Extraterrestrial Languages

by Daniel Oberhaus

If we send a message into space, will extraterrestrial beings receive it? Will they understand?

The endlessly fascinating question of whether we are alone in the universe has always been accompanied by another, more complicated one: if there is extraterrestrial life, how would we communicate with it? In this book, Daniel Oberhaus leads readers on a quest for extraterrestrial communication. Exploring Earthlings' various attempts to reach out to non-Earthlings over the centuries, he poses some not entirely answerable questions: If we send a message into space, will extraterrestrial beings receive it? Will they understand? What languages will they (and we) speak? Is there not only a universal grammar (as Noam Chomsky has posited), but also a grammar of the universe?

Oberhaus describes, among other things, a late-nineteenth-century idea to communicate with Martians via Morse code and mirrors; the emergence in the twentieth century of SETI (the search for extraterrestrial intelligence), CETI (communication with extraterrestrial intelligence), and finally METI (messaging extraterrestrial intelligence); the one-way space voyage of Ella, an artificial intelligence agent that can play cards, tell fortunes, and recite poetry; and the launching of a theremin concert for aliens. He considers media used in attempts at extraterrestrial communication, from microwave systems to plaques on spacecrafts to formal logic, and discusses attempts to formulate a language for our message, including the Astraglossa and two generations of Lincos (lingua cosmica).

The chosen medium for interstellar communication reveals much about the technological sophistication of the civilization that sends it, Oberhaus observes, but even more interesting is the information embedded in the message itself. In Extraterrestrial Languages, he considers how philosophy, linguistics, mathematics, science, and art have informed the design or limited the effectiveness of our interstellar messaging.

Genres: Science, Nonfiction, Linguistics, Space, Language, Philosophy, Astronomy

264 pages, Hardcover

Published October 22, 2019

About the author

Daniel Oberhaus is a science and technology communicator based in New York City.

He is represented by Robert Guinsler at Sterling Lord Literistic and the author of two books for MIT Press.

His most recent book, The Silicon Shrink (2025), is about the promise and peril of AI in psychiatry. His first book, Extraterrestrial Languages (2019), is about the art, science, and philosophy of interstellar communication.

Daniel is the CEO and founder of HAUS, a strategic communications agency for deep tech startups. Previously, he was a staff writer at WIRED Magazine covering space exploration and the future of energy.

Reviews

[Brian Clegg · Rating 3 out of 5]

Despite the title, this book isn't about the languages that aliens use, but rather how should we format messages that are intended for non-human recipients? Every now and then, we send something off into space, whether it's the inscribed plaques on the Pioneer probes or messages beamed from radio telescopes. Whether we should do this or not is a contentious issue - Daniel Oberhaus briefly examines the arguments for and against - but the meat of the book is trying to answer the question 'If we do want to communicate to aliens, how could we make our message comprehensible?'

Oberhaus opens the book with a fascinating story I hadn't heard of the astronomer Frank Drake sending a message (by post) in 1961 to 'nine of the smartest individuals in the United States' as a hypothetical message from outer space, consisting of 551 zeroes and ones. The recipients were supposed to spot that this is a multiple of prime numbers, array the zeroes and ones by these numbers and interpret the visual message then presented. None understood it (though one did spot it was a visual array in this format and replied in kind). This so strongly underlines how difficult it is to send a message to someone who has no clue about the format. If humans couldn't interpret a message from other humans, how much harder would it be for a truly alien species?

In the book, Oberhaus takes us through the mechanisms used in the various attempts as well as some theoretical ways of communicating such as artificial languages that have never been used. It is genuinely interesting, but I found it too technical - there were pages at a time that were very hard to get your head around if you aren't involved in the field.

Apart from this occasional impenetrability, as someone involved in improving the quality of university essays, I was a little worried about Oberhaus's assertion that 'Gauss was correct in his estimation of the importance of extraterrestrial contact [as a greater discovery than America]' being made without any evidence to back it up. Bearing in mind we are almost certainly talking about one way communication, I'm not sure this is at all obvious.

Overall, I think the biggest omission is that Oberhaus is not critical enough of the various attempts, which seem intensely naive in their assumption that aliens would be able to (or could be bothered to) interpret something that the chances are no one on Earth could decipher. This is perhaps best underlined in a section on using the arts to communicate. While Oberhaus does end up mostly closing down this approach at one point he says 'One possible solution is to use solely abstract art, which may be considered universally intelligible given its rejection of "cultural, historical or political contexts". This seems totally back to front - abstract art entirely fails to communicate anything concrete with any certainty, being entirely dependent on interpretation.

