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SETI: Terminating
the transmission

Posted: 4 May 2010

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If you’re a typically shy and reserved character, you’ll know how difficult it is to go into a party full of strangers and strike up a conversation. Thoughts race through your mind: who are these people? Will they like me? Will anything I say to them sound sensible? Who are the people I should avoid, and who are the friendly folk that I’d like to get to know?

If you’re bold, you’ll dive straight in and maybe make some new friends, or find some new enemies along the way. If you’re reticent, you’ll hover around the edges of the champagne reception, picking up little snippets of conversation floating your way but never really joining in. You might not make any new friends, but at least you won’t get yourself into any trouble.

Messaging Extraterrestrial Intelligence (METI, sometimes called Active SETI), is much like diving into the party and making your presence felt. In part 1 we encountered Dr Alexander Zaitsev of the Russian Academy of Science in Moscow, who is attempting to take Earth into the party by transmitting messages to nearby stars that he hopes harbour intelligent beings. However, his efforts have been met with stiff resistance from some quarters; a core group of SETI scientists forcefully argue that we should not be shouting into the jungle, that we shouldn’t be looking to strike up a conversation with strangers whose motivations and capabilities are completely unknown to us.

Should we really be trying to reach out to our neighbours in the Galaxy? Image: NASA/ERSA/K Kuntz (JHU)/F Bresolin (Uni of Hawaii)/J Trauger (JPL)/J Mould (NOAO)/YH Chue (Uni of Illinois)/STScI/CFHT/JC Cuillandre/Coelum/G Jacoby/B Bohannan/M Hanna/AURA/NSF.

One of the biggest dissenters is the scientist and science fiction author Dr David Brin []. In 1989 the International Academy of Astronautics SETI Panel, chaired by former diplomat Michael Michaud, drafted SETI’s First Protocol, which describes the procedures that should follow were we to receive an extraterrestrial signal. The Protocol states that “no transmission in response to a signal or other evidence of extraterrestrial intelligence should be sent until appropriate international consultations have taken place”.

However, in 2007 Michaud and senior SETI researcher John Billingham of the SETI Institute resigned from the panel, over what they describe as backtracking by the committee on a Second Protocol that would allow any individuals to beam messages into space in the hope that aliens will receive them. For Brin, who was involved in the drafting of the Second Protocol until the split, the question is very simple: what right do individuals like Alexander Zaitsev have to speak for Earth without prior consultation?

“Our main objection is not so much against Active SETI in its own right,” Brin tells Astronomy Now. “Rather, it is the behaviour of a very small, insular community of individuals who are pursuing an activity that might profoundly alter human destiny, without first bothering to discuss it with their scientific peers or with the public.”

Anthropologist Dr Kathryn Denning of the University of York in Toronto, Canada, likens the METI dilemma to sociologist Garrett Hardin’s ‘Tragedy of the Commons’, which uses the analogy of overbreeding on a village commons to help frame traditional global problems such as pollution, overpopulation, nuclear arms control and, now, METI. The Tragedy of the Commons is an attempt to assess at what point individual rights begin to harm the shared resources of the many; if any given herdsman adds one extra animal to his herd then he will gain maximum benefit from it when he sells the animal, but the overbreeding produces a negative effect that has to be shared by all the herdsmen. This conflict between individual rights and the shared resource of Earth’s security is exactly what David Brin is alluding to. Yet it’s not a perfect analogy. We know what overpopulation, runaway nuclear proliferation or climate change will do to Earth, but we have no idea what effect initiating contact with ET will have. It could just as easily benefit everyone on Earth as it could bring disaster upon us all – we just don’t know, and therein lies the dilemma.

The 70-metre Evpatoria radio telescope, from where several interstellar messages have been transmitted. Image: S Korotkiy.

Some scientists suggest that advanced extraterrestrials must be altruistic with parental tendencies towards younger species such as our own. How else could their own society have survived for so long if they were warlike? For Brin, the assumption that aliens might be friendly is an assumption with no basis in evidence. Even Frank Drake, who favours the altruistic hypothesis, cautions that altruism is in the eye of the beholder, and actions that appear perfectly moral to ET may seem abhorrent to us, or vice versa. Altruism seems to be a malleable concept, defined differently by any given culture, rather than being a universal constant – take bears’ tendencies towards infanticide, for instance. However cruel this seems to us, it must seem perfectly reasonable to the bear. The idea that just because a civilisation is advanced that it therefore must be altruistic just doesn’t hold up to scrutiny according to Professor Nick Bostrom, the Director of the Future of Humanity Institute in the Faculty of Philosophy at the University of Oxford.

“I think that some people look at human history and think of ourselves as having advanced morally,” says Bostrom. “But even if one could detect such a pattern of increasing moral enlightenment in human history, it would be hazardous to extrapolate that into our future, but I imagine that kind of argument would underpin some people’s optimism about technologically advanced civilisations.”

