THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE

Posted by admin_akashic on Jun 27th, 2022 in Space

Nevertheless, SETI might survive on a weaker interpretation of its programme. The weaker version accepts the contingency of science and radio communication. It does not have to show any commitment to beliefs about the evolution of science, and would accordingly admit much lower probability rates for any of the factors in the Drake equation. The search could continue, but with less optimism. The aliens may not be like us but if there are enough of them, perhaps just a few will be like us and develop along broadly similar lines, having encountered broadly similar problems relating to survival, notwithstanding a variety of different means of reaching a similar goal to ours. Thus a radio search may still be justified, even though it assumes a similar natural history, technology and culture to ours, which, according to Munévar, is highly unlikely. This would be a search with only a slight possibility of success, but it would have the advantage of focusing on a possible intelligence that is meaningful at our level of understanding.

SETI scientists could, however, admit that there are many contingencies in the development from prebiotic life to radio astronomy but insist that on the way there are certain threshold states which make the next stages more probable. Some stages in evolution are so important to survival that it does not matter how they are reached. The phenomenon of equifinality has been frequently observed in biology, whereby organisms reach a certain advantageous state by many different means. Once past the threshold state then other stages have a greater degree of inevitability about them. For example, once a species develops speech it has the faculty to express humour, tell stories, produce poetry and educate. Once a society has a computer the threshold towards high technology is almost inevitable.

In reply to their critics, SETI scientists could argue that the Drake equation and its analogies with the emergence of terrestrial intelligence are heuristic not probative. They could point out that, since the scientific revolution, it has been recognized that attempts to deduce the nature of physical reality from first causes are doomed, and that the case for or against SETI can only be determined experimentally.

Eventually, if not already, SETI’s appeal to an experimental basis must face another line of criticism – one that is familiar to the theologians.

The Great Silence: Fermi’s Paradox

Enrico Fermi, the Italian physicist, responded to the arguments in favour of ETI with his now famous retort – where are they? This has become known as Fermi’s Paradox, whereby all the arguments indicate the existence of ETI but there is no evidence of their existence. Where are they, if they have had millions of years to settle here? The Earth is about 4,600 million years old, with human life emerging 2 million years ago, electricity and radio less than 200 years old, and space flight less than fifty years old. But the universe was at least 10 billion years old when the Earth was formed, which has allowed plenty of opportunity for

157

many other civilizations to have emerged. Some of them could have been in existence for millions of years before the origins of human life. This is long enough for them to have explored the entire galaxy. They ought to have been here by now. So where are they?, asked Fermi.

Evidence of the Great Silence is the strongest case against SETI. Parallels with the theological problem of silentium dei are striking. Bertrand Russell was once asked what he would say if God called him to account for his atheism. Russell allegedly replied that he would respond to God by asking Him why He made evidence for His existence so poor. This seems to be the case with ETs.

Scientists with the US military have deployed a world-wide space surveillance system consisting of telescopes and sophisticated radar equipment which can track spacecraft. Every object over 10 centimetres in diameter has been catalogued, of which there are over 7,000. In addition, there are over 10 million fragments of debris, none of which can be attributed to an extraterrestrial source. So far no extraterrestrial artefacts have been discovered and no information regarding the communicative intentions of extraterrestrials has stood up to scrutiny. However, it might be argued that [1] we would not be capable of recognizing their products; and [2] we might not have found them. It only takes a few generations for a whole civilization to disappear as we know of the vanished civilizations of Asia and Africa, and cities completely obliterated by the elements within a millennium or two.

Hart’s case for the uniqueness of humans

The fact that the inhabitants of planet Earth have entered the space age and contemplate colonizing voyages throughout the solar system and beyond has lent support to SETI’s opponents. If we are but a few centuries away from interstellar voyages, might it not be the case that our ET neighbours are in the same position? If we are on the threshold of colonizing the galaxy – a mere million or two years away – then why haven’t others, with an earlier start, done so already? This paradox was examined by M.H. Hart (1975) who argued that the obstacles to interstellar travel have been over-exaggerated and that the only reason the galaxy is not teeming with intelligent life is because we are unique. The force of Hart’s argument cannot be underestimated: SETI’s credibility rests on the argument that technological intelligence is widespread. If this is the case, maintains Hart, they must be here.

Hart’s attempt to demolish explanations of the Great Silence is worth elabo-ration. First, he rejects physical explanations which claim that extraterrestrials have never arrived because ‘some physical, astronomical, biological or engineering difficulty makes space travel infeasible’ (Hart, 1975: 128). Space travel, he argues, does not present insurmountable problems. It may be the case that a one-way trip to Sirius at the speed of light would take eighty-eight years which is well beyond current technology. But Hart sees ways of overcoming such problems: youthful voyagers in states of suspended animation; using drugs to

158