Should we attempt to start a dialogue with intelligent aliens – assuming they exist?

 

The pros and cons of attempting to notify the Galaxy of our presence have been debated since the dispatch of the Arecibo Message in 1974. In the wake of this transmission, US diplomat Michael Michaud suggested that the Message had repercussions that went beyond science into the realm of politics. He proposed a public discussion of the possible benefits and risks of establishing contact. More strident was the protest by Martin Ryle, the British Astronomer Royal, who argued that "any creatures out there [may be] malevolent or hungry." He requested that the International Astronomical Union approve a resolution condemning such attempts at CETI. However, in a letter to Ryle, SETI pioneer Frank Drake pointed out that:

 

It's too late to worry about giving ourselves away. The deed is done. And repeated daily with every television transmission, every military radar signal, every spacecraft command ... I think that hostile tribes bent on war, be they terrestrial or extraterrestrial, destroy themselves with their own weapons, before they have any notion of how to attempt interstellar travel.

 

The argument thus quickly and inevitably became entwined with a debate about the likely nature of intelligent extraterrestrials (see extraterrestrial intelligence, character), those in support of CETI favoring the view that high intelligence will generally be benign, while those in opposition warning of dire consequences, including potential invasions and even cannibalism, if our whereabouts became widely known. In the latter camp is Michael Archer, professor of biology at the University of New South Wales, Australia, who believes the phonograph records attached to each Voyager probe could effectively serve as giant dinner invitations proclaiming "Come to Earth, we have lots of nice, exotic things to eat." At the other extreme, Carl Sagan and William Newman proposed that there may exist a "Codex Galactica" to educate young societies, like our own, in appropriate forms of behavior. As for the dangers of humankind literally falling prey to an alien race, Sagan pointed out that advanced extraterrestrial carnivores would almost certainly find our particular combination of amino acids unpalatable. Moreover, it would hardly be cost-effective in energy terms to cross interstellar distances merely to find something to eat, when a fraction of that energy could be used to synthesize food locally on a large scale.