Even if ET is friendly, their civilisation may be so superior to our own that any contact between us, however good-natured, could negatively affect our own civilisation.

“Let’s recall that participants in past ‘first contact’ events between human cultures had their own close-held sets of basic assumptions, all of which proved devastatingly harmful and wrong,” says Brin. “Claiming that ‘this time things are different and we know what we are doing’ is arrant temporal chauvinism, the very last trait that should be shown by people whose project aims to span space, time and culture.”

History, however, is tainted by myth, inaccuracy and rampant speculation. We picture in our mind’s eye European colonists wreaking havoc across the Americas, the Conquistadors putting the likes of the Aztecs, the Mayans and the Incas to the sword. While there was undoubtedly plenty of pillaging going on, that’s not what caused the ancient civilisations of South America to fall, points out Denning.

“Yes, contact has often gone badly for one side and better for the other, but it is not often such a straightforward ‘winners and losers’ game,” she says. “It is rarely ideas and technology that destroy one side – it is usually infectious disease.” Hitching a ride with the Europeans were diseases against which the native Americans had no immunity. Smallpox wiped out the Aztec army, their Emperor, and 25 percent of their population. Between 60 and 90 percent of the Inca population died from it. Between 1492, when Columbus found the shores of the New World, and 1650, the native population of the Americas fell from an estimated 50 million to just eight million, mostly from disease. And it wasn’t just people. ‘Alien’ plants and animals were introduced into the Americas, which disturbed the local ecology, destroying food chains. According to Denning, history suggests that as long as aliens don’t turn up in a spaceship carrying their diseases and pot plants with them, we should be relatively safe.

In visual range
It all seems to be a somewhat messy debate of anthropology and philosophy. What do SETI scientists, mostly radio astronomers by training, make of it?

“My personal take on this is that Earthlings are a primitive civilisation, we are still killing each other, and maybe we should just be doing passive searches, and not doing active SETI,” says Dr Dan Werthimer of the University of California, Berkeley, one of the prime movers behind SETI@home and optical SETI research. “My guess is that advanced civilisations are going to be peaceful and want to help us, but that’s just a guess.”

On the other hand, the UK’s Dr Alan Penny of the University of St Andrews is all for attempting to contact ET, and dismisses the dangers. “If they can harm us, that means they can come here and would know about us already,” he says. “If they can come here, then they have already come here, and there’s a ‘Death Star’ in the asteroid belt just waiting for the right moment. Maybe sending a signal out might trigger the Death Star, but maybe actually not sending the signal out might trigger the Death Star.”

The planets around the star HR 8799, imaged using the ten-metre Keck Telescope on Mauna Kea in Hawaii. The star has been masked by a coronagraph. Image: C Marois et al/NRC Canada.

Far-fetched hypotheticals of ‘beserker’ probes don’t keep Penny awake at night, nor do they seem to give many of the public nightmares. In a poll on the SETI@home website in 2005, seventy percent of those who voted favoured the idea of sending a signal that aliens might hear. In an impromptu poll during an Internet lecture in March 2010 for the Institute of Physics by Professor Paul Davies of the University of Arizona, 72 percent favoured the idea of METI.

Besides, Alan Penny makes a valid point. Any technologically advanced civilisation within a 100 light years, or perhaps more, will have the ability to detect us if they want to, and our visibility has nothing to do with our radio emissions. Yes, powerful planetary radar used in mapping other worlds in the Solar System is making Earth much brighter at microwave wavelengths, so much so that to Zaitsev they make a mockery of any attempt to ban METI. Our television signals, however, are much less effective despite popular impressions that the inhabitants of Pollux are currently tuning into episodes of Mork and Mindy – the SETI Institute’s Dr Seth Shostak has shown that television signals begin to fade into the background radio static beyond about a light year away, although highly sensitive detectors could still potentially pick them up. Most damning though is the simple fact that any advanced aliens relatively nearby that are curious enough to look for us will surely be able to see us.

