About 48 light years from us, coursing through space, is a blast of radio waves heading towards a distant globular star cluster.
Encoded in this radio signal is a message, written in the 1s and 0s of binary, transmitted from a giant radio telescope that once existed in the jungles of a blue planet orbiting a nondescript yellow star.
I refer, of course, to the Arecibo Message, a pictogram of humanity: what we’re made from, what we look like (roughly — the picture was a stick figure), where we can be found, how many of us there were in 1974 when the message was beamed into space, how we transmitted the message, and a blocky depiction of our Solar System that looks like it’s come from some ancient version of Minecraft.
The message’s destination, Messier 13, is located 22,000 light years away. If anybody’s living there, we’re going to have to wait 44,000 years for a reply.
The vastness of space means that interstellar communication is never going to be like making a quick phone call. Yet despite the daunting timespans, we’re not put off trying to contact whatever is out there. Since the Arecibo message there have been a handful of efforts to send messages to the stars, and now a team of scientists led by astrophysicist Jonathan Jiang from NASA’s Jet Propulsion Laboratory (JPL) in California, have joined the fray by creating a new message that they call the ‘Beacon in the Galaxy’.
Designing and transmitting messages into space falls into a field we call ‘METI’ — Messaging Extraterrestrial Intelligence. If SETI, the Search for Extraterrestrial Intelligence, is about passively and patiently watching for signs of life, then METI is the unruly sibling, determined to kick over anthills and find out if there’s any little green men hiding beneath.
It’s a hot topic, one that’s often controversial and divisive among the SETI community. For many years, METI’s main man was Russian radio astronomer Alexander Zaitsev, who launched four messages into space from the 70-meter Evpatoria radio dish in the Crimea. I remember, 12 years ago, attending a SETI conference hosted by the UK’s Royal Society in a manor house in the leafy Buckinghamshire countryside. Zaitsev made his case for transmitting, while the SETI Institute’s Seth Shostak (pro-METI) went head-to-head with the outspoken astronomer and science-fiction writer David Brin (anti-METI). Meanwhile other, calmer, voices tried to maintain decorum while still passionately arguing for or against transmitting.
The debate centers around what the consequences of making contact could be. Those pro-METI believe that contact would be hugely beneficial for humankind. Those cautious of advertising our existence to the Universe warn that we don’t know anything about what aliens might be like, or what unpredictable consequences our societies might face from interacting with them.
As a science journalist, I’m drawn to scientific disagreements like a moth to a flame, and the debate surrounding METI is one so fascinating that I even wrote a book about it. The Beacon in the Galaxy message is another opportunity to examine the various facets of this debate, so in April I spoke with Jiang and two of his colleagues, JPL’s Kristen Fahy and Stuart Taylor of the SETI Institute, to find out more.
Best Foot Forward
To be clear, the Beacon in the Galaxy has not yet been transmitted into space, nor are there any immediate plans to. The idea for now is to spark discussion and hone our interstellar-message-crafting skills.
“We want to send positive images, positive messages about humans into space,” says Jiang when I ask about his motivations for designing a message for aliens. He comes across as articulate and enthusiastic, a twinkle in his eye as he chats about how he sees the Beacon as condensing humanity’s better points into a short stanza of binary code.
This intrigues me from the outset. Although Jiang’s team have aimed to create a very basic message focused on scientific details, it feels to me that their intent is to subtly shape an aliens’ opinions about us — to present only a positive portrayal of humanity. The Beacon in the Galaxy is designed to give the impression that we are explorers interested only in science and knowledge, but if aliens could tune in to our television broadcasts, they’d get a different picture.
“We’ve been broadcasting a pretty bad representation of ourselves,” admits Taylor.
“We need to try and represent ourselves better.”
As Rebecca Charbonneau, a science historian at Harvard, comments when I ask her later about the Beacon in the Galaxy message, “[how to present ourselves] Is a problem SETI scientists have been tackling for decades.” She cites the example of the Voyager Golden Record, for which Carl Sagan and his team had to decide whether to provide an accurate picture of life on Earth, including all its horrors of war, poverty, discrimination and so on, or whether to tailor the contents of the record to only portray our best features. “They decided to pursue the latter, in part because they did not want to send what might be interpreted as a hostile message to the cosmos.”
