Sara Rigby: Hello and welcome to the Science Focus Podcast. I'm Sara Rigby, online assistant at BBC Science Focus magazine.


In this week's episode, I'm talking to Dr Douglas Vakoch, president of Messaging Extraterrestrial Intelligence, or METI. We're going to talk about whether we should be broadcasting messages into space to signal our existence to intelligent alien species. So I think people might be more familiar with SETI, the search for extraterrestrial intelligence. So what exactly is METI and what's its purpose?

Dr Douglas Vakoch: Well, METI reverses the process of SETI. So SETI, searching for extraterrestrial intelligence, listens for radio or laser signals from space. At METI, we flip it around and instead of listening, we transmit powerful, intentional messages to nearby stars in the hope of eliciting a response.

SR: So why do you want to send out a signal? And how would that help us find alien life?

DV: Well, my big concern is that there are, in fact, a lot of other civilisations out there, but they're doing exactly what we are. They have these robust SETI programmes and everyone is listening, but no one is saying hello. And so this is our effort to join the galactic conversation. You know, we do hope that there are civilisations that are transmitting.

So we believe we should also be doing SETI, but in the same way that SETI has evolved over the past decades, this is a new strategy. So in the earliest days of SETI, astronomers did only radio SETI. They listened for radio signals. It's what they could imagine another civilisation transmitting.

But even in those early days, one of the pioneers of developing lasers, Charles Townes, had suggested that the aliens might be transmitting laser signals. All of his colleagues, though, said what? That's ridiculous, Charlie. No aliens would be able to do that. But then, as the decades progressed, by the time we got into the 1990s - so that first radio SETI search was 1960.

By the time we got into the 1990s, we realised, wait a second, we can do this now. So I think that it's the same sort of thing that we need to continually examine our presuppositions. We keep on doing radio SETI. We keep on doing optical SETI. And now we're saying we should add a third approach, which is transmitting messages.

More like this

SR: So have there been any messages of this sort sent before?

DV: Yeah, there have been sporadic messages sent out. The most famous message was transmitted was from the world's largest radio telescope at the time at Arecibo, Puerto Rico. And it was really kind of an afterthought to a rededication of the telescope after it had a major upgrade in 1974, created in the early 60s.

And so to demonstrate to extraterrestrials and actually to demonstrate to ourselves here on Earth that we have the ability, a brief three-minute message was sent out. That was really pretty ambitious in its scope. It was transmitted at two slightly different frequencies using the same transmitter that's used to study asteroids that are flying by. Send a radio signal, they bounce back. You can tell how far away they are, what their trajectory is.

But you can use the same instrument to send a message not now to a nearby asteroid, but to a nearby star or in the case of that transmission, to a much more distant target. But the message itself was the numbers from one to 10 in the binary format, then a description of chemical elements important to life on Earth in terms of their atomic numbers and then a description of our DNA, what we look like, how tall we are, how many of us there are on Earth, what our Solar System is like, what the telescope is like.

So it was pretty ambitious to cram a lot of information in three minutes. At METI, we take a bit different approach. And instead of trying to send them everything, send something that will be succinct and send them something that will be intelligible. So, my concern of sending everything is that maybe nothing will be understandable. So instead, we take the opposite strategy and send, instead of an encyclopaedia, a primer that is really targeted to alien scientists.

SR: So the Arecibo a signal, you said it was just a three minute-long signal. Do you think it's likely to be heard? That's quite a short burst of information.

DV: It's quite a short burst. And, you know, it doesn't follow the protocols that SETI scientists use here on Earth. So SETI scientists, you hear something. Once there was this famous signal in the 1970s called the Wow! signal. 'Wow!' because the next day the telescope operator looked at the printout and there was an off-the-charts strong signal.

So he wrote 'Wow!' in the margins, but we've never seen it again. So what do you do with that? I mean, was it a satellite flying by? Was it the emission from a car popping or was it really an alien signal?

So when we sent our first message as an organisation in 2017, we sent it three times over and over. So instead of sending it just once, three times. And then we came back 24 hours later. And then another 48 hours later, because that's what we said scientists want to do. We want to be able to go back and contact other astronomers and say, hey, I've got a live one here. I want you to follow up on it. Would you, and see if you see it, too?

Because the last thing we want is for this to be some kind of a hoax that's perpetuated by some grad students at MIT, or a glitch in our own system. So we want an independent confirmation. And so you've got to build in the time. So you're right on target. A one-off transmission is not enough.