In late 2008 the Hubble Space Telescope produced an image –albeit a speck of light – of a planet three times the mass of Jupiter orbiting the star Fomalhaut, while the ten-metre Keck Telescopes atop Mauna Kea in Hawaii imaged three planets up to ten times the mass of Jupiter around the star HR 8799, and an eight-Jupiter mass planet orbiting beta Pictoris was captured by the adaptive optics on the European Southern Observatory’s Very Large Telescope. Each of these planets is very young and very warm, glowing bright enough to be seen, but the real technical obstacle was being able to negate the contrast ratio between the host star and the planet, which was overcome through use of a coronagraph to block the glare of the starlight. Writing in the 12 April 2007 edition of Nature, John Trauger and Wesley Traub of NASA’s Jet Propulsion Laboratory suggest that Earth-like worlds in planetary habitable zones would be ten billion times fainter than their host star with an angular separation of 0.1 arcseconds or less, but despite this a space-borne telescope with a sophisticated coronagraph could image and spectrally analyse ‘Earth’s twin’ around another star. Furthermore, the next generation of extremely large telescopes, ranging from 30 to 100 metres across, should have sufficient light grasp to image Earth-like planets. There’s no reason why an advanced ET civilisation could not already have this capability, and have used it to have discovered our planet long ago. The Hubble and Spitzer space telescopes have measured the presence of carbon dioxide, carbon monoxide, methane and water vapour in the atmosphere of the gas giant exoplanet HD 189733b twenty light years away. Aliens within at least 100 light years would be able to see that our atmosphere contains a large concentration of pollutants and conclude that there is an industrial society living on it. Our secret would be out.

The areas of the sky that have been illuminated by powerful, narrow-beam planetary radar. Image: A Zaitsev.

On the other hand, the numbers don’t work in favour of current METI projects, and the odds are that any signals we send will fall on deaf ears. Even if Frank Drake’s estimate of 10,000 civilisations in the Milky Way Galaxy holds water, that still means on average we have to send messages to 2.5 million stars before we reach even one civilisation. Furthermore, beaming out messages for a few hours is not enough. The Galaxy is about 12 billion years old, and the chances that there are many independent civilisations all around at the same time is slim – we may have to wait millions of years for another advanced civilisation to pop up and hear our signals. “It’s no good sending out a signal for ten minutes, or ten hours, but our civilisation is not set up to conduct a million-year programme,” says Alan Penny.

Zaitsev’s efforts are therefore only a start, the very tip of an iceberg that could stretch far into the mists of the distant future. There’s a strong argument that it would be more efficient if we held our breath and saved our resources rather than firing blindly into the night. As Seth Shostak says, “Let the aliens do the heavy lifting.” And that’s music to the ears of those who advocate a hush-hush policy. Of course, Alexander Zaitsev’s argument is that nobody is transmitting, and consequently we find ourselves in a catch-22 situation.

You may wonder why the likes of David Brin are so upset about transmitting now, given the tiny chances of success any time soon, but there’s something else that bothers him. It’s not just the act of transmitting that worries him, but the content of those messages.

By comparison, only a few small points on the sky have been targeted for interstellar transmissions. Image: A Zaitsev.

Think of how difficult it must be to find a birthday present for someone as rich as Bill Gates. Now think how difficult it will be for us to offer something of value to a civilisation that is thousands, maybe even millions of years ahead of us. Our science and technology will, to them, seem as outdated as the abacus. What else could we offer them? Our culture and history are our only bargaining chips, says Brin; giving them up to the stars free of charge puts us at a disadvantage when the aliens turn around and ask for something. One imagines that Brin would bristle at Seth Shostak’s idea of simply emptying the Google servers into the nearest transmitter and beaming it all into space.

So, are we any closer to figuring out who gets the right to decide who speaks for Earth? Radio astronomers involved in SETI are perhaps not the best choice to assess the risks because they have most to gain from continuing the experiment, leading to an inevitable conflict of interest. Opening up the discussion would sound like the wisest choice, but that could lead to too many voices all saying different things, and whatever course of action is chosen is going to upset some people. There’s no simple answer, says Nick Bostrom, other than to wait.

“If we don’t send any signals now, we can change our minds later and send signals, but if we signal now, we cannot take them back,” says Nick Bostrom. “That would suggest that the safe and conservative option is to refrain, at least for the time being, and wait until much more analysis has been done.”

It would seem that which side of the fence you fall on in the great transmission debate depends on whether you believe ET will inevitably by friendly, trustworthy and helpful, or whether you feel there’s no evidence whatsoever to base assumptions of ET’s benevolence (or malevolence) on. Even the great Carl Sagan, who was one of the first to foster the idea of wise, benevolent aliens who would bequeath to us all their great knowledge, recommended that we should do a little bit of reconnaissance and find out more about the Universe before attempting to contact anyone – assuming there is anyone out there to contact in the first place, of course. We may all be arguing over nothing, and the rest of the Galaxy may be as barren as a desert. But, as long as hope remains in the search for extraterrestrial intelligence, dreams of communicating with people from another world will always capture our imagination.

Do you agree with the principles of METI, or do you side with those who believe it is risky? Write to us at web2010(at) and express your opinion.

Stay tuned throughout April for more SETI articles.

Find out more
Nick Bostrom’s website:

David Brin’s website:

Kathryn Denning’s website:

The case for METI:

The case against METI:

SETI’s First Protocol: