The Why of METI and SETI

by Paul Gilster on September 18, 2009

by Larry Klaes

About a decade ago while attending a SETI conference, I was listening to a researcher give a talk about detecting messages from other galaxies such as the giant elliptical galaxy Messier 87 and the immense Virgo galactic cluster it resides in. Since M87 is about 60 million light years from the Milky Way, I later asked him why would someone send a message that they could not hope to get a reply to for 120 million years at the least.


His reply was rather vague and dissatisfying to me. It was along the lines of they would do it for the sake of being able to sending such a message across such a vast distance and time. I was left with the impression he did not fully think out why any intelligence would send messages across millions of light years of intergalactic space with even less hope of a reply than our token METI (Messaging ExtraTerrestrial Intelligence) effort with Messier 13 in 1974 via Arecibo, for which we will need to wait 50,000 years for the quickest reply from there if ever.

Image: Messier 13, a globular cluster containing roughly one million stars in the halo of the Milky Way. It lies in the constellation Hercules, 25,000 light years from the Sun. Credit: Robert Lupton, Sloan Digital Sky Survey).

The SETI researcher seemed focused on the mechanics of how such a message would be done, which is good in itself of course, but not the why of it, which for me is the entire key of whether such transmissions will ever take place or not. Setting aside funding and resources for a moment, no serious science project is going to happen unless you give those in control of such things a reason for doing so that is agreeable to them.

Look at the Apollo manned lunar project conducted by the United States in the 1960s. If it were not for the underlying major goal of the two main Cold War nations trying to best each other via space, it is more than likely we would still be talking about sending humans to the Moon some day in the future. Just look at how we haven’t left LEO in person since late 1972 because of changes in the geopolitical climate.

Later on at the same conference I talked with some other SETI scientists about a METI type of idea that had intrigued me since I read author James Gunn’s 1972 SF novel The Listeners, where a civilization circling the star Capella sends humanity all its knowledge because its sun is going to explode and they know they cannot escape it otherwise (at the very end of the novel, it is revealed that a similar broadcast is also on its way to Earth from the region of the Crab Nebula, the remnants of the famous supernova of 1054 CE).

This made sense to me, as a sophisticated culture would not want to die off in vain and disappear completely from existence. They also would have nothing to fear or lose from signaling the rest of the galaxy about themselves. Not only would they remain alive in their records and the memories of others, but perhaps their knowledge might even enlighten and enrich their neighbors. And they wouldn’t be around if the recipients weren’t friendly in any event.

DNA radiotelescope

Image: Even a description of DNA could be sent to the stars. Art by Jon Lomberg (from the collection of Frank Drake).

I brought up this idea to these SETI folks, who surprisingly dismissed it out of hand. Maybe some things have changed in the last ten years, but I got the distinct impression that at least some of those who work in SETI thought that aliens would contact us purely for the good of increasing scientific knowledge. Or as I said above, the focus from these researchers seemed to be on the methods of interstellar (and intergalactic) signaling, not the potential range of reasons behind it, which is no small factor here.

Maybe there are such enlightened and altruistic societies out there with only those pure motives in mind. Certainly I am taking educated guesses here as much as anyone else from this planet. But just as Apollo happened mainly to showcase international and ideological might with science taking a backseat despite how NASA presented things, I am willing to bet that any alien species, even an insane one, will be conducting such a major undertaking as a sustained METI effort with more than one motive in mind. Certainly these motivations will include improving the various situations for the signalers.


Thus my desire to focus on delving into *why* any race of beings might want to conduct METI, especially one designed to last for many years and cover much of the galaxy, which would make sense if you don’t know who your neighbors are and you want to make sure to hit as many potential targets as possible. As a bonus for humanity, figuring out why an intelligence might want to signal us will help narrow our search in that very big celestial haystack out there, saving our SETI projects money, time, and resources in the process.

Image: The Evpatoria radio telescope in the Crimea, from which several METI signals have been sent to the stars.

The following is a short list of ideas I have created to consolidate my thoughts on why an alien intelligence would conduct their own METI program. It is certainly not meant to be complete and other ideas are welcome.

1. An ETI signal is intercepted by humanity by mistake. This would be an ETI message aimed our way by accident that was intended for someone else. Obviously, this one could come from anywhere at any time.