Despite this intent to provide a sanitized presentation of humanity, the Beacon is not laden with messages and images of love and peace. It’s more abstract than that, because ET isn’t going to know our languages, understand our cultures, or even necessarily experience and interpret the Universe in quite the same way we do. So any successful interstellar message must first find common ground, and more often than not, METI approaches that through pure science. Concepts such as the quantum physical underpinnings of hydrogen atoms are universal across the cosmos, and so technological aliens should understand them, too.
Once that common ground has been ascertained, the message moves on to explaining concepts such as the biochemistry of life on Earth, and human DNA. There’s also a map.
“We want to send the message that we’re all citizens of the Earth,” Jiang tells me. “That’s why we included a world map. It tries to develop the message that everybody is equal, man or woman.”
To reiterate the point, the Beacon in the Galaxy also includes a modified version of Linda Salzman’s drawing of a nude man and woman that was originally etched onto the plaques attached to the Pioneer 10 and 11 space probes, which are now racing out of the Solar System having flown past Jupiter and Saturn in the 1970s. Back then, NASA was criticized by prudes for sending drawings of nudes into space, but there were also more pertinent concerns. Although not the intention, the two figures ended up looking Caucasian, and only the man’s hand was raised in greeting, making the female appear subservient at his side.
A few years later, when the drawings were included on the Voyager Golden Record, they were changed to show the woman’s hand raised in greeting, and the man’s hand lowered. Now, in the newly modified version in the Beacon to the Galaxy, both the man’s and the woman’s hand is raised.
Of course, what aliens would make of them is anyone’s guess — a raised hand in greeting is a human cultural affectation, and aliens might not even recognize the appendage as a hand.
“We want them to know what we look like,” explains Fahy when I mention these old criticisms of the drawings. “They might not decipher what they’re looking at, but it’s worth a shot.”
Jiang, though, has a more specific reason for including the drawings, saying that they are “to indicate how humans have two different sexes for reproduction.”
This prompts me to raise an eyebrow. The intention is a worthy one — to show that man and woman are equal. But I wonder, does it really tell ET how we reproduce? There’s no description of the act of reproduction, and would the aliens recognize the drawings as representing two different biological sexes? Indeed, alien reproduction may be quite different. For all we know, the aliens might have more than two sexes, or none at all.
I wonder if the Salzman drawings, however modified they are, have become sketches out of their time. The twenty-first century view on sex and gender is far more fluid than the conservative viewpoints of the past. Those who identify as non-binary and the trans community may have a difficult time seeing themselves in those drawings.
I ask Douglas Vakoch, President of an organization called METI International, to give his opinion of how the drawings relate to our modern viewpoints. “A twenty-first century depiction of gender diversity could be quite different from the Pioneer plaque,” he says.
Nevertheless, Vakoch acknowledges that communicating our human forms in such messages is difficult. “The pictures we send of ourselves may be the most difficult parts of the message to understand, but that doesn’t mean we should stop trying,” he says, echoing Fahy’s resolve.
METI International transmitted a message called Sónar Calling in 2018 that targeted the nearby exoplanet GJ 273b; they plan on beaming another message into space, from the Goonhilly Earth Station in Cornwall, UK, towards the TRAPPIST-1 system in October 2022. Both messages feature music as well as scientific information, and the Goonhilly message will detail our climate crisis, contrasting somewhat with the Beacon in the Galaxy by showing that perhaps not everything is rosy on Planet Earth.
Ones and Noughts
Like the Arecibo Message, the Beacon in the Galaxy is written in binary code, which Jiang believes is the mathematical system most likely to be understood by aliens.
“Binary, we think, is universal,” says Jiang. “It’s a language that can be understood by any intelligent being, and by a computer, because it’s just yes or no, true or false, 0 or 1. Our consciousness is the result of millions of years of yes and no combined together to make decisions. So binary is essential for communication with intelligence.”
Encoding a message in binary code is itself uncontroversial. After all, the Arecibo Message was transmitted in binary all those years ago. Vakoch wonders though whether binary encoding alone is enough to communicate the signal’s significance, or whether it’s also worth including geometric constructs such as pi and its relation to the circumference of a circle.
“There’s a serious problem in assuming that the use of binary code will, in and of itself, make mathematics intelligible,” he says. “It ignores one of the most important principles for creating meaningful messages: make the messages redundant. If aliens don’t understand one formulation of our math or science, they might recognize another.”