You know, the other huge problem of the Arecibo message is if it is detected by the target recipients and they send a reply, we're not going to get that reply for fifty thousand years. Because it was sent, you know, it was, as I said, an afterthought to this commemoration ceremony. So the question was: what's pretty much overhead?

Because the Arecibo telescope is built into the surface of the Earth. And you can only point about 10 degrees of either side of straight up. And there's a prominent globular cluster of stars called M13 that was in target at the appropriate time. But it's 25,000 light-years away. So certainly we can do better than that.

When we transmitted, we transmitted to a star 12 light-years away. Luyten's star, which from the transmitter we use in northern Norway, it was the closest star that we could target that was known to have an exoplanet orbiting within its habitable zone. So maybe there's life there. And maybe looking at reply back in about a quarter century.

SR: So in general, do you want to be sending the message to a single target like that? Or would you want to be broadcasting widely?

DV: Broadcasting widely is the ideal because, you know, if you think about it, the only way that transmission to Luyten's star works is if the entire galaxy is populated and, you know, someone's out there and every star listening. And all we have to do is ping them and they'll reply back. I hope that's true, but I'm not going to hold my breath on that.

And so I think the strategy is to start with the nearest stars and then move outward. And the bulk of the nearest stars are tiny stars called red dwarfs. So they're much dimmer than our star. And in the earliest days of SETI, they were really kind of written off as target stars, because one of the consequences of being so small and so dim is that in order for a planet orbiting to get enough light and warmth to have liquid water, it would have to be really pretty close to that dim star.

The problem with that is there's a good chance it might be tidally locked. So the same, just like our Moon always has the same side facing Earth. So, too, with a tidally-locked planet. The good news is that in the decades since SETI first started, we've become much more optimistic that even on a tidally-locked planet, there could be enough heat distribution in the oceans and the atmosphere so that it wouldn't be just scorched on one side and frozen on the other.

And, you know, too, the more we learn about extremophiles - life that can live in the extremes of life here on Earth - and what I say, extremes, I mean, as extreme as the frozen tundra of the Arctic or acid hot springs or even the core nuclear reactors - the more optimistic we are that when we think about life existing in the habitable zone around other stars, maybe we've gone a bit too conservative.

And so it seems like once life takes hold, it can proliferate and thrive in a variety of environments. So we're looking at environments as close to Earth as possible just because the greatest challenge of METI is the timescale of sending a message and getting a reply back.

SR: Yeah, absolutely. And so is the goal to send a specific message? Are you trying to get any particular information across, or is it just to broadcast that we're here?

DV: We want to get a lot of different messages across. One of the real challenges that we have and you know, again, I think you see it in how fixated we became on only radio, the first 30 or so years of SETI. Once you have something that works well, it's easy to get fixated on that. And so it's easy to send elaborations of the Arecibo message. Other groups have done it as well.

You know, one of the things that you'll see in the Arecibo message are a lot of pictures. There's a picture of a human being. A diagram of the Solar System. A diagram of the double helix of the DNA molecule. Well, what happens if the alien is blind? So when we sent our message to Luyten's star, we designed it specifically for a blind alien.

So we wanted to push the boundaries a little bit. And so the way we did it is, you know, we can't count on the aliens having vision. One of the standard arguments for vision is that, well, look, it we evolve 40 times independently here on Earth. So we know it's really useful.

Yes, if you have an atmosphere that lets sunlight through. But if you don't, if you've got a murky atmosphere, it's not very useful. Maybe that's what the alien planet's like.

So we designed our message so that it conveys the most essential information that a physicist on another world would need to know to understand the only thing that we have that we can give them directly. And that's the radio signal itself. So we illustrate time by sending pulses of different durations.

We illustrate notions of frequency by sending messages of different frequency and then talking about that in basic mathematical terms. Now, does that mean radio waves should be the end all and be all of all future messages? Absolutely not. So we're developing a variety of messages. The next round of messages that we're just developing will capture something about how we communicate with one another for a project called Hello, Universe.

So we're building on this use of radio waves to communicate. We use that to communicate with the aliens. But we also use waves to communicate with one another at a different frequency, sound waves. So, using the same fundamental maths, we can talk about radio waves and sound waves, and now how we use that to communicate with one another.

