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Meet the neighbours: Is the search for aliens such a good idea?

We've been trying to make contact with aliens for years. Now the day is fast approaching when we might finally succeed. But will our extraterrestrial friends come in peace? Or will they want to eat us? Astronomer David Whitehouse explores the perils of a close encounter

We are making dangerous discoveries in space. In April, astronomers found, on our cosmic doorstep, a planet dubbed Gliese 581c. Nestling close to a dim red star, it's a rocky world only a little larger than Earth. Like Earth, it could support liquid water. And to scientists, liquid water means the possibility of life.



Gliese 581c must be an ancient world, for it circles a star that is far older than our Sun. The question is, has any advanced life evolved on that planet, or on the many other places that must be suitable sites, not so very far away?



Recently, British astronomers told the government that we might find life in space. It is only a matter of time, this year perhaps, before astronomers detect a planet even more similar in size and mass to our Earth, circling another star. And when we find that planet, we may discover a lot more than new oceans and land masses.



Astronomers have been actively looking for intelligent life in space since 1960, when Frank Drake started Project Ozma, using a radio telescope to listen for signals from two nearby sun-like stars - Drake knew that radio waves travel more easily through the cosmos than light waves. He didn't hear anything back. Since then, our searches have become more thorough thanks to larger radio telescopes and more sophisticated computers that look for fainter signals. But we still have no signal from ET. Should we want to?



This is not just a matter for astronomical research involving distant worlds and academic questions. Could it be that, from across the gulf of space, as HG Wells put it, there may emerge an alien threat? That only happens in lurid science fiction films, doesn't it? Well, the threat is real enough to worry many scientists, who make a simple but increasingly urgent point: if we don't know what's out there, why on Earth are we deliberately beaming messages into space, to try and contact these civilisations about whom we know precisely nothing?



The searchers are undeterred. They argue that because of the vastness of space - even if there are 10,000 transmitting societies nestled in the stellar arms of the Milky Way - we might have to search millions of star systems to find just one.



But rather than just listening, some want to announce our presence to the cosmos. In 1974, the then newly resurfaced Arecibo radio telescope in Puerto Rico (made famous in the James Bond film Goldeneye) reversed its usual role of just listening, and transmitted a series of radio pulses towards the M13 star cluster. It sent 1679 pulses in all, which, when arranged in binary form into 23 columns and 73 rows, would form a message from humanity. It was seen as a symbolic gesture, showing those on Earth that we had the technology to send a signal across our galaxy and - if we were on the other side of the relationship - to receive a signal as well. But some scientists objected. Sir Martin Ryle, the Astronomer Royal at the time, warned that " any creatures out there [might be] malevolent or hungry".



Now, after a long period when there were no deliberate transmissions into space, a new round is about to take place and more are planned. A team led by the astronomer Alexander Zaitsev has already beamed forth a series of interstellar messages, including pictorial and musical transmissions, from the Evpatoria radio telescope in the Ukraine. Another group in Brazil, the Grupo Independente de Radio Astronomos in Rio de Janeiro, claims to have transmitted as well. Half a dozen commercial companies have also sprung up, among them Cosmic Connexion, a firm based near Cape Canaveral in Florida. The Cosmic Connexion website invites you to e-mail your messages to them and they will then beam them, free, into space and "introduce you to extraterrestrials". At the moment, though, this is a low-power initiative whose signals won't get far. Other companies offering the same service for a fee are soon to come online.



Many scientists, frightened by the danger that might lurk out there, have argued against our actively seeking contact with extraterrestrials. Jared Diamond, professor of evolutionary biology and Pulitzer Prize winner, says: " Those astronomers now preparing again to beam radio signals out to hoped-for extraterrestrials are naive, even dangerous."



The fact is, and this should have been obvious to all, that we do not know what any extraterrestrials might be like - and hoping that they might be friendly, evolved enough to be wise and beyond violence, is an assumption upon which we could be betting our entire existence. When I was a young scientist 20 years ago at Jodrell Bank, the observatory in Cheshire, I asked Sir Bernard Lovell, founder of Jodrell Bank and pioneering radio astronomer, about it. He had thought about it often, he said, and replied: "It's an assumption that they will be friendly - a dangerous assumption."



And Lovell's opinion is still echoed today by the leading scientists in the field. Physicist Freeman Dyson, of the Institute for Advanced Study in Princeton, has been for decades one of the deepest thinkers on such issues. He insists that we should not assume anything about aliens. "It is unscientific to impute to remote intelligences wisdom and serenity, just as it is to impute to them irrational and murderous impulses," he says. " We must be prepared for either possibility."