Jiang’s team argue that the message doesn’t need to include geometric concepts because they see geometry as “a logical progression from more basic concepts of mathematics” and that their inclusion would only lengthen the message with content that the aliens likely already know.
Vakoch, though, thinks that we need to let our interstellar messages breathe, to have space to include more information in case our assumptions about what aliens understand is incorrect.
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“I can just imagine, after months of trying to make sense of our math, one alien pointing at part of the message and saying to their colleague, ‘I think that’s supposed to be a circle. And they seem to know that there’s a precise relationship between the distance around the circle and its radius’,” he says. “How unfortunate it would be if we skimped on our geometry tutorial, when it might be just what’s needed to establish common ground.”
Beyond these debate points, the Beacon in the Galaxy message does contain a lot of cool concepts, such as the way it time-stamps itself — in other words, lets the receiver know when, in a cosmic context, the message was transmitted.
Telling aliens that the message was beamed in the Earth-year 2022 isn’t going to be all that informative — seconds, minutes, hours, days, years, these are all human constructs native to our planet. So the message needs a universal time-keeper, and they found it in the quantum behavior of hydrogen atoms. When a hydrogen atom changes its quantum spin — a process known as the ‘spin-flip transition’ — it emits radio waves with a precise wavelength of 21.106114054160cm, which is recognizable to astronomers as the 21cm neutral hydrogen line that radio telescopes routinely observe. This can also be expressed as a frequency, 1.4204 billion periods per second (more recognizable to us as 1420MHz), and this can be broken down further, to give a base unit of time: 70.403 billionths of a second for each period. Jiang’s team then count how many of these base units of time have passed since the Big Bang, and the message will then include that figure to indicate when it was sent.
There is a bit of a problem, in that we do not know, down to the second, when the Big Bang occurred. “Usually we would want a clock with a precisely defined starting point,” says Vakoch. “In this case, the starting point of the cosmic clock is zero, give or take 20 million years.”
Now that Arecibo has collapsed, and Western astronomers are unlikely to be able to use the Yevpatoria radio transmitter in the Crimea anytime soon, how can the Beacon in the Galaxy be beamed to the stars? Jiang’s team suggest that either China’s Five-hundred-meter Aperture Spherical Telescope (FAST), or the SETI Institute’s Allen Telescope Array of 42 dishes, could be modified and turned into transmitters.
The Great Transmission Debate
The Beacon in the Galaxy has reignited the debate about whether humanity should be transmitting into the cosmos. Taylor, however, doesn’t think that’s a bad thing. He suggests it might prompt us to reconsider our place in the cosmos, our likelihood of surviving into the deep future, and what we might learn from any extraterrestrial civilizations we contact.
To enter the debate they’ll need a thick skin. As I’ve witnessed myself, those discussions can quickly become fraught, but Jiang’s team are confident that transmitting our presence into deep space for whomever lurks there isn’t only safe, but is the right thing to do on behalf of humanity.
“We’ve been sending out radio signals for the past 100 years,” says Fahy. “If there is a civilization so technologically advanced that they can travel to Earth and potentially annihilate us, then they probably know about us already.”
Hmm. This is a well known fact, oft repeated as rationale for doing METI. Ipso facto, if they already know we’re here, then sending deliberate messages can’t be any more dangerous.
Except that if you dig a little deeper, it doesn’t appear so clear cut.
Radio waves, like all electromagnetic radiation, lose power with distance by the inverse square law. The light from the Sun is 16 times weaker on a planet four times as far from the Sun as Earth. So by the time our radio signals reach interstellar distances, they’re extremely faint, particularly TV signals that aren’t exactly being blasted into space by powerful transmitters. The SETI Institute’s Seth Shostak has shown that an Arecibo-sized radio telescope could not detect our TV and radio leakage even at the distance of Proxima Centauri, the nearest star to the Sun, at 4.2 light years away.
To quantify things further, in 2011 Jim Benford and John Billingham showed that the message content of a transmission from a typical terrestrial radio telescope, such as the 70-meter Yevpatoria dish, would only be detectable by a similar-sized receiver out to a distance of just three light years, while the raw radio energy of the message would be detectable out to 108 light years. Scale that up to a transmitter and receiver the size of the Square Kilometer Array, and the ranges increase to just 19 and 648 light years, respectively. And what of the Arecibo message — how far away could another Arecibo detect it? It seems that nobody can agree on this — Frank Drake has suggested it would have a range of 25,000 light years, far enough to be detected at M13. H. Paul Shuch, of the SETI League, called this the ‘Arecibo Myth’, and said that it would have a range of just 10,000 light years. Shostak is even more pessimistic, and calculates that one Arecibo could detect another Arecibo out to a distance of 400 light years, and no farther.
