In Hitch-Hiker's Guide to the Galaxy I know you put the Babel Fish in your ear and it telepathically translates any language, and the one from Star Trek could translate languages that the Federation had encountered but had limitations. Basically, what would it take to make a non-organic device that can translate any foreign language it encountered? What would it need to be able to do? Like if an alien from another galaxy arrived in Milky Way space?

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    $\begingroup$ I suggest a human baby. Those little guys are unfairly good at figuring out languages. $\endgroup$
    – Daron
    Jul 31 '20 at 20:59
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    $\begingroup$ The other question is not hard-science. This one is. This one specifically asks "what would it need to be able to do"? The other question asks for a hand-wave narrative prop. $\endgroup$
    – cowlinator
    Jul 31 '20 at 21:36
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    $\begingroup$ A true universal translator is impossible. This is even addressed in HHGttG where it's explained that the "Babel fish" killed God, because it was deemed impossible without divine intervention, thus proving God's existence and setting up a paradox. $\endgroup$
    – Dragongeek
    Jul 31 '20 at 22:07
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    $\begingroup$ @Dragongeek That was a joke; people argued it proved the non-existence of God. The argument is roughly: God: “proof denies faith, and without faith I am nothing”; Man: “but the Babel fish is a dead giveaway, proving you exist, and therefore, by your argument, you don't”; God: “oh, I didn't think of that”. Iirc, Man then goes on to prove that white is black and gets run over at the next zebra crossing. (Canonically, this was just the thesis of a book described by the reliable narrator, and not a true statement of the narrator.) $\endgroup$
    – wizzwizz4
    Aug 1 '20 at 7:40
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    $\begingroup$ This question currently have both [reality-check] and [hard-science] tags, which conflict with each other. Please check their descriptions to choose which one you want to leave and remove the other one. $\endgroup$ Aug 1 '20 at 14:07

The "Babel fish", as described by Douglas Adams, is outside of realm of modern science.

Translating from a previously unknown language, without any references, is an unsolvable task. The original Babel fish worked off "brain waves", not sound waves, which provided a logically conceivable way of translating the meaning of the speech. There was a premise that brain waves are uniform enough for all sentient species that a single organism (or device) is capable of detecting and deciphering them all. So, in effect, underlying brain activity should have been much more common than the language.

If we want to develop an universal translator like that, first we need to prove that brain activity can be read from a distance and translated into information stream that adequately represent individual's speech.

However, if we don't want to develop a telepathic translator, but would be satisfied with acoustic one, the task can be solved with present science, to an extent. The resulting translator, even if powered by a "perfect" AI, would have the following limitations:

  1. The device must clearly hear (and see, if necessary) every articulation of the speaker;
  2. If the language is known, a "best guess" translation is produced (but even the best guess can be wrong). Upon better understanding of specific context and dialect, device can improve the translation.
  3. If the language is unknown, a learning period should follow before any accurate translation can be made.
  4. Depending on complexity of the language and willingness of the speaker (or speakers) to "teach" the device, this learning period can take a while.
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    $\begingroup$ Ideally the datafiles for newly discovered languages could be downloaded from the Internet. Outdated datafile plot hooks abound. $\endgroup$ Aug 1 '20 at 9:04
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    $\begingroup$ My favorite example of AI-assisted translation comes from There Is a Tide by Larry Niven. Louis Wu meets a member of a previously-unknown species. So they can talk, the ship's computers spent a few seconds teaching each other the other's language (at future computer speeds, e.g., it took just a few seconds). Then they were able to converse reasonably, though not perfectly. For me, easily the closest to a scientific handwave for this. (Perhaps let down slightly by the fact both ships just happened to use comm lasers, which was hand-waved as something any space-faring society would use.) $\endgroup$ Aug 1 '20 at 11:42
  • $\begingroup$ This question has the hard-science tag. This answer does not meet that mandate. $\endgroup$ Aug 3 '20 at 4:36

Excellent question, and one that's challenging to linguists and anthropologists. Adding extraterrestrials makes it even more complicated.