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The Nobel Prize-winning American biologist George Wald takes the same view: he could think of no nightmare so terrifying as establishing communication with a superior technology in outer space. The late Carl Sagan, the American astronomer who died a decade ago, also worried about so-called "First Contact". He recommended that we, the newest children in a strange and uncertain cosmos, should listen quietly for a long time, patiently learning about the universe and comparing notes. He said there is no chance that two galactic civilisations will interact at the same level. In any confrontation, one will always dominate the other.



The Australian astronomer Ronald Bracewell, now of Stanford University, warns that other species would place an emphasis on cunning and weaponry, as we do, and that an alien ship dispatched our way is likely to be armed. Indeed, evolution on earth is, as they say, red in tooth and claw. And it's likely that any creature we contact will also have had to claw its way up its own evolutionary ladder and may possibly be every bit as nasty as we are - or worse. Imagine an extremely adaptable, extremely aggressive super-predator with superior technology.



So should we stay quiet and ban these transmissions into space? When, as a newly minted young scientist, I was discussing this issue with the (late) influential astronomer Zdenek Kopal, he grabbed me by the arm and said in a tone of seriousness: "Should we ever hear the space-phone ringing, for God's sake let us not answer. We must avoid attracting attention to ourselves." Others have put it more graphically, saying that the civilisation that blurts out its existence might be like some early hominid descending from the trees and calling "here kitty" to a sabre-toothed tiger.



But not all scientists are worried. Frank Drake, who devised Project Ozma and who was also behind the Arecibo transmission says, "As I thought in 1974, the objections to sending interstellar messages were naive and carried no weight. The argument then, as now, is that humanity has been, and is making, its presence known through our TV and radio and military radars which, in many cases, release most of their radiated power into interstellar space."



Radio waves from Earth, from TV and radio broadcasts and from powerful intercontinental military radars are leaking out into space. Some believe they could be detected, but should we go beyond this and actively announce our presence to the cosmos? Drake points out that our present terrestrial radio telescopes, if placed on nearby worlds, would be unable to detect these transmissions at distances beyond a few light years. However, aliens would be more advanced, he says, and it is quite within the abilities of current terrestrial technology to build telescopes, using the array approach, which could detect these transmissions from great distances in the galaxy.



"The point here is that Earth has made its presence known by sending a multitude of signals. It is too late - we have made ourselves visible," he adds.



But scientist and science-fiction author David Brin thinks those in charge of drafting policy about transmissions from Earth - ostensibly a body called the International Astronomical Union, which would make recommendations to the United Nations - are being complacent, if not irresponsible. Whatever has happened in the past, he doesn't want any new deliberate transmissions adding to the risk. "In a fait accompli of staggering potential consequence," he says, "we will soon see a dramatic change of state. One in which Earth civilisation may suddenly become many orders of magnitude brighter across the Milky Way - without any of our vaunted deliberative processes having ever been called into play."



Michael Michaud, a former US diplomat and chairman of the Transmissions from Earth Working Group - a subdivision of the International Astronomical Union's Search for Extraterrestrial Intelligence Study Group established in 2001 - is on the verge of resigning in frustration at the lack of discussion about the problem. He believes it is being confined to a narrow group of scientists who share the same limited astronomical viewpoints and he wants the study group widened beyond its current remit to include planetary scientists, philosophers, historians and so on. He sees it as a problem that affects all of humanity - and one that should be debated as such.



But despite these concerns, for the moment, the plans for deliberate transmissions from Earth go ahead and there is nothing anyone can do to stop them - or even demand a discussion beforehand.



One thing is clear from our searches for ET - there is nobody transmitting strong interstellar beacons in our local vicinity. If "they" are out there, they are keeping quiet, prompting the question that they might know something we don't.



Perhaps the aliens already know about us and are on their way. Or perhaps not. Intelligences - possibly vast, cool and unsympathetic - could be sweeping their skies looking for us. At the moment when they point their instruments in the direction of our sun - a commonplace yellow-dwarf star - they may well find nothing unusual, if no one's sending messages in the other direction. Should we keep it that way?



Searching for ET: the truth is out there

The Seti (Search for Extra-Terrestrial Intelligence) Institute in California is the only such group that searches the cosmos for signs of intelligent alien life. It does so by listening out for radio signals.