So, a fascinating topic if, perhaps, talking about a pointless exercise, but could have been addressed more critically and should have been written in less of an academic style if it were to be made approachable by the general reader.

[Pavle · Rating 2 out of 5]

Oberhaus piše o porukama koje smo poslali u svemir i načinima kako smo pokušail da ih učinimo razumljivim za potencijalne vanzemaljske primaoce. Piše o sadržaju poruka, o načinu kodiranja, o načinu slanja. Ta tema zvuči poprilično zabavno, ali knjiga je, nažalost, dosadnjikava.

Popularna nauka može da ode malo previše u stranu popularnog, ili malo previše u stranu nauke. Ova knjiga, pak, ne ode dovoljno ni u jednom smeru. Oberhaus koristi velike reči i naučne termine, koje prethodno ne definiše, pa je onda to o čemu piše istovremeno i suvoparno i nedovoljno definisano. Neke od stvari o kojima piše su bliske mom obrazovanju, i tu dobijam jak utisak da on njih ne kapira - koristi on sve ključne reči, ali rečenice često ne idu nigde.

Nije sve baš tako crno - ima simpatičnih priča vezanih za slanje poruka, neke od tih poruka su vrlo interesantne, samo ostaje malo greota što je uprkos vrlo zabavnoj temi, knjiga poprilično mlaka.

[Sara · Rating 3 out of 5]

An interesting if not exactly enjoyable read. It’s more about the problem of communication on our end rather than speculation about alien languages. I found myself skimming in some of the chapters as the writing was dry, and it was taking an awfully long time to state things that were either a) clear after a few sentences, or b) were highly technical and inaccessible (to me). I take full blame for the latter. The subject is fascinating, and as an overview of the problem, it’s well worth reading.

[Arno Mosikyan · Rating 5 out of 5]

