In Star Trek, there are universal translators on the ship to make communications between the different species possible.

But there are countless times when Klingons talk in Klingon and English, when Picard quotes French or Latin, when characters say a few lines here or there in some foreign tongue to show they know the language.

Why doesn't the translator translate these phrases, too, if all other languages are instantly translated?

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    Always thought about this too!
    – Peter
    Commented Oct 20, 2011 at 18:09
  • Reminds me of this (starting at 0:20): youtube.com/watch?v=3gUL-3rVmNo
    – Till B
    Commented Oct 21, 2011 at 6:50
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    The universal translator is used so every episode isn't "Hey we can't understand these people. Lets stay here for a few months and figure out what they just said". It doesn't need to make sense. Commented Jun 23, 2016 at 1:55
  • How would you translate "Gemütlichkeit" into Klingon?
    – Spencer
    Commented Apr 9 at 22:50

6 Answers 6


From http://en.memory-alpha.org/wiki/Universal_translator (Which got it from TOS 2x02: Metamorphosis)

Responding to Zefram Cochrane's question about the theory of operation, Kirk explained that there are certain universal ideas and concepts common to all intelligent life, and that the translator compared the frequencies of brainwave patterns, selected those ideas it recognized, and provided the necessary grammar. Kirk further explained that the device spoke with a voice, or the approximation of one, that corresponded to the identity concepts it recognized.

Since it's already scanning brainwaves, presumably it can also detect intent (whether you want to be understood or not), and decide whether or not to translate as appropriate.

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    Wow - no wonder the Federation doesn't have any crime - they have Pre-Crime Detectors.
    – John C
    Commented Oct 21, 2011 at 12:30
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    This is completely inconsistent with the TNG episode where they meet the species who communicates only in metaphors - the meaning behind those metaphors is clear, but the UT only translates the words.
    – Jeff
    Commented Oct 22, 2011 at 15:43
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    @Jeff: You're assuming their brainwave patterns were similar to general humanoids.... Like how Betazoid's can't read Ferengi because of their brain structure, there's a good chance the UT couldn't correctly interpret the Darmok aliens' thoughts because it had nothing like that to compare to.
    – Izkata
    Commented Oct 23, 2011 at 22:34
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    I don't remember about Troi, and was just using her as an example that neither is infallible. And the Ferengi have their own UT that actually goes both ways (DS9: Little Green Men), so that may be a moot point.
    – Izkata
    Commented Oct 24, 2011 at 13:56
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    The brainwave thing is just impossible: scanning the brain of a race you've never met, understanding how it works, expecting it to use "brainwaves", knowing which of those waves controls thought and speech, figuring out what the waves mean. And it's not just translating broad thoughts, it's getting every nuance and words, as the translation is often very eloquent. It's just absurd. Commented Jul 14, 2012 at 18:12

I don't buy the brainwave explanation. Aside from it being nearly impossible, it doesn't fit in with the rest of the show.

It would have to scan the brain of a an unknown race, understand how it works, assume it uses "brainwaves", know which of those waves controls thought and speech, and figure out what the waves mean. And it's not just translating broad thoughts, it's getting every nuance and word. The translation is often very eloquent. It's just absurd.

And most importantly, it requires mind-reading at a very deep level. Nothing else in any of the series suggests the Federation can read minds. They would have used that for many other things (e.g. is a suspect lying?, is this guy on the viewscreen bluffing or is he going to fire, is my crewmate a clone taken over by an alien). They wouldn't need Troi to guess using fuzzy feelings (they would also be able to hear telepaths telepathing).

The universal translator does not read brainwaves.

While the brainwave explanation was mentioned in one TOS episode, everything else in every other series has clearly shown it's a language learning process. ENT covered this a lot and showed the fallibility of earlier technology.

So How Could It Work?

There are two parts to this. First, is the theoretical nature of the translator and what it would do if you were using one. And second, what we, as viewers, hear and see (subtitles) for storytelling convenience.

Single Race Present - Speaking Own Language

When a race is by itself, with no aliens present, a translator could determine that and not translate. As viewers we may see subtitles or we may hear English. But we can assume no translation is happening.

Multiple Races Present - Speaking Own Language

When multiple races are present, each speaking their own language, the translator has to hear what you're saying, translate it into every language of those present, and alter the sound wave in the direction of each person listening. We saw this on VOY when they found Amelia Earhart.

Sound research today can already completely block out sounds with alternate waves and project sound in very precise directions. So it isn't hard to imagine the mechanics of this working in a few hundred years.

A translator can accurately determine those present and what language they speak based on their race. We've seen the translator mess this up before when a smaller group of people of a particular race speak a different language. So it can determine you're human, and decide to use English, but can't determine if you're a human that doesn't speak English unless it hears you speaking first.