2. A “stunt” message, just like certain groups of humans have been doing lately by broadcasting Beatles songs, Doritos advertisements, and personal messages towards nearby star systems. I would even put the possibility of a practical joke in here, as some aliens may be as big a bunch of wiseasses as we are. Note how often humor is left out of the equation when considering the motives and behaviors of other intelligences. Why can’t they laugh about the absurd as much as we do? It may be not only a sign of intelligence but also a survival mechanism in this often bizarre and frequently dangerous Universe.

These messages could come from just about anywhere, but they have the serious drawback of being of very short duration. Only recently have we started more than a handful of consistent SETI programs, and even they are limited to a few electromagnetic realms and often with numerous gaps in data gathering time.

3. A deliberate “ping” to get our attention to open up a dialogue and information exchange. This can range from sheer scientific curiosity to the need for something they don’t have but we do (Nachos?). They may also be doing this for darker motives, from seeing who is out there to convert, conquer, colonize, or outright destroy. After all, if one species can colonize the whole Milky Way galaxy in just a few million years as has been asserted, others may find that to be a very legitimate threat to their existence and want to stop such a problem in advance.

I would like to think that 400 billion star systems across 100,000 light years of space should be room and resources for lots of beings – but when did logic ever play into certain motives when it comes to survival?

I have always always been a bit skeptical of the idea pushed by Carl Sagan about advanced intelligences broadcasting the equivalent of the Encyclopedia Galactica around the Cosmos to anyone who might want it. No one in their right mind goes around sharing every detail and secret of their lives with unknown and unpredictable strangers, so why would even an advanced species want to share their knowledge and power with potential rivals? Plus as SF author David Brin has pointed out, information unique to us may be our one bargaining chip with alien societies and we would not want to give it away for free.

4. A flood of information from a society that knows it is going to be destroyed not only as a species but their knowledge and works, too (see above). Having little to lose or fear from their information being used against them, these ETI send us and others all that they know to preserve themselves at least in data form.

This is one legit reason for SETI to aim its instruments at novae, supernovae, hypernovae, and GRBs, along with red giants, white dwarfs, pulsars, and even black holes. Supernovae are also important to check out for signals from non-threatened ETI who might use them as natural cosmic beacons.

5. Really advanced beings might signal us to say things like “Hey, we’re the big guys on the block – don’t even think about messing with us” to “We need your solar system for our latest Dyson Shell Galactic Mind Expansion Project, thanks ever so much” to “Hey, Charlie, we found some more vermin over here – get the Raid!” These guys might be found around the galactic core, in globular clusters, around black holes, or way out in the very cold fringes of the galactic edge.

To be honest I think we will have a better chance of finding them by their infrared signatures or astroengineering structures, as I don’t know if such beings would ever bother talking to us, but obviously I could be wrong. They might message us just because they know they can and cannot be harmed by us. People have been known to poke a stick in an ant colony just to see how the little insects will react.


Of course, G class stars with exoplanets where the Jovian-type worlds are not orbiting their suns in a matter of mere days and could therefore have Earthlike worlds (or habitable exomoons orbiting any Jupiter-type exoplanets) are potentially good bets too. And we might have beings exploring or colonizing all kinds of other star systems such as red dwarfs, but whether they would be doing METI as well is another matter.

Image: The Arecibo radio observatory in Puerto Rico. It was during the dedication of this facility that a message toward the globular cluster M13 was sent. Credit: SETI Institute.

Now there have been a number of legitimate METI projects over the years emanating from Earth that were not just stunts. A list of these efforts may be found at the Wikipedia entry on Active SETI. While these information messages were put together with some thought and planning and were sent out using powerful radio telescopes, they still suffer from being relatively brief in duration and therefore have limited chances of being picked up by unsuspecting (and hypothetical) alien species.

As one example, the Arecibo Message of 1974 to Messier 13 was just three minutes long. What are the odds that even if there are a fair number of suitable ETI living in that globular star cluster 25,000 years from now that even one of them will just happen to detect that transmission as it zips along? Not even the “covert” 20-minute METI effort by Joe Davis of MIT in the early 1980s has much better odds of being detected in the Milky Way. More recent METI broadcasts have all been narrowly focused and capable of being received by relatively few stars.