307: In 1971, dozens of astronomers and astrophysicists convened in a conference room at the Byurakan Astrophysical Observatory in Armenia for the first joint American and Soviet conference on communicating with extraterrestrial intelligence.
311: In this sense, the Byurakan conference was as much about extraterrestrials as it was about easing tensions between two global superpowers.
338: Among the various proposals for interstellar messages raised at Byurakan, one especially stands out. Marvin Minsky, one of the progenitors of the field of artificial intelligence, suggested it would be best to send a cat.
549: Shortly after the conclusion of Project Ozma, the National Academy of Sciences requested that Drake meet with other scientists to determine the future of SETI—or, for that matter, whether SETI should have a future at all. The three-day meeting was scheduled to begin November 1, 1961, at Green Bank, and a few days ahead of the conference Drake pieced together an agenda that would address “all elements needed to predict the difficulty of detecting extraterrestrial life.” The list he came up with included the average rate of star formation, the percentage of stars hosting planets, the average number of habitable planets per star, the percentage of planets where life emerges, the percentage of planets with life where intelligence evolves, the percentage of intelligent societies capable of interstellar communication, and the number of years a civilization is sending out detectable signals (Drake and Sobel 1992). Drake realized that multiplying the value of these items together resulted in a rough estimate of the number of communicating extraterrestrial civilizations in the Milky Way—and with this realization, the famous Drake equation was born.
586: As Chomsky and others have argued elsewhere, human language can be used for communication, but this is apparently not its primary purpose. Natural languages are mostly used internally to order thoughts and only relatively infrequently to convey these thoughts to others.
588: Therefore Chomsky refers to natural languages as internal languages, or I-languages, which must be distinguished from language as the computational system consisting of a small set of discrete rules—the universal grammar—discussed in the previous chapter. There is a nearly endless variety of communication systems, ranging from manner of dress and avian plumage to body “language” and the chemical secretions of plants. Although natural languages can fulfill these communicative functions, they cannot be reduced to them.
604: By reducing language to mere communication, Lilly missed a crucial insight: communication systems only convey information, whereas language is also able to convey thought.
797: The significance of this division was not lost on Minsky. “I claim that most information that people have that is important is not facts, but processes,” Minsky said at the Byurakan conference.
815: Indeed, there is good reason to presume that most extraterrestrials in the universe are “postbiological” artificial intelligences (Bainbridge 2013; Dick 2006; Sandberg, Armstrong, and Cirkovic 2017).
1036: The conundrum was eloquently described by Albert Einstein (1922), who wondered “How is it possible that mathematics, a product of human thought that is independent of existence, fits so excellently the objects of physical reality?”
1192: It would be naïve, of course, to suggest that evolution is totally determined by the laws of physics given the significant and obvious role that chance plays in the trajectory of evolution. For example, research suggests that the probability of an asteroid impact resulting in global cooling, mass extinction, and the subsequent appearance of mammals was “quite low” 66 million years ago. It was sheer cosmic bad luck that the asteroid impacted the relatively small portion of the Earth’s surface that was rich in the hydrocarbons and sulfur that ultimately choked the Earth with stratospheric soot and sulfate aerosols. In this case, the site of the asteroid impact changed the history of life on Earth in a way that could never be predicted by deterministic evolutionary laws (Kaiho and Oshima 2017).
1350: On May 24, 1999, the first Cosmic Call message was broadcast from Evpatoria to a star in the Cygnus constellation approximately 70 light years from Earth. The message was transmitted at 100 bits per second (except for the public portion, which was transmitted at 2,000 bits per second) on the 5.01 GHz (6 cm) band. (This isn’t a “magic” frequency but was the frequency at which the radio telescope was equipped to broadcast.) The transmission used frequency-shift keying to modulate the radio signal, which shifted the transmission frequency by 24 kHz to encode the message as a ternary stream. The message itself was encoded in binary, such that 0 was represented at 5,010,000 kHz, 1 represented at 5,010,048 kHz, and a five-second pause between each of the messages was represented at 5,010,024 kHz.
1494: Sagan and Drake’s choice of the hydrogen atom was deliberate. As the most abundant element in the universe, the spectral line of neutral hydrogen was considered at the time to be the most promising frequency to search for an extraterrestrial message. By calling attention to this radio frequency, Sagan and Drake were effectively giving an extraterrestrial recipient Earth’s phone number. If they were to call on that frequency, someone would probably be listening. Yet a phone number doesn’t do much good if you don’t know the area code, and the same goes for interstellar communication. To this end, the Pioneer plaques include two maps to assist an extraterrestrial in locating Earth. One of the maps depicts the nine planets of our solar system (Pluto was still dignified with planetary status in 1972) and the Sun. An arrow drawn from the third planet and looping around the fifth depicts the Pioneer’s trajectory from Earth around Jupiter. The relative distance between the planets is labeled in binary. The second map consists of fifteen lines all emanating from a common origin. Fourteen of these lines consist of a long binary number that corresponds to a ten-digit number in decimal notation. These lines correspond to the distance of the Sun from fourteen different pulsars; the fifteenth line corresponds to the distance of the Sun from the center of the galaxy. Yet what is an extraterrestrial to make of the binary numbers? Once again, it appears that these numbers could represent either a time interval or a length.
1569: Despite their best intentions, the Voyager record and Pioneer plaques are each a sort of cosmic message in a bottle that is unlikely to ever wash up on alien shores. Even if the craft were intercepted, the deep anthropocentrism of each message makes it unlikely that their contents would be correctly deciphered.
1590: Since most astrophysical noise is smeared across a very wide band of frequencies, the conventional wisdom is that a broadcast on a single, narrow carrier frequency is more likely to stand out as intelligible signal to any extraterrestrials that may be listening (Shostak 1995). Modern SETI programs can scan millions of narrow channels (e.g., around 1 Hz) in real time and up to billions of channels offline. Monitoring narrowband channels reduces the background noise because the channel represents only a small portion of the broadband noise, while at the same time “cranking up the volume” of any signal intentionally broadcast on that frequency. There is good reason to suspect that any extraterrestrial radio astronomers would adopt similar narrowband search strategies.