On Earth, human languages spread, evolve, and recombine in ways that can be tracked. Languages evolve much the way organisms do, mutating and expending in complexity or simplifying and streamlining. Languages are modified by the values of the culture speaking them and the major historical events and eras preceding them. Many modern languages can be traced back to common ancestors. Most European languages derive from some combination of Latin, Greek, or various Germanic languages. If you study Latin, it's a lot easier to learn Spanish or Italian, for example. So the big question is if you traced all modern languages back would you find a single common ancestor to all human languages? If you did, could you build a linguistic model from it, extended by the languages that evolved from it, and use this to understand every other human language since?

Assume that you could. It's not unreasonable to assume, since all human languages were created by human minds inside human brains with largely identical human emotions, logic, and values.

But, would this extend also to extraterrestrials? If it did, there's two ways it would:

We've communicated before. In the Star Trek universe, human languages share roots with Romulan because they'd visited Earth and taught the humans. Many sci-fi universes follow this Ancient Aliens concept where the basis of human culture (including language) was taught to us by extraterrestrials. The Alien and Predator movies, for example, or Stargate. Flipping it around, several franchises have suggested all languages derived from a single ancient civilization (usually Atlantis) and at the height of that civilization humans were going into space and communicating with extraterrestrials on other planets. In such a scenario, it's not unlikely that we'd plant the seeds for an alien species' language to be derived from ours.

Language is connected to intelligence. Human languages are the product of human minds, but would alien minds be that different? Perhaps there's a linguistic root that most intelligences converge on, much like how many of Earth's animals have converged on similar body shapes. See Carcinisation for a really weird example of this. This sounds really anthropocentric, just assuming humans are the ideal, but there's an argument to be made for it. It has been observed that dolphins form syntax in their communication, not just making noise but actually forming logical constructs from sequences in their clicks. More information from the Dolphin Communication Project. Granted, dolphins are still of Earth, are even mammals, and would likely have brains more similar to humans than some extraterrestrial species.

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    $\begingroup$ +1 for mentioning the Doplhins (the 2nd most intelligent species in Hitchhiker's) $\endgroup$
    – Tom
    Aug 1 '20 at 9:04
  • $\begingroup$ This question has the hard-science tag. This answer does not meet that mandate. $\endgroup$ Aug 3 '20 at 4:36

a Universal translator at first glance is impossible

Lets say I send you a binary string "00010101" translating that to base 10 is simple. 21. But then I tell you that it is in big endian notation, and the actual answer is 168. But I actually mis-translated this because it was supposed to be in unary, so the value is 3, ect, ect.

If you don't know the standards of a language there is no way to intuit from meaning from any sequence without context

You can still have translators

Lets say you have 100 years of radio chatter from a civilization that you collected while in hyperspace to a civilization. first you can have the computer identify patterns and attempt to locate a language teaching broadcast. This will start with a low set of words and increase in succession. you can then guess words and cross reference with the other radio audio you have.

A computer can also easily identify patterns and determine the grammar and syntax of systems, the computer can then create graphs of related words and based on known statistical patterns to guess the meanings of words. Any words that you have and they don't can be replaced with approximations based on known language.

If no radio transmissions exist, you can just monitor conversations secretly and compile data like that. doing this in secret is very important since if you are making first contact then "what the fuck is that thing in the sky" will have the same statistical frequency and placement in sentences and complex greetings, which might throw off you algorithm a bit.

