It was a humid day in November of 1974 when the Arecibo radio telescope in Puerto Rico made history.
At a ceremony to celebrate the site’s powerful new antenna, a group of dignitaries gathered to witness to its maiden broadcast.
Among them was the astronomer Frank Drake, who’d worked with Carl Sagan to write the message Arecibo was about to beam out.
Now, as the assembled visitors fell silent, Drake could hear the sound of his work being broadcast. A loud, alternating hum that seemed to fill the Puerto Rican countryside.
The broadcast lasted three minutes. By the end, people were in tears, overwhelmed with the enormity of what they’d just done.
That’s because the message Arecibo sent that day wasn’t a regular transmission.
Rather than anywhere on Earth, it’s target was Messier 13 – an impossibly distant cluster of stars in a patch of the universe we call Hercules. And it’s intended audience wasn’t other humans.
For a month prior, Frank Drake had been refining his broadcast so it could be understood and decoded by alien intelligences. By aliens who might inhabit a planet circling one of the M13 cluster’s stars.
It was the first serious attempt in human history to message an extraterrestrial civilization.
Incredibly, it wouldn’t be the last.
Although Frank Drake had the distinction of writing the first serious interstellar message, he was far from unique in his desire to contact ET.
Back in the 19th Century, Carl Gauss suggested cutting down swathes of forest to make geometric shapes that could be seen from the Moon; while the astronomer Joseph von Littrow went one further – suggesting we dig vast kerosene channels in the Sahra and set them ablaze to try and attract the attention of Martians.
Closer to Drake’s time, the Soviet Union had beamed a radio message at Venus – one consisting of the words “peace”, “Lenin”, and “USSR”.
But Drake was the first person to really sit down and think about how to communicate with intelligences who wouldn’t recognize human languages, who would have no idea who Lenin was, and who might mistake the word “peace” for “we are extremely tasty, please come eat us.”
The result? The Arecibo Message.
Seen today, Drake’s message looks like a bunch of blocky figures ripped from some terrible retro arcade game.
But scratch the simple surface, and its genius becomes apparent.
With a predetermined 3 minute transmission to work with, one which could broadcast only 10 bits of information per second, Drake decided to lay out his information in a grid.
This grid would contain 1,679 bits. Since 1,679 is the product of two prime numbers – 23 and 73 – Drake hoped this would show an intelligence had designed the signal.
He then chose to broadcast his image using binary, with black squares being 1 and colored squares being 0.
If aliens laid the code out on a grid, they’d eventually get images representing the numbers 1 to 10, the most-common chemical elements, a DNA helix, a human body, and even dots representing then then-9 planets, with the third dot raised to indicate our homeworld.
At the bottom, a crude picture of the Arecibo telescope and its wavelength would show any would-be aliens how to reply.
Although intended as a one-off, Drake’s message was so celebrated that it birthed METI – the scientific field devoted to Messaging ExtraTerrestrial Intelligence.
But it may have also done something else.
Depending on who you talk to, the Arecibo Message may soon become either the thing that inspired humanity’s greatest breakthrough… or alternatively doomed us all.
To understand why, we need to quickly talk about information leakage.
For nearly a century now, our planet has been leaking information out into space.
Radar pings, old episodes of I Love Lucy; all of it has been wafting away from Earth like an electronic fart, silently dispersing into the universe at the speed of light.
As of 2021, this shell of escaping information is thought to have reached 29 exoplanets that could potentially support life.
But, in the same way that a real fart slowly becomes harder to smell over regular odors, most of this information leakage is nearly impossible to detect among the universe’s background noise.
There could be aliens on those 29 planets listening out with our level of tech, who are completely unaware of the Leave it to Beaver broadcasts hissing through their atmosphere. Likewise, we could be missing their old transmissions of Celebrity Xenomorph Swap.
For most astronomers who believe we’re not alone, the challenge is to get better at listening for these signals. Hence SETI – the Search for ExtraTerrestrial Intelligence. Hence plans to utilize powerful telescopes like FAST in China to try to glimpse this leakage.
The METI community, by contrast, says Hell with this.
Rather than wait for ET to notice our leakage, they say we should be blasting high-powered broadcasts at habitable exoplanets. Broadcasts so strong, there’s no way anyone listening could miss them.
METI optimists hope this will encourage ET to call back. At their most optimistic, they hope this return call might contain something of value.
METI pessimists, by contrast, worry ET will instead come visit at the head of a fleet of interstellar warships.
If you’ve watched our Fermi Paradox video, you’ll recognize this outcome as the superpredator theory of the cosmos. The idea that broadcasting our location will result in immediate conquest.
For this reason, there are a great many serious scientists who are seriously scared about METI. Who are calling for the creation of international treaties to govern sending signals into space, and prison sentences for any individual who breaks these treaties.
The trouble is, it might already be too late.
In the years since Frank Drake sent out his Arecibo Message from the sweltering rainforests of Puerto Rico, all sorts of amateurs and crackpots have tried their hands at signalling aliens.