1613: The range of frequencies spanning from 1.420 GHz and 1.720 GHz is known as “the water hole,” given that the combination of a hydrogen atom and a hydroxyl molecule produces water.
1618: Although 1,420 MHz was the chosen frequency for Project Ozma and many other SETI observations thereafter, it may not be as ideal for communication as was once presumed. Frequencies between 1 and 3 GHz (which includes the water hole) have since been shown to be particularly susceptible to interstellar electron clouds that cause a signal’s bandwidth to increase. In fact, the most detectable signal that uses the least amount of power was calculated to be at around 70 GHz (Drake and Sobel 1992), which is still within the universe’s “quiet zone,” but well outside Earth’s microwave window. This implies that our atmosphere may be blocking any incoming extraterrestrial signals on this optimal frequency, while also precluding optimized broadcasts.
1623: Even if we established a METI outpost on the moon for broadcasting and receiving, the detectability of our signal would now be further restrained by the assumption that our extraterrestrial targets have also overcome their atmospheric opacity. Fortunately, there are other reasonable magic frequencies that still allow for broadcasts from terra firma (for a thorough overview of the rationale behind many leading frequency candidates, see Blair and Zadnik 1993 and Townes 1957, 1983). A few notable examples include harmonics of the hydrogen line, at 2.840 GHz; the product of the hydrogen line and pi, justified on the grounds that the irrationality of pi means that this frequency couldn’t be produced naturally as a harmonic and would thus distinguish the signal as artificial (Zaitsev 2011); 8.67 GHz, which is the spin-flip transition of 3He+ ion, chosen because it has the next simplest transition after atomic hydrogen (Bania and Rood 1993); and 203.385 GHz, which corresponds “to the splitting of the ground state of the lightest atom—positronium—and [coincides] with the centroid of the relic background spectrum” (Kardashev 1979).
1668: The design of an interstellar radio message thus requires a cost-benefit analysis that considers the bandwidth of the signal, the target star system, the power of the transmitter, the selected frequency, and the data rate of the transmission, as well as some assumptions about the nature of the extraterrestrial receiving technology. Taken together, these set restrictions on the size of the message that is sent. Consider, for example, a situation in which the Arecibo telescope is used to transmit a message at 1,420 MHz to an extraterrestrial civilization 100 light years distant that has a comparable receiving telescope. Best practice in radio communication suggests that the bandwidth of a signal will be between 0.1 and 10 percent of the carrier frequency (Shostak 1995), so a broadcast at 1420 MHz would use a bandwidth of about 70 MHz. If the desired signal-to-noise ratio is 1—a remarkably clear signal—then the equation for the amount of information that can be transmitted over this channel returns 70 megabits per second, or about 750 gigabytes of information each day (Shannon 1948). The feasibility of this scenario depends on the ability to achieve a signal-to-noise ratio of 1, which is a function of the power density of the transmitter. In this case, achieving this signal-to-noise ratio would require a power density of 1 kilowatt per hertz, or 70 gigawatts spread across the entire 70 MHz band. This energy requirement is considerable: it represents approximately 0.5 percent of the total energy generation capacity of Earth, which is far beyond the reach of our most powerful radio telescopes (Shostak 2009).
1798: The importance of protecting WIPP, the first dedicated subterranean nuclear waste repository in the United States, from future human intrusion wasn’t lost on its architects. In 1985, the US Environmental Protection Agency issued a directive that highlighted the need for warning markers that would prevent inadvertent human intrusion for ten thousand years—the regulatory lifetime of the repository. Considering that the oldest written records on Earth only date back about five thousand years and the meaning of several ancient scripts has been lost to history, creating a message that would be intelligible for twice that time period was a daunting challenge. In accordance with the EPA’s directive, Sandia National Laboratories convened a working group of scientists, linguists, anthropologists, and artists who were tasked with designing warning messages that would be intelligible for ten millennia. A notable feature of the thirteen-member task force was the strong representation of SETI researchers, including Woodruff T. Sullivan, Frank Drake, and Jon Lomberg, the artist who designed the original iconography for the Voyager golden records.
2010: In 2015, over two dozen scientists, academics, and industry leaders affiliated with the University of California Berkeley’s SETI program, arguably the leading search effort in the world, signed a statement calling for a moratorium on interstellar broadcasts until “a worldwide scientific, political, and humanitarian discussion” occurred. These critics of METI raised four principle arguments against transmission, which can be characterized as “shouting in a jungle,” the pseudoscience argument, the profligate transmissions argument, and “Who speaks for Earth?”
2015: Shouting in a Jungle The “shouting in a jungle” critique is inherited from Ryle. It is based on the historical observation that contact between cultures with asymmetrical levels of technological development has frequently led to the extermination of the less technologically advanced culture.
2030: Radio and television broadcasts, for example, are common all over the planet, so this results in near-isotropic radiation into space. This creates a sort of sphere of radio noise around the Earth whose radius—currently about 80 light years—is equivalent to the amount of time these broadcasts have been occurring.
2085: Is METI Scientific? Another criticism of METI is that it is a form of “unauthorized diplomacy” rather than a hard science (Michaud 2005; Gertz 2016).
2086: This critique depends on how science is defined, however, which is a contentious topic among philosophers. One of the most widely accepted delineations between science and pseudoscience was advanced by the philosopher Karl Popper (1959), who defined a scientific hypothesis or theory as one that is falsifiable. As far as METI is concerned, the accusation that interstellar messaging constitutes a pseudoscience has more to do with the transmission of messages than their design. For example, METI practitioners could advance the hypothesis that an extraterrestrial exists in a given star system and send a message to test this hypothesis. However, the lack of a reply to the message does not confirm or refute the existence of an extraterrestrial intelligence in that solar system. Perhaps the message was missed by the extraterrestrial, or they simply decided not to respond. Of course, a similar claim to pseudoscience could be lodged against SETI. In both cases, there are never refutations of the hypothesis, only confir

