as 1021 sec’ (ibid.: 321). These neutrino timing pulses can be produced with briefer timing and greater luminosity than pulses of electromag-netic radiation. Learned et al. point out that the ‘production and decays of W and Zo bosons are the fastest processes known in physics’ (ibid.: 324) and they suggest that it is likely that an advanced intergalactic civilization will employ timing pulses using electron neutrinos from the decay of Zo bosons. Not only are they of shorter duration and greater luminosity than electromagnetic pulses, they can penetrate and still remain bright; they would not be blocked by interstellar dust or be dispersed in space. Neutrino signals would also be extremely distinctive and are unlikely to be mistaken for naturally occurring processes. Zo bosons could be created by colliding high energy electrons and positrons head-on. Thus giant particle accelerators would be employed as transmitters. But in order to transmit signals across the galaxy these transmitters would have to be the size of the Earth.

Obvious objections can be made regarding our lack of any idea as to how these accelerators could be assembled. But let us assume, for the moment, that advanced extraterrestrials have overcome all technical obstacles. How could we listen in to these neutrino messages? The decay of the Zo boson produces equal numbers of all three types of neutrino, one of which – the electron anti-neutrino could be detected by a receiving beam of high energy electrons. If this beam contacted the incoming electron anti-neutrinos, then W-bosons would be created. If an advanced civilization is transmitting, they could be detected on Earth by the next generation of neutrino telescopes, some of which are located beneath the oceans. For example, Learned et al. suggest that the Deep Under-water Muon and Neutrino Detector (DUMAND) which is being constructed beneath the ocean, could receive a signal from a neutrino transmitter within a distance of 3,000 light years. So if they are busy colonizing, then their timing methods may be detected on Earth.

The technical problems, however, are enormous. There is no plausible description available concerning the construction of the accelerator-transmitter. But if such an object was constructed we might very well be able to observe the transmitter, not merely its messages, from the infrared energy. In fact a civilization capable of producing an intergalactic neutron transmitter would, like Kardaschev–DysonType III civilizations (see Chapter 7), require enormous amounts of energy that could be detected in a search for infrared sources.

 

Decoding the message

Cocconi and Morrison (1959) suggested that the opening of the message would involve some attention-seeking device, something obviously artificial, like a sequence of pulses representing  prime numbers. Then the message might contain familiar information, such as well-known scientific laws. Whatever form it takes, decoding an ET message could be a major undertaking. Until the discovery of the Rosetta Stone, European scholars devoted over a century of

 

 

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wasted energy trying to decode ancient Egyptian hieroglyphics. Some ancient languages, such as the Glyphs of Easter Island and the writings of the Mayas, are still uncoded. Yet these languages reflect a similar biological form and territorial niche in the universe to us. How much harder will it be to translate messages from a distant galaxy from beings of whom we know nothing?

There have been a number of attempts to devise basic systems of communication that can be shared by different beings across the galaxy, but all so far are badly flawed. We only need to consider the difficulties humans encounter when trying to communicate with dogs – a species that has evolved alongside humans on Earth since the hunter–gatherer stage of human existence. Volumes of books have been written on how to communicate with pets who share our homes, yet much of their lifestyle and ways of signalling to each other are beyond our comprehension. If it is so difficult with members of our extended ‘families’, consider how much more difficult it will be with extraterrestrials. Frank Drake (Drake and Sobel, 1993) recalls a simple black and white message, which he devised, of zeros and ones, consisting of 551 characters, being the product of two prime numbers, 29 and 19. The characters formed a picture which gave information about our solar system, diagrams of oxygen and carbon molecules, the shape of human beings, and representations of humans in binary code. He sent this ‘simple’ message to other scientists engaged in SETI research and to several Nobel prizewinners. None of them interpreted the message as intended by Drake, although a year later an electrical engineer who was an amateur code-breaker, successfully deciphered it. He was the only one to do so!

In 1960 the mathematician, Hans Freudenthal, devised a language for intergalactic communication which he called Lincos. Lincos is an artificial language, not designed to be spoken, which, in contrast to all natural languages, avoids irregularities and exceptions. Based on pure logic and mathematics, without any cultural accretions, it is built up in the form of a dialogue based on signs; pointing to objects, repeating the use of symbols in various contexts to reduce uncertainty. For example, in the dialogue between A and B, A asks: ‘what is 2 + 3?’, and B answers: ‘2 + 3 = 5’, and A says ‘correct’. Then A asks ‘what is 10 × 10?’. B says ‘20’, so A says ‘incorrect’ and so on. This exchange is designed to convey the meaning of words like ‘correct’ and ‘incorrect’. The mode of communication was intended to be via radio bleeps, which would indicate mathematical symbols, rather than by ostensive behaviour. Given that we have little idea of their physical structure, environment and culture, more sophisti-cated forms of communication could be withheld.

In a review of Lincos, S.W.P. Stern (1962) suggested that communication should be limited to mathematics until we are sure what kind of beings we are dealing with. But how do we know that other intelligent beings will appreciate mathematics? If they have memories and can perceive the present falling into the past, says Stern, they will have the minimum requirement for developing mathematics. But even their mathematics could be different, and it is not obvious that any form of applied mathematics would have any similarity. It is unlikely

 

 

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