  • $\begingroup$ One issue for translating based on radio broadcasts alone is that they lack all context. You could potentially build a dictionary of words and phrases and determine the grammatical rules of the language, but you would have no way to infer the meanings of those words without having context (at best you could get greetings and farewells because they would often occur at the start and end of a conversation). Context is what physically monitoring conversations is for. $\endgroup$
    – BBeast
    Aug 1 '20 at 11:59
  • $\begingroup$ How do you convert an arbitrary radio wave to sound? Is it encoded using amplitude modulation, frequency modulation, or something more complicated? Does it use some spread spectrum technique? Which frequencies represent different parts of one signal and which are different signals? There are many parameters that we regularly vary, and many more that we could vary if we had different problems to overcome (as an alien civilization might). Oh, and all this is just how to straightforwardly represent sound with a radio wave and doesn't touch on obfuscation or encryption. $\endgroup$
    – Extrarius
    Aug 1 '20 at 14:21
  • $\begingroup$ You don't convert to sound waves, you would only be dealing with the arbitrary waves. you would need to convert to sound waves when you get there after finding a radio. $\endgroup$ Aug 2 '20 at 17:14

Cochlear implants and AI

Normal hearing is a thing of the past. cochlear implants can catch the sound over many frequencies and be stronger than the normal ears. This can prevent hearing loss from loud noises and if they do break they can be easily replaced. cochlear implants listen to sound and then translate it to electrical stimuli which is sent down the nerves.

All sound is monitored. If a language us detected the person doesn't know, it'll translate it for him before it's added to the sound stream. If an unknown language is discovered, it'll use an AI database with all known languages to infer what the aliens are saying. Inflection and such are also in there. It'll start difficult, but an AI with such a large database will be able to crack alien spoken language. There might still be some problems with vast cultural differences, but nothing is perfect. Possibly camera's can be added to see visual queues to the decoding of the language.

  • $\begingroup$ What is "cohear"? Did you mean "cochlear"? $\endgroup$
    – Matthew
    Aug 1 '20 at 13:54
  • $\begingroup$ @Matthew yes I mean cochlear. Thank you. $\endgroup$
    – Trioxidane
    Aug 1 '20 at 14:33
  • $\begingroup$ This question has the hard-science tag. This answer does not meet that mandate. $\endgroup$ Aug 3 '20 at 4:36

The answer should be Universal Meaning. Every language (even those that use pictures, splashes or thinking) have to express something meaningful - like I am hungry, Cold in here, or even much more complex thoughts.

So every language should be translated into UM and after that into new language.

Phycicaly, you will have to measure the sounds, body language with camera, and everything possible (body temp,..) that will make you closer to real meaning.

  • $\begingroup$ This question has the hard-science tag. This answer does not meet that mandate. $\endgroup$ Aug 3 '20 at 4:35
  • $\begingroup$ One problem is different ways of thinking. I wish I remember where I read this (I think Larry Nivens, but am not sure). We define ourselves with "I think therefore I am," but what if the alien thinks of himself as "I eat therefore I am," or "I perceive gamma rays as a shade of purple." $\endgroup$
    – NomadMaker
    Oct 16 '20 at 22:44


While it is possible to generate a translator for known languages, given a large enough database, grammar rules, some form of AI etc. there are two impossible hurdles to take for a universal translator that can also translate unknown languages.


Given an arbitrary word from an unknown language, there is absolutely no way you can figure out what it means. Imagine the alien looks at you and says "Grublxkn". That could mean virtually anything and you have nothing to figure out which of the many options are true. It could be a greeting, a threat, a question, its name, its term for your species, or it could be completely unrelated to you.

In human languages, we could find a near relative and make an educated guess from there. If the word sounded spanish or the speaker looks spanish, and Latin is in my database, I would have at least some information to draw on.

Also, when we learn languages, we learn them with references. Parents don't simply repeat a word for a child until it understands. They will point at various dogs and say "dog", giving the child a reference to associate the word to.

With unknown languages and alien races, no such luck.


Language and thought are related. To the point where some (e.g. Sapir-Whorf) say that you can't think what you can't say. An unknown alien species could have entirely different thought processes and thus entirely different language that does not follow any of our known rules of grammar or structure. The movie "Arrival" explored such a scenario, though in a very simplistic way (in the end, the aliens had words and sentences, anything else would've been too heavy for a movie audience I guess).