[Leanne · Rating 4 out of 5]

Imagine finding out that intelligent life had been discovered in a galaxy far, far away. To learn that across the endless ocean of intergalactic space there exists a planet filled with new forms of life –and riches unimagined. If we can only find them…

It won’t be as easy. Even in the 17th century people knew that flying to the moon in a chariot pulled by wild geese wouldn’t bring them face-to-face with aliens.

Maybe you’re thinking we could detonate all the nuclear bombs in the world on the far side of the moon to get their attention?

Well, it might, but the aliens would have to be looking at just the right moment when the x-rays ripple past their telescopes.

Astronomers have long been searching the radio waves of the universe for a message in a bottle. But so far, nothing has washed up. Radio silence.

For such a fascinating and exciting subject, the writing was surprisingly flat. If he had been a physicist or a linguist, I could forgive the writing that is so completely lacking in wit or style. But he is a journalist by trade. The story itself has so much potential, and the review in the London Review of Books was written in such an engaging manner that when I got my copy of the book, which I bought immediately after being dazzled by the review, it was hard to plow through. It is not that he is overly technical—since he wisely puts all the technical discussion in several sections in the back. The chapter on art and symbols was really interesting! It was well done, not unlike the last chapter of McFarland’s book about designing signs that will last 100,000 years

The topic is so engaging and he does such a great job talking about both the history as well as passive versus active communication… it is a must-read. Too bad the writing wasn’t more polished.

[Eden Katz · Rating 5 out of 5]

amazing experience. i learned so much, from linguistics and sociology and anthropology to math and programming and astrophysics. the writing is a bit dense at times, but the author makes up for it with abundant examples and in-depth appendices. i now want to change my career path to study the possibilities of extraterrestrial languages full time.

[Tony Gualtieri · Rating 5 out of 5]

This is a tremendous philosophical rumination on how earthlings can communicate with other intelligent beings in the universe. It raises issues of linguistic structure, comprehensibilty, broadcasting limitations, and whether we should be sending messages at all. Along the way, there are anecdotes that enliven the text and details of how messages have been created.

[Stone · Rating 2 out of 5]

Small book. This book uses formal referencing system so it is very academic, however not very coherent to read. Sometimes it uses a lot of jargon (especially when it talks about radio and microwaves). Some of the inferences are really fascinating. Lots of fun facts are covered as well. It is a good book for reviewing different methods used in human SETI history, but author is a METI man.

Highlights:
“the same structures that make it possible to learn a human language make it impossible for us to learn a language that violates the principles of universal grammar. If a Martian landed from outer space and spoke a language that violated universal grammar, we should simply not be able to learn that language the way that we learn a human language.”
This revolution in brain imaging technologies led to an unambiguous conclusion: Our cognition is shaped by our bodily experiences. The very structure of our brain is optimized to allow our bodies to effectively engage with the world around us, which suggests that our embodied mind is the bridge between mathematics and the physical world.
(inference. brain structure. grammar capacity)

we would have to “approach the alien’s language slowly and laboriously—the way that scientists study physics, where it takes generation after generation of labour to gain new understanding and to make significant progress”
(long process)

They realized that the search for extraterrestrial intelligence shared many similarities to their own search for artificial intelligence, insofar as it was the “attempt to study intellectual mechanisms as independently as possible of the particular ways intellectual activity is carried out by humans”
(AI)

the methods of intelligence are determined by the nature of the problem at hand. For example, the ability to play games like chess and Go requires mastering processes like searching for solutions and breaking a situation down into constituent elements.
(AI)

Extrapolating from the objective mechanisms of intelligence and a universal principle of economy, Minsky (1985) argued that we will be able to converse with an extraterrestrial intelligence because they will think like us. If all intelligent creatures are faced with the same fundamental problems (i.e., restraints on space, time, and materials)
(inference. economy. restraints. similarity between us and ETI)

the methods of intelligence are determined by the nature of the problem at hand, Minsky reasoned that extraterrestrial intelligence will arrive at solutions similar to our own, namely symbolic systems for representing these problems and processes for manipulating those systems that can also be described symbolically.
(inference. problems to intelligence)

there are special ideas that “every evolving intelligence will eventually encounter” because they are simpler than other ideas that result in the same product. Two examples of these special ideas are numbers and arithmetic, which is why they may serve as a strong basis for an interstellar message.
(inference. numbers. arithmetic)