Seti, which was founded in 1984, has 100 scientists, educators and support staff. Its funding from the American government was cut off in 1992 and it now relies on private donations.



The institute's Project Phoenix was the most ambitious search for extraterrestrial intelligence ever undertaken. From February 1995 to March 2004, Phoenix conducted three observing campaigns on some of the world's largest radio telescopes, targeting stars within 240 light years of Earth.



In more than 11,000 hours of observing, using telescopes in Australia, West Virginia and Puerto Rico, Project Phoenix "tuned in" to more than 800 stars. No ET signals were detected.



The next stage in the search is the Allen Telescope Array, currently under construction in California. Partly funded by the Microsoft billionaire Paul Allen, it will eventually consist of 350 20ft dishes making synchronised sweeps of the sky looking for alien signals (see www.seti.org).



Postcards to the edge



ARECIBO (1974)



This message was sent from the Arecibo radio telescope in Puerto Rico to the M13 star cluster, 25,000 light years away (150,000 million million miles). Consisting of 1,679 binary digits, the bits can be arranged into a rectangle of 73 rows and 23 columns (two prime numbers) to reveal a message.



Encoded are: the numbers one through to 10; atomic numbers of key elements such as hydrogen, carbon and oxygen; a graphic of DNA, along with an estimate of its complexity; a graphic figure of a man and the human population of Earth; a graphic of our solar system; and a graphic of the Arecibo radio telescope.



The signal took 169 seconds to send and was not repeated.



COSMIC CALL (1999, 2003)



The first public interstellar messages were sent from the Evpatoria Deep Space Center in Ukraine. Signals were sent twice in 1999 and once in 2003 towards five nearby Sun-like stars about 50 light years away. The 1999 message consisted of 23 black and white stylised images starting with the basics of mathematics and ending with humans. The 2003 message consisted of 12 images.



TEEN-AGE MESSAGE (2001)



Composed by Russian teenagers, this was transmitted from Evpatoria to the Sun-like star HD 197976 in the constellation of Delphinus. The two-hour transmission, in three parts, included 15 minutes of music played on a theremin.



First contact: a literary guide



THE WAR OF THE WORLDS BY HG WELLS (1897)



The first-ever novel to imagine an invader from outer space, Wells's 1897 fantasy sees the Martians abandoning their dying planet and landing in ten spaceships on southern England. When Earthling overtures of friendship are met by lethal Heat Rays, crowds flee in terror through the streets. Wells used the mild suburbs (like Woking) to brilliant effect, turning their offensive streets to a rubble-strewn wasteland. Just when the invasion seems unstoppable, the aliens are destroyed not by military strategy but something much simpler: terrestrial Earth germs.



2001: A SPACE ODYSSEY BY ARTHUR C CLARKE (1968)



Expanded from a 1948 Clarke short story called "The Sentinel", about intelligent life in the universe being given a helping hand by an ancient alien race, this ambitious narrative starts in 3,000,000BC, with the appearance on Earth of the alien monolith, which inspires a group of apes to use tools. The monolith is discovered on the Moon in 1999 and emits a piercing signal into deep space. The ship Discovery sets out to find the signal's source on Saturn, piloted by an intelligent computer HAL 9000. When it malfunctions and kills most of the crew, one man reaches the alien " star gate" and is recreated as an immortal, all-powerful Star Child.



STRANGER IN A STRANGE LAND BY ROBERT HEINLEIN (1961)



The Stranger is Valentine Michael Smith. He isn't an invader, but a returning Earthling, who was born on Mars and brought up by Martians. His perspective is alien, his intelligence superhuman, as he is guided into earth concepts of war, clothing, jealousy and God. Smith founds a Martian-influenced Church of All Worlds, preaching transcendence above pain, sickness, hunger and war. The church is destroyed, and a mob kills him, but he survives as a voice preaching the primacy of the soul. Is he Christ, or Prometheus, or the Archangel Michael? Take your pick.



THE MAN WHO FELL TO EARTH BY WALTER TEVIS (1963)



Familiar to all from the Nicolas Roeg movie starring David Bowie, Tevis's eponymous man is Thomas Jerome Newton, a humanoid from the planet Anthea, where a drought has reduced the population to 300, who must be transported to Earth. To raise the wind, he uses his advanced technological genius to patent groundbreaking new inventions. He also predicts a gigantic war, from which the Republican party will emerge as a global war-machine - unless the peaceful Antheans can stop them. It all goes belly up when Newton discovers alcohol, along with his first girlfriend, and is blinded by the CIA.



