Lo, what fools these mortals be.

About a tenth of Americans claim to have observed a UFO or been witness to some event that they attribute to the activity of extra-terrestrials. The number claiming actually to have met or been physically abducted by aliens from outer space is happily much lower, but the belief that this experience is real is astonishingly widespread. For not a shred of credible evidence exists to support such tales. The encounter with sentient beings from another world is a common theme of human literature and fantasy, ranging from Shakespeare through to modern-day computer games, and taking in the myths and morality tales of most of the world’s religions. A Midsummer Night’s Dream, for example, depicts a parallel world in which immortal beings, endowed with far-reaching powers including hypersonic flight and an advanced understanding of behavioural pharmacology, intermingle with humans, whilst remaining invisible to them except when they choose to reveal themselves in caprice. Shakespeare’s fairies, though technologically far advanced, are still prone to human foibles such as lust and jealousy, and simply can’t resist interfering in the affairs of mankind, both to settle their own scores and arrogantly to correct humans’ own failings. Indeed, the play contains one of the most celebrated depictions of alien abduction. The Book of Genesis presents a more didactic view of extra-terrestrial intervention in the affairs of humanity. Adam and Eve, fashioned out of the same stuff as the divine, are relegated to earthly toil in order to prevent their acquisition of the knowledge required to regain immortality, until such time as they prove themselves morally worthy thereof. The warning remains relevant today, standing as we do, most likely just a few centuries short of functional immortality. Our development of technologies for good remains finely balanced against our application of advanced knowledge to destroy both ourselves and all the life of the planet on which we live Although there is no scientifically reliable data to indicate the existence of living beings beyond our own planet, the assumption that life in some form is widespread in the universe is shared not only by poets and prophets, but also by most scientists, including both cosmologists and biologists. The discovery of exoplanets in the past decade, of an increasing variety of properties and composition, has led to an expectation that at least an indirect signature of life elsewhere in the universe might also be detected during the lifetime of most of us. Whether this will prove to be ‘life as we know it’, based on DNA, membranes and ribosomes, spread throughout the cosmos in the icy cores of comets and meteorites, or else founded on more exotic chemistries, is obviously a matter for speculation. If, indeed, life is a commonplace in the vast reaches of space, it is surely improbable that our own relatively young planetary system has produced the most advanced civilization in the universe. The possibility that there are millions of other such entities out there, including some billions of years older than our own, leads to a classic conundrum much loved of science fiction writers. Why, in this case, has none of those civilizations actually chosen to make contact with us, passing on some useful knowledge, or schooling us in wiser ways? One discomforting answer is that the Garden of Eden story might contain more than a grain of truth. Perhaps we have been deliberately shunned, a pariah planet, tainted by moral corruption, unworthy of being seated at the intergalactic high table. Our moral evolution lags too far behind our scientific ability. We cannot yet be trusted with the knowledge ‘they’ hold: the risk is too great that we would use it for vain or destructive purposes. It is blindingly obvious that any advanced extra-terrestrial civilization must have perfected cloaking technology, enabling them to remain undetectable. Thus, they may be patiently sitting out the millennia in silence, waiting for us to be worthy of being contacted. Or maybe a few renegades have been unable to resist the temptation to interfere occasionally in the affairs of humans, whether in trollish caprice or as agents of moral revelation. All this is already well entrenched in ancient myth and modern science fiction. How would the knowledge that such civilizations actually exist alter the way we live our lives or the way we practice science? If we were certain that a much more profound explanation of the universe could be accessed simply by plugging into a cosmic Wikipedia, would we still bother to do experiments? I’d urge instead that we should strive even harder to get it right. Extraterrestrial reviewers might turn out to be less forgiving than their human counterparts. But if they don’t exist, the responsibility on our shoulders is all the greater: it’s all down to us. There is surely a wider message for humanity too. The knowledge that immortality and true wisdom might be attainable, if accompanied by moral perfection, should bring about a profund change in human behaviour. But if this condition must be fulfilled before extra-terrestrials around us reveal their existence, we may be in for a very long wait. Past generations lived their daily lives in constant fear of heavenly judgement. But, irrespective of alien intervention, if we voluntarily live up to the moral ideals we espouse, we will create a better world anyway.