If someone thinks different from you, and his language has expressions that yours simply lacks, there is a translation problem. We see a bit of that even in human languages, especially in poetry. Sometimes you need two or three sentences to explain a single word (japanese is famous for that). Expand this to grammar - for example some languages allow you to express in a grammatical case whether what you are saying is first-hand knowledge or you only heard about it yourself. And that's human to human language translation. It takes experts extensive study to be able to halfway properly translate between those. No amount of tech or AI will let you make a translation from an unknown language with different rules based on a few words, phrases or sentences. There's just not enough information in that to understand the structure and meaning, much less to build a dictionary.

Even building a universal translator that over time learns a language the way children do would face this obstacle. What tells you that aliens learn their language the same way?

note: apparently, some readers miss the irony of answering a hard-science question with "magic". So to be utterly clear: What that word means is simply a shorthand expression for: No product of science or technology within the imaginable or even slightly hand-waverium, unobtanium based sphere will be able to produce such a device.

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    $\begingroup$ "you can't think what you can't say" - That is the strong version of the hypothesis and is way outdated by modern studies. Some birds, apes, and dogs, can work out quite complicated puzzles without speech. $\endgroup$ Aug 1 '20 at 10:06
  • $\begingroup$ "Grublxkn". That could mean virtually anything --- unless of course it is holding a pointer and touching various objects as it names them. Young humans do this sort of learning from birth. $\endgroup$ Aug 1 '20 at 10:09
  • $\begingroup$ Magic doesn't satisfy the requirements for a hard science answer $\endgroup$
    – L.Dutch
    Aug 1 '20 at 11:30
  • $\begingroup$ Sapir-Whorf was debunked so long ago, but people talking about language shouldn't mention it. You lose credibility points by doing so. $\endgroup$
    – a4android
    Aug 1 '20 at 12:23
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    $\begingroup$ @Tom, the hard-science tag "Requires answers backed up by equations, empirical evidence, scientific papers, other citations." I don't see any in your post. Hence, it fails the requirements of the tag. Note that I downvoted everyone who failed that tag and posted a comment explaining why. $\endgroup$ Aug 4 '20 at 13:47

A true universal translator requires omniscience, mostly because "language" is just a societal construct. Say two friends get together (say Jane and Alice) and invent a couple new words so they can communicate in secret without others knowing what they're saying: that's a language (albeit a very primitive one).

For the universal translator to properly translate what Jane and Alice are saying to each other, it would need to know everything that Jane and Alice know. Now, for humans, you could conceivably make this translator some sort of mind-reading device that scans nearby brains for information, but what happens when Jane and Alice start using their language outside of your presence? What if you simply hear an audio recording of them talking, and their brains are nowhere near?

This is why for a truly universal translator to work, it would need to know everything about the entire history of the universe up until the present to function properly.

The only "hard science" or "science based" method I can think of to make this work is if you buy into the simulation hypothesis where you believe that our entire reality is a simulation. In such an environment, advanced technology could conceivably interface directly with "God" aka. the system administrator and request knowledge to make the universal translator work.

  • $\begingroup$ This question has the hard-science tag. This answer does not meet that mandate. $\endgroup$ Aug 4 '20 at 13:48
  • $\begingroup$ @JBH the simulation hypothesis is hard science. Serious physicists and other intellectuals have written serious papers about the concept and it's similar to other high order physics theories. $\endgroup$
    – Dragongeek
    Aug 4 '20 at 15:00
  • $\begingroup$ The hard-science tag mandates that you do more than simply link to those papers. You're required to bring that information into your answer. However, to be frank, the simulation hypothesis is just another way of saying "use magic." Even if I believed that met the letter of the law, it doesn't meet the spirit of the law. $\endgroup$ Aug 4 '20 at 20:41

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