THE HITCHHIKER'S GUIDE TO THE GALAXY BY DOUGLAS ADAMS (1979)



As alien invasions go, it's fast, brutal and matter-of-fact. At the beginning of the novel, Arthur Dent awakes to discover that the Earth is on the verge of being destroyed by a fleet of Vogon "constructor" ships (resembling gigantic yellow bricks) in order to make way for a hyperspace bypass. Despite his protests, the ships circle the earth and annihilate it in a matter of seconds.



THE MIDWICH CUCKOOS BY JOHN WYNDHAM (1957)



The quiet, quintessentially English village of Midwich (in "Winshire" ) is invaded one day by some alien power. The alien force puts all the inhabitants to sleep and impregnates all of the women. The resulting children are blonde, golden-haired and inhuman. Not only do they have the power to impose their will on others, they can kill off any resistance to them. Gradually we discover that similar transformations have broken out across the globe, from Canada to Australia. But how can they be destroyed?



John Walsh



Star power: signs of life on Planet Hollywood

INDEPENDENCE DAY (1996)



Nasty green aliens, roaming the universe looking for planets to lay waste, stumble upon puny Earth, swiftly and meticulously destroying the White House and all the world's major cities. But they didn't bank on President Bill Pullman and his US-led coalition fighting back



SUPERMAN (1978)



Kal-El fell to Earth with superhuman strength and speed, the power of flight and the ability to shoot lasers from his eyes. Instead of ruling the world, he chooses to save it, invested with the strong moral sense of his surrogate parents, the Kents, and driven by his love for hard-nosed reporter Lois Lane.



ALIEN (1979)



Cultivated by the arms dealers of the future as the ultimate biological weapon, Ridley ScottÕs aliens had the troublesome habit of exploding from innocuous-looking eggs to plant embryos in the stomachs of well-known character actors, later causing a mess at the table when they burst from their hostsÕ bellies over dinner.



CLOSE ENCOUNTERS OF THE THIRD KIND (1977)



Those aliens that have been abducting fighter pilots and small children for the past half-century turn out to be friendly fellows after all, and boasting perfect pitch to boot. A departure from the evil alien template, Spielberg's little people with really big heads have become the quintessential extraterrestrials of the popular imagination.



ET (1982)



Stranded on Earth after his fellow alien botanists flee in a hurry, ET develops a psychic bond with Elliott, a lonely schoolkid. ET possesses supernatural abilities and is quite comfortable in drag, or the altogether. He finally gets to go home after making a long-distance phone call to his colleagues and evading the authorities on a levitating bicycle.



PREDATOR (1987)



Part of a sadistic and downright ugly race of aliens who visit Earth to hunt for human prey, the Predator finally destroys himself with the miniature nuclear device strapped to his wrist - but only after Governor Schwarzenegger has given him a darn good rumble in the jungle.



PLAN 9 FROM OUTER SPACE (1959)



Ed Wood is generally accepted to be the worst director ever to trouble Hollywood. Plan 9 From Outer Space is his greatest folly. In this horror/sci-fi genre blancmange, evil aliens implement their ninth plan for the invasion of Earth - resurrecting the dead as zombies.



MARS ATTACKS! (1996)



The bulbous-brained Martians in Mars Attacks! don't mess about, and they start decimating Tim Burton's stellar cast as soon as they touch down. Notable deaths include Jack Black, Michael J Fox and Danny DeVito, all incinerated by ray gun; Glenn Close, crushed by a falling chandelier; Jack Nicholson, impaled on a robotic arm; and Pierce Brosnan and Sarah Jessica Parker, killed in a clinch by a flying saucer crash.



THE DAY THE EARTH STOOD STILL (1951)



The peaceful alien Klaatu lands his flying saucer in a Washington, DC park to warn humanity of its own impending self-destruction. Naturally, the assembled American troops shoot him on sight, but Klaatu remains determined to bring peace to men on Earth, so he rises again to preach multilateral nuclear disarmament.



INVASION OF THE BODY SNATCHERS (1956)



The citizens of a small Californian town begin to suspect their friends and loved ones of being impostors, much to the consternation of local GP Miles Bennell. In fact, as Bennell discovers, the townspeople are being slowly replaced by aliens grown from sinister mangetout shaped pods, who kill humans before taking their form.


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