Thus, it would appear that the economy born of certain universal restraints—the laws of physics and the scarcity of resources—gives us good reason to suppose that extraterrestrial cognition will be sufficiently similar to our own to allow meaningful communication to take place.
(inference. prevalence. resource. laws of physics. cognition)

human language can be used for communication, but this is apparently not its primary purpose. Natural languages are mostly used internally to order thoughts and only relatively infrequently to convey these thoughts to others.
(language. communication)

Lilly defined communication as “the exchange of information between minds,” which involved a certain degree of abstraction insofar as “information does not exist as information until it is within the higher levels of abstraction of each of the minds and computed as such.
(abstraction. communication)

By reducing language to mere communication, Lilly missed a crucial insight: communication systems only convey information, whereas language is also able to convey thought.
(abstraction. communication)

while some dolphins are reported to have learned English—up to 50 words used in correct context—no human being has been reported to have learned dolphinese.”
(inference. If we cannot communicate with dolphin, how aliens?)

Given that nonhuman animals do not have what we would call language but nevertheless possess complex communication systems, exploring the boundaries between language and communication is particularly relevant to the task of designing a message that will be recognized by extraterrestrials as an intelligent signal.
(communication. language)

Given that any extant extraterrestrial civilizations are likely more advanced than our own, it is reasonable to presume that an extraterrestrial intelligence has developed its own AGI (Shklovskii and Sagan 1966). Indeed, there is good reason to presume that most extraterrestrials in the universe are “postbiological” artificial intelligences (Bainbridge 2013; Dick 2006; Sandberg, Armstrong, and Cirkovic 2017).
(inference. postbiological)

To the best of our knowledge, the laws of physics are the same throughout the universe, which suggests that the facts of science may serve as an adequate basis for mutual understanding between humans and an extraterrestrial intelligence.
(inference. universal language)

According to the Platonists, mathematics would exist regardless of whether there were any minds—human or otherwise—around to perceive it, because mathematics is literally a part of the universe and endows it with a rational structure. On this view, mathematics is something that is discovered, not invented.
(maths)

mathematics is effectively an exercise in manipulating inherently meaningless symbols according to fixed rules. DeVito acknowledges that mathematics “may be more reflective of our minds than we realize and may say more about human nature than it does about the real world”
(maths)

there is good reason to suspect that our preference for whole numbers is a result of the constraints of the human mind; an extraterrestrial with a stronger short-term memory might not prefer natural numbers over, say, irrational numbers
(inference.number)

Charles Cockell has argued, empirical evidence suggests that certain features of life are deterministically driven by physical laws. Extrapolating from this, it is reasonable to believe that “at all levels of its structural hierarchy, alien life is likely to look strangely similar to the life we know on Earth” Cockell’s argument is analogous to the case made by Minsky that extraterrestrials are likely to think like us because they are subject to the same basic physical constraints.
(deterministic)

RNA, the molecular interface between DNA and basic proteins, suggest that four nucleotides result in the greatest fitness. As for the types of base pairs, research using synthetic nucleotides to expand the number of base pairs in the genetic code has demonstrated that swapping these synthetic base pairs out of the normal code or adding them usually produces unstable results (Zhang et al. 2017).
(optimisation)

Once sufficent common ground is established on the basis of knowledge that can be reasonably assumed to be common to Earthlings and extraterrestrials (e.g., elementary mathematics and physics), it is possible to convey contingent facts about human customs.
(inference. common ground)

in the late 1990s, Ollongren set to work designing a second-generation Lincos that was multileveled and based on logic rather than mathematics. For Ollongren, logic has a distinct advantage over mathematics as a basis for a lingua cosmica because it can describe the logical content of a text, as well as the definitional framework of the system.
(logic)

Both spacecraft are currently headed out of the solar system at around 25,000 miles per hour, but even at these blistering speeds it would take the Pioneer probes around 80,000 years to reach our closest stellar neighbor, Alpha Centauri.
(fact)

The ability to convert one form of energy into another form of energy is fundamental for any technologically advanced society, and it can be assumed that an extraterrestrial intelligence capable of intercepting the spacecraft has developed transducers. If they have not, we can’t hope to communicate with them at all because they won’t be capable of radio astronomy.
(inference. energy convert. radio)

[Hallie]

read in berlin

[Yates Buckley · Rating 4 out of 5]

An interesting text that goes through the history of thinking and practical approaches to decide what messages to send to space looking for contact with aliens. The philosophy around the issue is intriguing and the approaches taken range from insightful to simplicistic.