The shortness of these METI efforts is why I left them off the list but wanted to mention them just the same. ETI could be doing similar such broadcasts, but the odds of our detecting them with our current SETI programs are slim. Thus our chances lie with the sustained METI programs, which as has been pointed out already, may have some very interesting reasons behind their existence.


ljk February 3, 2010 at 1:38 1/29/10:

“Is calling E.T. a smart move?”


“As the citizens of Planet Earth strive ever more enthusiastically to reach
E.T., some experts say numerous messages zipping through the cosmos are
confusing or little more than space spam.

Others ask who has the right to represent our world to the galaxy — or
question the wisdom of bellowing out our presence in what may be a hostile

‘A lot of the stuff is very responsible, but I do wonder about some of the
other stuff that’s being transmitted,’ Albert Harrison, a professor of
social psychology at the University of California at Davis, said at a
conference at the Royal Society in London on Monday.

‘There’s pictures of celebrities, of two political candidates — one
identified as good, the other identified as evil — snack-food commercials,
love letters to rock stars and so on.’

He added: ‘When you start broadcasting and drawing attention to yourself,
you have to be very cautious about the image you give. We might appear as a
threat to them.

‘We don’t know what will be made of these messages and it could be years and
years before we find out.’”


“… British cosmologist Stephen Hawking … suggests ‘we should keep our
heads low,’ given any possibility of encountering a hostile, technologically
superior civilisation.

‘The risk posed by active SETI is real,’ the prestigious British journal
Nature warned in 2006, in an editorial that unleashed divisions among
enthusiasts as to who had the right to be ambassador of Earth.”

The rest:

ljk February 9, 2010 at 23:50

Calling ET: Your chance to send a message to alien life

To mark 50 years since the launch of the SETI – Search for Extraterrestrial Intelligence – programme, it’s your chance to write a message that will be radioed into space.

By Robert Colvile

Published: 7:00AM GMT 09 Feb 2010

To quote:

“Yet given that it will take this message in a celestial bottle 40,000 years to reach another planetary system, it seems most sensible to send signals by radio – which is where you come in. To mark the SETI anniversary, as well as the publication of Paul Davies’s The Eerie Silence, a new book about our search for extraterrestrial life, Penguin UK and National Science and Engineering Week will be firing off up to 5,000 messages into space via a radio telescope. The messages can be up to 40 words, and can say anything you like – greetings, warnings, confessions, jokes. The 50 best will be revealed in The Daily Telegraph in March, with each of the winners receiving a copy of Davies’s book. ”

Full article here:

ljk January 31, 2011 at 4:26

A Protocol for Messaging to Extraterrestrial Intelligence

Authors: Dimitra Atri, Julia DeMarines, Jacob Haqq-Misra

(Submitted on 25 Jan 2011)

Abstract: Messaging to extraterrestrial intelligence (METI) is a branch of study concerned with constructing and broadcasting a message toward habitable planets. Since the Arecibo message of 1974, the handful of METI broadcasts have increased in content and complexity, but the lack of an established protocol has produced unorganized or cryptic messages that could be difficult to interpret.

Here we outline the development of a self-consistent protocol for messaging to extraterrestrial intelligence that provides constraints and guidelines for the construction of a message in order to maximize the probability that the message effectively communicates.

A METI protocol considers several factors including signal encoding, message length, information content, anthropocentrism, transmission method, and transmission periodicity. Once developed, the protocol will be released for testing on different human groups worldwide and across cultural boundaries. An effective message to extraterrestrials should at least be understandable by humans, and releasing the protocol for testing will allow us to improve the protocol and develop potential messages.

Through an interactive website, users across the world will be able to create and exchange messages that follow the protocol in order to discover the types of messages better suited for cross-cultural communication. The development of a METI protocol will serve to improve the quality of messages to extraterrestrials, foster international collaboration, and extend astrobiology outreach to the public.

Comments: Accepted for publication in Space Policy

Subjects: Popular Physics (physics.pop-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Cite as: arXiv:1101.4968v1 [physics.pop-ph]

Submission history

From: Dimitra Atri [view email]

[v1] Tue, 25 Jan 2011 22:30:08 GMT (162kb)

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