At the whimsical end of the scale, that includes stuff like Russian astronomer Aleksandr Zaitsev broadcasting Beethoven to the star 37 Geminorum in 2001.
At the utterly embarrassing end, it includes the time early social media casualty Bebo fired 500 user photos at the exoplanet Gliese 581 c – likely the closest humankind has ever come to an interplanetary declaration of war.
For head of the nonprofit METI International, Dr Douglas Vakoch, all this demonstrates that trying to stay quiet now is a fool’s game.
If advanced civilizations are out there, Vakoch thinks they’re already aware of our existence. The fact they haven’t already super-killed us suggests we’re not seen as a threat.
In that case, we might as well try and establish contact in the hope it’ll do humanity some good.
Yet even if you agree with Vakoch that the threat from Trisolaris is overblown, there are still a huge number of issues facing METI.
The greatest of these may be space itself.
Space is big. Really big. To steal a line from the Hitchhiker’s Guide to the Galaxy, “you may think it’s a long way down the road to the chemist, but that’s just peanuts to space.”
Since all communication is limited by the speed of light, this mind-boggling bigness seriously hampers METI efforts.
The message Frank Drake sent to the M13 cluster in 1974?
That won’t arrive until 25,974 AD. Even if it is picked up by someone, it’ll then take equally long for any reply to return.
The obvious answer is to only target star systems that are within a certain distance of Earth – say up to 20 light years – and have known, habitable exoplanets.
But since we can’t currently tell the difference between planets that are “habitable”, “inhabited”, and “inhabited, but only by stupid fish creatures,” even this becomes a crap shoot, with hundreds upon hundreds of stars to choose from.
With unlimited telescope time, you could easily broadcast to each in turn. But it’s here we hit METI’s second biggest problem: practicality.
People in charge of radio telescopes tend to like assigning timeslots to projects that have a reasonable chance of succeeding.
It’s probably telling that, in the six years since METI International was founded, it has only been given enough telescope time to broadcast two messages.
Which brings us to our final problem, which may be the most-interesting of all.
How do you design a message that can be understood by non-human intelligences?
Pioneering as Frank Drake’s attempt was, it’s not widely-considered to be suitable for use today.
Instead, recent serious METI broadcasts have gone to great lengths to talk in what may be the only universal language: maths.
Sent in 2017, the Sónar Calling message opens with second-long pulses arranged in such a way as to suggest basic mathematics.
Starting with 1+1 = 2, it slowly builds up to more complex concepts, including geometry and trigonometry.
The hope is that aliens will recognize what the initial pulses mean, and be encouraged to do the arithmetic to decode the later parts.
There’s even some pulses that simply count off seconds, hopefully to introduce the listener to our human concept of time.
Since the ideas in the Sónar Calling message are so basic, it’s hoped any civilization that hears it might reply back with something similarly mathematical. Something we could point to, and say “look! This is evidence of extraterrestrial intelligence!”
Yet while such a message would represent perhaps the most-profound discovery in human history, it would still leave us with a problem.
Where would we go from there?
Imagine, for a second, that Sónar Calling is detected by an unknown civilization at its target, Luyten’s star, 12 light years away.
Now imagine they reply likewise, with a series of pulses that reaches us 25 years after our initial broadcast.
Well, who gets to reply to that? How do we decide who should speak for humanity? What kind of message might our representatives send, and how do we know it won’t be mistranslated as “we are scary and you should fear us?”
And even if our communication goes smoothly, how do we deal with a ongoing conversation that will take place not over decades but centuries? One in which a single misstep could result in our annihilation?
Sadly, these are questions no-one has the answers to. But make no mistake, they are vital questions.
Every minute of every day, we’re leaking more and more information out into the galaxy. At the same time, METI researchers are hoping to target ever-more stars with powerful transmissions.
And each message they send out increases the likelihood that someone – or something – might hear it.
It may seem like fringe science, but it’s clear that METI could yet to turn out to be the single most-important undertaking in human history.
Whether it’s one that ends in our salvation, or our destruction, remains to be seen.
METI official website: http://meti.org/mission
The Arecibo Message: https://www.seti.org/seti-institute/project/details/arecibo-message
BBC, Will ET understand our messages?: https://www.bbc.com/future/article/20141112-will-et-understand-our-messages
New Scientist, trying to talk to aliens on another world: https://www.newscientist.com/article/2153461-we-just-sent-a-message-to-try-to-talk-to-aliens-on-another-world/
Wired, METI’s first message: https://www.wired.com/story/metis-first-message-is-a-music-lesson-for-aliens/
Washington Post, is contacting aliens just a really, really bad idea? (Cached): https://webcache.googleusercontent.com/search?q=cache:f3R0V4BHdD8J:https://www.washingtonpost.com/outlook/ufo-report-aliens-seti/2021/06/09/1402f6a8-c899-11eb-81b1-34796c7393af_story.html+&cd=10&hl=en&ct=clnk&gl=cz
BBC, should we be messaging aliens? https://www.sciencefocus.com/space/should-we-be-signalling-our-existence-to-alien-life/