But, of course, then the question is how much of a greeting Hello, Universe is going to be intelligible to an alien? Probably they're not going to understand the words. And so we always think of using something like the foundation for the Arecibo message, some basic maths, basic science. You know, if you don't know something that's as fundamental as two plus two equals four, you're going to be a pretty bad engineer, whether it's around Luyten's star or around our Sun.

So we start out with those basics. But we also took a step back.

You know, when we founded METI as an organisation, our goal was always to step back and re-examine our assumptions. So we've always said, well, the aliens won't speak English or French. And they won't, in that form.

But does that mean we have to write off natural language?

Maybe not. In 2018, we held a workshop as part of the International Space Development Conference. And one of the participants was Noam Chomsky, one of the founding fathers of linguistics. And for years, Chomsky had said, you know, if the Martians ever come to Earth and they hear us talking, they'll think these human languages are all just minor dialects because the underlying structure is the same.

But he'd never really been pushed to answer the question, well, would the alien languages have any underlying structure? And as he thought about it more, he said "I think they really would."

So there's one basic idea in linguistics called merge, where you take smaller components of a sentence and combine them, like a noun like 'aliens' and a verb like 'transmit'. So 'the aliens transmit'. Well, that's actually very similar to addition. One plus one equals two. So, combining things together.

So, you know, I don't expect they're going to have the exact words 'aliens' or 'transmit', but something like nouns and verbs, probably so. And so now we're starting to expand the notions of the messages we can send so that it could capture something about the complexity of our natural languages.

SR: So, these rules that are common across all languages, is that just spoken languages or did it also apply to things like sign language?

DV: It applies across languages. And, you know, it takes on different forms, of course, in different means of expression, whether it's a sign language. But again, that's an excellent example of how we need to go beyond just the communication that privileges one sensory modality, because it could be that the aliens don't have vision.

That's privileged. They don't have hearing this privilege. If you look at how much of our brain goes to processing different sensory modalities, a big chunk of our brain goes to processing vision and hearing. Not so much for touch or smell, but you can imagine an alien that's not only is it a cloudy planet with a really murky atmosphere, you can't see through it, but maybe it's already turbulent, very noisy.

So you can't communicate in that way either. And there is so much of our way of even conceptualising the nature of the world that's reliant on how we - I was going to say 'how we see it'. Even the words we used show how we privilege certain central modalities.

One of the things about both vision and hearing is that they suggest a very specific notion of even time and space, because you've got something in front of you and it's either here now or it's not.

And we can pinpoint objects very clearly in time and in space with both vision and hearing, but with a sense of smell, not so much. I mean, you get you go into a crowded lift. You smell a really strong perfume. Is it someone who's in there right now or did they just get off on the floor below? And so even different sensory modalities may have a different sense of time and space.

And, you know, I think that's one of the big payoffs that we're searching for, which is having to look at what we take for granted as the natural way of encountering the Universe and realising that intelligent beings on another planet with a different path of evolution may encounter the world in radically different ways.

SR: Some people have criticised the concept of METI, saying it could be risky to send out a message to aliens that we know absolutely nothing about. And what do you think about that? Do you think it's risky?

DV: You know, I think the point that people miss when they when they think it's risky is that the aliens we're worried about already know we're here.

So if we project our own level of radio technology just two, 300 years, we'll have the ability to detect the BBC as it's streaming out at the speed of light, out to a distance of about 500 light-years. Now, we don't currently have the ability to detect the twin of Earth giving off our level of natural radiation or leakage radiation, TV and radio. But that's OK. We also don't have warp drive. We don't have a way of getting to another star. So we're not a threat.

But just a tiny bit more advanced than we are, and they already know we're here. So, you know, there are a lot of things we have to worry about in this world. Nuclear war, global warming. I mean, it would be nice to take one existential threat off the list of worry. So I wish I could tell you that we would be safer if we didn't send out intentional messages in good conscience. I can't, though.

Because if there's anyone out there then they know we're here and, you know, even before the radio signals, they've had 2 billion years to know that there's complex life on our planet by changes in our atmosphere. That's a kind of technology that we're going to have. We're going to be able to detect the atmospheres that are indicative of life in 20 years as we continue our missions, space-based observatories.

So it's not going to be a surprise to the aliens. I think the bigger question then is, well, you know, if they already know we're here then what's the point?

So the purpose of METI, it's not to let the aliens know we're here for the first time. It's probably not going to be news to them.

Instead, it is examining a question that the Italian physicist Enrico Fermi asked back in 1950. If they're out there, where are they?