The actual language used in the text could be more fluid and personable but an interesting read nevertheless.

[Fanchen Bao · Rating 3 out of 5]

The book was information rich yet not a very enjoyable read. In my opinion, the content was fine, but the ordering of the chapters could be improved. In particular, I think the Appendices A (The Arecibo Message) and B (The Cosmic Call Transmission) should be placed in the main text because they are not prohibitively technical and provide crucial examples for readers to build context when going through the main text. Speaking from my experience, having not realized the importance of the Appendices, I went through the main text head on and was left confused many times, definitely more than the budget I would allow a dense yet decently crafted book.

Another aspect I think the book could improve upon is to put more emphasis on explaining Lincos 2.0. It can explain lambda calculus more (make it its own chapter if necessary), go through more examples of Lincos 2.0 (in the current version of the book, there are only two examples: Aristotellian syllogism and "Alice in Wonderland on bookshelf #1"), and possibly explain its limitation better. With more examples and patience in explanation, I think everyone would find Appendix D more approachable than it is in its current state.

There were a few instances where I believe errors had been made in formatting. I will document them below. Of course, there is always a chance that I have misinterpreted things and the weird formatting was actually intended.

p215, the definition of D, human, mortality, and Greeks
CONSTANT D: Set.
CONSTANTS human, mortal, Greek: D -> Prop.

p216, the Lincos annotation of Aristotellian syllogism
(All x: D)((human x) -> (mortal x)) ^ ((Greek x) -> (human x)) -> (Greek x) -> (mortal x)

p217, typed hypothesis for the definition of factorial
h1: (ALL n: nat)((= n 0) -> (fac 0)): nat
h2: (ALL n: nat)(¬(= n 0) -> (* n (fac (- n 1)))): nat

p218, defining environment
CONSTANTS book, shelf: Set
CONSTANT Alice in Wonderland: book
CONSTANT #1: Shelf
CONSTANT is-book: book -> Prop
CONSTANT is-shelf: shelf -> Prop

p218, reason for BS to require two arguments
[λ x: book](is-book x): Prop
[λ y: shelf](is-shelf y): Prop
[λ x: book; y: shelf](is-book x) ^ (is-shelf y): book -> shelf -> Prop

Interesting and memorable quotes

Notably, establishing contact with Martians wasn't eligible for the prize, as Goguet considered the existence of extraterrestrials on the Red Planet to be "sufficiently well known".

-- p7

...we might detonate the world's nuclear arsenals on the far side of the moon...it might communicate to an extraterrestrial observer of the blast that there is a civilization in the milky Way... Yet we likely wouldn't consider this to be a message to the extraterrestrial, since a message connotes the use of language, and hence, the conveyance of a though.

-- p25

Minsky argued that this is the real key to our intelligence insofar as it allows us to represent prior thoughts as objects of another thought, a mental trick that manifests as recursion in natural language.

-- p35

The term for an image that bears a physical resemblance to the thing it represents is an "icon", whereas an image that has an arbitrary, conventional connection to the thing it represents is a "symbol".

-- p139

[Nestor · Rating 3 out of 5]

I wanted to read this book since I read The Great Silence: Science and Philosophy of Fermi's Paradox, talked, not very well though, about the Fermi Paradox. The book title Extraterrestrial Languages is a little bit misleading since the book doesn't deal with deep speculations about how could be the way that alien beings could have constructed their languages, more it deals with our attempts to send messages to them. Language is complex, we can't even understand old Egyptian languages without the Rosetta stone much less try to imagine what and how to communicate, but the author describes those efforts.

- Increasing the likelihood that an ETI within 100 light-years will be able to detect and extract the information content of an interstellar message would require continuous broadcast times on the order of several months or even years. ---> Maybe that's why we have not listening anybody either.

- Whereas SETI is approaching the ability to do all-sky surveys across millions, or even billions, of frequency channels (Garrett, Siemion, and van Cappellen 2016), interstellar messaging requires focusing on a single star and broadcasting on a narrow range of frequencies at a time.---> If is "energy intensive and expensive" why shouldn't be for them Even if it is a Type II or Type III civilization why consume energy on this instead of themself? Right?
- A full discussion of message content is beyond the scope of this book---> That's why I give it 3 stars.

[Bethany · Rating 3 out of 5]

This was a good book that made me read thoroughly. I was familiar with SETI, Frank Drake, the Drake equation etc before reading and as I read learned more of the history of METI and our quest to make contact with extraterrestrial life. It's an interesting pursuit and so human of us really.

