The Problem of Talking to an Alien

On November 16, 1974, researchers at the Arecibo radio telescope in Puerto Rico did something remarkable. They transmitted a message, via frequency-modulated radio waves,  toward the globular cluster Messier 13. Also known as M13, this cluster is some 25,000 light-years away from us. This was remarkable not because it was an earnest attempt to make a phone call to our galactic neighbours, but because it was a demonstration that we’d finally built a telephone capable of doing so. A technological feat heretofore unknown.

The attempt brought a rather sticky problem to the fore, however. What should we say? And how should we say it?

The message they sent has become known as the Arecibo Message, and it was composed after a good deal of deliberation by a team at Cornell University, in conjunction with Arecibo scientists. This team, headed by pioneering radio astronomer Frank Drake, designed a binary message encoding representations of concepts such as the atomic numbers of the elements that make up our DNA, an estimate of the number of nucleotide pairs in the human genome,  and even a graphic of our solar system with an indication of which planet the message originated on.

As mentioned, no one at the time expected any sort of response to the signal, since the great distances involved mean that the earliest we might receive a response is about 50,000 years from now. But it provided an opportunity to think about something that hadn’t really been covered to any great depth until then. 

How do you communicate with a non-human intelligence?

It seems painfully obvious that an extraterrestrial intelligence wouldn’t speak English (or any other human language), but the problem may actually go deeper than that. Let’s demonstrate.

Darmok and Jalad at Tanagra.

This, of course, is the famous line from Star Trek: The Next Generation (Season 5, Episode 2), wherein the larger-than-life Jean-Luc Picard faces off with an alien race who have trapped him on a desolate planet in a desperate attempt to open communication. His trusty universal translator is nearly useless because of a peculiarity of this alien language. Of course, as we’ll see, that peculiarity isn’t really so peculiar.

The problem Picard faced was that this alien species (the Tamarians) speaks only in metaphor; thus, a detailed knowledge of their cultural history is required to understand them. Picard is able to discern and understand discrete words, but has no frame of reference for their broader meaning. Eventually, he discovers this feature of their language and is slowly able to construct a mutual understanding by sharing some of our own cultural metaphors. His success comes too late for the Tamarian captain, but just in time to stave off a battle between the Enterprise and the Tamarian vessel.

That episode highlights something useful to this discussion. Namely, that shared cultural understanding is actually a core component of human language, too. Our vocabulary and language structure are dependent on an inherent agreement, or social contract, if you will, that certain vocal sounds represent certain ideas. But that agreement depends, at least in part, on a shared frame of reference. For example, the phrases Achilles’ heel, Pandora’s Box, David and Goliath, Catch-22, Big Brother, and Frankenstein’s monster all require both the speaker and the listener to possess at least a familiarity with the cultural reference embedded in the phrase. A perfect translation of the words themselves is not enough. Without the story of Achilles, his troublesome heel is just a strangely specific anatomical reference.

Of course, most human language isn’t quite so dependent on metaphor. I don’t need to know anything about your cultural history to understand what you mean when you point at a rock and call it a rock. But even this apparently simple exchange rests on a remarkable amount of common ground. We both recognize discrete physical objects, possess similar senses with which to perceive them, and have sufficiently similar brains to divide the world into broadly similar conceptual categories. More importantly, we understand that the sound rock can stand for the object being indicated. None of this seems particularly remarkable to us because virtually every human being with whom we communicate possesses essentially the same biological equipment and inhabits essentially the same perceptual world.

When you stop to consider everything that has to go right, it is rather remarkable that one mind can communicate an idea to another mind at all. 

An extraterrestrial intelligence offers no guarantee of any of those things. It may not perceive the world through anything resembling our senses, divide its surroundings into the same categories, or even possess concepts corresponding neatly to object, individual, place, or time. Before we can worry about whether it understands the sounds we make with our mouths, there is a more fundamental problem: whether the ideas those sounds represent are mutually intelligible in the first place.

Frank Drake et al. tried to circumvent that barrier in the Arecibo Message by composing it in what’s often described as the universal language of mathematics. But Drake’s solution doesn’t necessarily get all the way around the problem.