It's been called the Fermi Paradox and METI had a meeting in Paris last year. Every two years we have a meeting in Paris. And this one was focussed on the paradox specifically. One answer to that Fermi paradox that really motivates what we do at METI is called the zoo hypothesis.

So imagine, Sara, you and I go to the London Zoo and we're checking out a bunch of zebras. We're looking at them. We're just getting ready to move on. But all of a sudden, one of them turns directly toward us, looks us in the eye, starts pounding out a series of numbers with its hoof. I don't know about you, maybe you're going to go check out the wildebeest, but I'm going to take with the zebra and I am going to engage it.

And so it would establish a radically different relationship. We knew the zebras were there before. They just weren't especially interesting, or at least there was no indication that they were trying to reach out to us. So that's what we're trying to do with METI, is to reach out to another civilisation and say not only are we here, which you already know, but we want to make contact.

SR: So do you think that this is likely to work? Do you think it is likely that sending a message out will get a message back, or at least get us alerted to them by some alien species?

DV: I think there's a really good chance that it will work if we're patient. And I think that's the critical thing. Am I holding my breath that in 2042 we're going to get a reply back from Luyten's star that we pinged in 2017? No. I mean, I'm going to be listening. I don't think there's a good chance.

But if we repeat that experiment 100 times or a thousand times or a million times, then I think we have a realistic chance. So I think the greatest challenge, therefore, that we face is to reimagine ourselves as a species who is willing to take on this task of communicating with other long-lived civilisations.

And again, I assume they're going to be long-lived. You know, we've had radio technology for about a century. If that's the norm in our galaxy, a civilisation lasts for a hundred years and they either annihilate themselves or they turn inward and stop exploring.

Then we're not going to make contact. I mean, it's as if in the 13 billion year history of the galaxy, there are two fireflies that each flick on for a single moment in the course of the night. What are the chances it's going to be exactly the same time? Virtually zero. So the only way we make contact is if the other civilisations are much longer-lived than we are.

And so that's what we need to assume as we start searching and transmitting and listening. And then, of course, there's this sobering possibility that we transmit and we listen, century after century after millennium, all we hear is this profound cosmic silence. What then?

I would say that eventually it will dawn on us that simply by virtue of continuing to listen, by committing to this project without the guarantee that it will succeed, that still listening in thousands of years, we're going to realise that, in fact, even if we haven't found anyone out there, that we have become that long-lived civilisation we've been searching for all along.

So I think there is tremendous value in the search itself, in the commitment. I mean, if you look around the world today, a lot of our problems are because we're not willing to take a long-term perspective. So whether or not we find aliens, I think in the process of doing this work, we're going to find some increased intelligence and compassion.

SR: What gives you hope for the future of METI?

DV: Well, my hope is that everything we're learning about the Universe makes us think there could be life out there. You know, when SETI scientists started the first search in 1960, you could look up in the sky and you'd see all these stars, and say "I wonder if there's a planet around them?"

Now we go out, we look at those same stars and we say that virtually all of them are orbited by planets. Earlier on, I mentioned the variety of life forms that we know can populate extreme environments. So now we say, OK, if life takes hold somewhere, it's going to evolve.

So everything we're finding makes us more and more hopeful that there really could be life out there. And the Universe is a huge place. It's beyond my comprehension that there isn't someone out there somewhere in the Universe. But for those of us who want to make contact, the more interesting and more unknown question is, is there anyone close enough and motivated enough to make contact?

And so I think the big shift in METI as opposed to SETI is saying, look, if we want to become part of this galactic club - that's kind of the metaphor people sometimes say: we want to join the galactic club. It strikes me as so strange, though. No one ever seems to want to pay their dues or even submit an application.

And so that's what we're doing with METI. We're saying we want to join. And we realise we have to do our part, too. So here's our application. Are we what you're looking for?

SR: Brilliant. Thank you very much. Thank you for listening to this episode of the Science Focus Podcast. That was Dr Douglas Vakoch, president of METI. In the latest issue of BBC Science Focus magazine, we debunk the biggest myths in food and diets. We take a look at NASA's Artemis programme, Dr Michael Mosley explains how to manage seasonal affective disorder, and we dive into the weird world of sea slugs.

Listen to more episodes of the Science Focus Podcast:



Sara RigbyOnline staff writer, BBC Science Focus

Sara is the online staff writer at BBC Science Focus. She has an MPhys in mathematical physics and loves all things space, dinosaurs and dogs.