"...interstellar messages that contain natural language presume that the extraterrestrial recipient possesses a functional equivalent neurobiology." (p32) This quote stuck with me, especially as this concept was explored through the rest of the book. One of the challenges of communicating with or towards ET life is how have they evolved? How do we send a message they will be able to understand based on their knowledge systems of language, science, math etc. Makes me wonder if we have been sent messages that we are unable to decode or recognize.

[isaacq · Rating 4 out of 5]

a surprisingly engaging narrative about the handful of scientists who have toiled over the last 100 years to formulate the perfect message to send up into interstellar space. this book is mainly about the sequence of developments and how they informed future refinements. a quartet of appendices delve into the "languages" themselves, if that's what you came for.

while the tone is almost perfectly neutral, this book really got me thinking about logic, semantics and (to a lesser degree) diplomacy.

[Pablo Flores · Rating 4 out of 5]

This is a quick, informative tour of the history and the theoretical and philosophical dilemmas of SETI (the search for extraterrestrial intelligence) and its less-known cousin METI (messaging for extraterrestrial intelligence). It does a good job of presenting all the competing views and doesn't gloss over technical details, although most of that is left for the appendices.

[Marc C · Rating 3 out of 5]

Interesting exploration of the history and technical and communicative obstacles of trying to contact extraterrestrials. The two big problems are “how will they notice the signal?” And “what constants and commonalities might we use to establish a quasi-language?”

Dense and dry at points, which I skimmed. Read it if the subject interests you, skip if not.

[Jeremy Edwards · Rating 5 out of 5]

I really enjoyed the book however I do think the title could have been different as it implies discussion of how alien languages would function but nonetheless a greatly informative read on the problem of interstellar communication

For a book on how aliens might communicate, check out the book Xenolinguistics. Do note that it’s a linguistics book, so it’s not light prose at all.

[Carmelo Valone · Rating 5 out of 5]

A brilliant history of our own human attempts to send messages out into space and that of how to create a message that might be better understood and of course some diverse learning lingustic models.

Also please note that this book is Real Science! And not some History channel kookery!!

[Zac Ori · Rating 3 out of 5]

This is probably closer to a 2.5 for me. There's a lot of interesting stuff here, but the text is a little opaque at times. I also wish the author had considered more what kinds of messages extraterrestrials might want to send to us rather than only thinking of how we can initiate contact.

[Brian · Rating 5 out of 5]

Per linguam ad astra.

[Miguel · Rating 3 out of 5]

The book should call itself human language instead 🧐

[Andrew Bahle · Rating 2 out of 5]

Just not written in a very engaging way in my opinion. May return to look up a fact or two.

[Kelly Burke · Rating 4 out of 5]

This was a fascinating book all about the difficulties and constraints involved that I would have never realized on my own! While it seems written for anyone to be able to pick up and understand, the book does get a bit technical (but you can also skip the details if that's less interesting to you) and sometimes it seems to go off on tangents. It was a fairly fast-paced book that addressed all the aspects involved in communication strategies. Sometimes very engaging, sometimes bogged down in details.

[Kerry Pickens · Rating 4 out of 5]

This book is written by a journalist, not a researcher or a paranormal enthusiast. It details the history of the founding of National Science Foundation after World War II, and the interrelation between linguistics theory and the broadcast of messages into space. There was quite a bit of debate as to whether we should try to send out messages as some people were concerned that we would attract attention from other beings that would not end well. Reading about the paranormal and people's fascination with it is a guilty pleasure of mine, plus I live in New Mexico which is Grand Central Station for paranormal activity. The assumption the scientists and the publics attempt to communicate (like SETI) focus on life on another planet. They do not seem to be aware that extraterrestrial life is already here and has been for a long time. Why are we looking for it in outer space? If you are interested in personal experiences with paranormal activities, watch the episode of Unsolved Mysteries called Paranormal Rangers. You can learn more about it here: https://www.netflix.com/tudum/article...

[Nat]

This usefully complements Akria Okrent's excellent In the Land of Invented Languages and poses questions about the constraints on languages used in METI (messaging extra-terrestrial intelligence) including broadcast frequencies, whether they should aim to include instructions for their own interpretation (I'm not sure this is going to work!) and whether or not we should even be sending these messages out in the first place.

[Michael · Rating 3 out of 5]

Subject is better handled by a better writer with Paul Davies - The eerie silence

[hervois · Rating 4 out of 5]

titre trompeur mais livre fascinant.