All of which calls into question the likelihood anyone out there knows we’re here.
It’s not impossible, though. If the aliens have a radio telescope the size of, say, a small moon, then they are going to be able to detect fainter signals from farther away, including our messages and leakage. That’s a big ‘if’, however. Radio telescopes are not free — they cost energy to run, and Jim Benford has calculated that a Chicago-sized radio telescope would cost a lot of energy, equivalent to $70 trillion US dollars in human terms. Plus, I would ask, to what end would aliens have need of such an unfeasibly large telescope? Why, to be able to hear our faint signals, of course! But if they already know we’re here, then why do we need to message them? If they want to get in touch, they will — we wouldn’t need to prompt them.
But Jiang reminds me of the motivation behind the Beacon in the Galaxy. “Humans are still selfish, still fight wars, still behave like children, so we want to send positive images,” he says. It’s a charm offensive for aliens who may have already formed a negative opinion about us in the unlikely event they’ve picked up our television signals.
That mindset makes the assumption that these aliens will be virtuous. It’s an opinion that Jiang can get behind. “If any civilizations can live long enough, and are able to reach the stars and us, then we think that they will not behave like kids anymore,” he tells me. “They will have survived, and surviving means being at peace for millions of years. So we don’t think anybody who is able to travel to the stars is dangerous.”
The overwhelming likelihood is that ET will be far older than we are, potentially by millions or even billions of years, because we’re new on the scene and there’s been plenty of time for other species to evolve in the Universe. So the language of SETI has often been about communicating with ‘higher powers’ far older than we humans. Carl Sagan used this argument to persuade the Democratic Senator William Proxmire to support SETI, when he pointed out that ET could teach us how to avoid nuclear armageddon, as they must surely have done to have survived for so long.
“We have to consider that we may need to be rescued,” says Taylor.
It’s a concept that echoes the eco-themed message to be transmitted from Goonhilly. “If they are more like our modern, progressive, liberal democratic free-world society, then I think they will be more likely to help us,” he adds. “So, by receiving a message, we can learn how to survive.”
I wonder if this is describing a true picture of how Western society operates in relation to the rest of the world, or if it’s more of a fairy tale. Don’t get me wrong, there are many truly wonderful, generous people who freely give advice and resources to help others, but governments tend not to, at least not without strings attached. I’m not sure I want humanity to become indebted to an extraterrestrial civilization.
Charbonneau says that human history also tells us otherwise. “It is arrogant folly to assume that Western civilization, with all its historical horrors, would be the standard for intelligent civilizations,” she says. Furthermore, SETI researchers in general should be wary of conflating advanced technology with advanced ethics. After all, some of the most technologically-advanced human civilizations of history have committed unspeakable horrors: the Roman Empire, Imperial Britain, the Nazis in World War Two. “I think it is quite naive to believe that alien civilizations would be ‘more progressive’ than human society,” says Charbonneau. “This falls into the trap of believing that progress moves in a line, from worse to better. We certainly shouldn’t equate technological achievements with moral ones.”
Charbonneau actually thinks creating interstellar messages is a good idea, since the chances of aliens actually detecting them are very slim, but we can learn a lot about ourselves in the process — by figuring out what we want to say about ourselves, why we want to say it, and who gets to say it. Interstellar-message design is still at a very early stage, and we’re bound to make mis-steps along the way. What is required to make progress is discussion, not just among western SETI scientists, but among people from all backgrounds all across the world, so that our interstellar messages can become more representative of who we all are.
“We encourage discussions,” agrees Jiang. “We should discuss this as citizens of the Earth. We don’t want to transmit this message in secret. We want to discuss this openly.”
And we have time. Assuming that aliens are not already here, then distance protects us. “It’s not like we’ll be texting them back and forth,” says Fahy. “It would last generations, hundreds of thousands of years. So that should decrease the fear that we’re broadcasting too much or receiving messages from them that would negatively impact our planet.”
“It’s something in our distant future,” admits Jiang. “Our children’s children’s children’s children may get lucky.”
Let’s hope that when that day comes, they don’t regret their ‘luck’.