Take the example of prime numbers, often proposed as a potential basis for communication because recognizing them requires no knowledge of human culture. It only requires that both parties recognize the same underlying mathematical relationships. If an extraterrestrial civilization is capable of radio astronomy (which would be necessary for it to receive our message in the first place), it presumably has encountered quantities, regularities, electromagnetic radiation, chemical elements, and physical relationships. Hydrogen behaves the same way on Earth as it does around another star. Two objects plus two objects make four objects regardless of what symbols anyone uses to represent “2” and “4.” Prime numbers remain prime regardless of whether anyone calls them primes.

The Arecibo Message consisted of 1,679 binary digits, a number deliberately chosen because it’s the product of two primes: 23 and 73. The intended recipient would have to recognize this and infer that the sequence could be arranged into a 23-by-73 grid, at which point the message begins to resemble a series of pictograms.

You don’t need to point at a hydrogen atom and say “hydrogen” if both civilizations can independently identify its physical properties. In principle, nature itself becomes the dictionary. But this may presuppose that such an extraterrestrial intelligence will recognize that the signal contains discrete units.

It must infer that two signal states represent something analogous to binary information. It must count those units. It must recognize prime factorization as significant.

It must infer that the sequence should be rearranged spatially.

It must choose a two-dimensional rectangle.

It must determine which dimension is horizontal and which is vertical, and in which direction the sequence runs.

And after all that, it must interpret the resulting pattern as a pictorial representation.

The mathematics itself may indeed be universal, but the method we’ve chosen to represent it is not. And with the Arecibo Message, Drake eliminated the requirement for shared human culture, but he couldn’t eliminate the requirement for some degree of shared cognition.

This is all very interesting, for sure, but perhaps we don’t need to speculate about whether an independently evolved intelligence perceives and categorizes the same world differently. We have such independently evolved intelligences here on Earth already.

Consider dolphins, arguably among the most intelligent species on the planet, yet after decades of research we still struggle to determine whether their sophisticated communication systems constitute anything analogous to human language, let alone whether meaningful two-way communication between our species is possible. Dolphins inhabit a sensory world profoundly different from our own. They utilize whistles, other vocalizations, body movements, and physical contact as signals, while echolocation gives sound a role in their perception of the world that humans can only approximate. 

And yet dolphins should present us with a comparatively easy version of the problem. We share a planet with them. We share the same chemistry and physics, a distant evolutionary ancestry, and the basic biological architecture of mammalian brains. We can observe them directly, record their vocalizations, watch how other dolphins respond, and repeat our experiments thousands of times. We don’t have to wait 50,000 years for another transmission.

Despite all of those advantages, we still cannot listen to a sequence of dolphin vocalizations and confidently tell you what it means.

That should give us some pause when imagining communication with an intelligence that evolved beneath another sun.

The Wild Dolphin Project has been studying wild Atlantic spotted dolphins in the Bahamas since 1985. They’ve accumulated decades of recordings of dolphin vocalizations that can be associated with individual dolphins, their behaviour, and specific social contexts. That research has produced enough data to train a machine-learning model developed by Google, known as DolphinGemma.

Conceptually, it does something analogous to a language model, or LLM: given a sequence of dolphin sounds, it learns recurring patterns and predicts likely subsequent sounds. It can also generate dolphin-like sequences. Researchers hope those capabilities will reveal structures, clusters, and recurring sequences in dolphin vocalizations that would be extremely difficult for humans to find manually. But predicting structure and organization doesn’t necessarily translate to deciphering meaning.

Just because sound A frequently comes before sounds B and C doesn’t automatically imply that the sequence means, “There’s a shark behind you.” We may recognize the pattern without understanding what, if anything, the pattern represents.

So, what does the above say about the possibility of communicating with an alien civilization far, far away? While we may have the technological capability of sending messages back and forth, however slowly, we have some serious problems to overcome before we can achieve understanding on either side of the phone call.

Though dolphins inhabit a sensory environment drastically different from ours, we share a planet, an evolutionary history, chemistry, and biology with them. And yet, even after decades of direct observation, we still struggle to move beyond recognizing structure and organization and into actual understanding. If establishing meaningful communication with another intelligent species on our own planet remains this difficult, what happens when we encounter life that evolved in an environment so drastically different from our own that the very concept of communication may itself be alien?

So long, and thanks for all the fish!