It would be easy enough to determine (or at least predict very accurately) who you were speaking to in a room based on vocal and body cues. If you're Vulcan near another Vulcan and speaking directly to them, it could choose not translate. We see this sometimes when a Klingon captain will turn to one of his crew and shout a command and we, as viewers, hear it in Klingon (sometime with subtitles), even with people from other races around. We can assume the translator didn't translate this.

Any Race - Speaking Another Language

With all that in mind, it's easy to see how Picard can speak French, or Hoshi can speak Denobulan. The translator knows your race and what language you speak. When it hears you speaking a different language, it would know that was deliberate and wouldn't translate it.

Personal Translator

Also, it seems at least some translators are embedded in your body (Little Green Men, DS9). A translator could learn your preferences and proficiencies over time (and you could set them as well). If you know a lot of Klingon, for example, it could stop translating things you hear all the time, like greetings.


Where this doesn't work is when two people are speaking another language when someone from another race is around and one of them says something like, "Speak <guest language> around the guest." There is no reason why the translator wouldn't translate if the guest was part of the conversation, and no expectation that any other aliens would speak or even know <guest language>. But brainwaves don't solve this either.

I can't think of any examples other than Troi to her mom, but they're speaking telepathically. So that doesn't really count (but it does show that the translator isn't reading brainwaves).

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    What about Klingons speaking Klingon in the presence of humans/others, all over DS9?
    – Izkata
    Commented Jul 14, 2012 at 16:24
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    @bitmask The show itself contradicts the brainwave theory many times. ENT is full of "language learning" software references. Commented Jul 15, 2012 at 1:11
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    @bitmask They are often working off recordings, too, which don't have brainwaves. Wikipedia: "Star Trek: TNG Technical Manual says that the Universal Translator is an "extremely sophisticated computer program" which functions by "analyzing the patterns" of an unknown foreign language, starting from a speech sample of two or more speakers in conversation. The more extensive the conversational sample, the more accurate and reliable is the "translation matrix," enabling instantaneous conversion of verbal utterances or written text between the alien language and American English..." Commented Jul 15, 2012 at 1:42
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    IMO this is much more convoluted and brittle than the intentionally vague and often lampshaded explanation given in the series. Fluently translating and projecting clear, undistorted audio to everyone in the room using a single chip in the user's ear is no more realistic than the brainwave explanation. Guessing one's language based on race or ethnicity is an even worse idea. As for the brain wave explanation being contradicted, there's no reason to believe that the translator technology Hoshi uses is the same as that used in the 24th century. Commented Aug 31, 2013 at 9:56
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    Plus, there's no reason why a brainwave-based UT couldn't be adaptive in nature. Current "thought-sensing" technologies (e.g. Emotiv) require a period of "training" where the system configures itself to the user's neuroelectrical patterns. There's nothing that says the UT can't require the same. This may not be any more technologically feasible than having a UT chip that can magically tell all the languages you want to translate into when you shout in a crowded room or over a PA system. But it's a bit less contrived. Sometimes it's better to just invoke phlebotinum and acknowledge what it is. Commented Aug 31, 2013 at 10:07

Why doesn't the translator translate these phrases, too, if all other languages are instantly translated?

There are certain concepts in other languages that are so alien to us that the translator is not able to make an approximation.

To give an example. How would you explain Brandenburg Concerto 3 to someone who is not able to hear music, and capture the essence of the song, rather then what is happening?

On top of that you have sentence structure, grammar based on customs, which cannot be determined. For example "안녕" and "안녕하세요" both mean the same thing, but if said in the wrong context can cause confusion or anger in the person you are speaking to. This is why it is mentioned that the universal translator works better the longer it can analyse the language.

In closing, Darmok and Jalad at Tanagra.

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    In addition to untranslatable words/concepts (why many loanwords exist), sometimes using the original word/phrase adds flavor and nuance that is lost in translation. When one says qapla', it isn't quite the same as just saying success; it's also evoking the Klingon warrior culture and other subtle associations. And the phonetic characteristics of the word itself has meaning too. So it would be desirable for the UT to accommodate perceptually untranslated words. Commented Aug 31, 2013 at 10:19
  • However, when the dominion representative was talking and the translator was translating it was making serious mistakes. The genetic augments had to turn the translator off to hear that he was making a request and not a proposition in DS9 episode that dealt with them trying to convince the federation to surrender.
    – v010dya
    Commented Feb 22, 2018 at 7:31

Some phrases simply aren't directly translatable. For example, the German word "Todschlagargument" has no direct English equivalent, and as a result, when it's needed, we use a German loadword. This issue pops up a lot with Japanese food.

Some phrases simply don't translate. Why would this be different with alien languages?

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    But sometimes they are words that should be translated automatically. Worf does this often: he says something in Klingon, then provides the English equivalent immediately afterwards.
    – Wolfie Inu
    Commented Oct 9, 2015 at 6:35
  • DS9 - s05e01: Warf "Even if we do find our way inside, getting close to Galron will not be easy. He's guarded around the clock by his personal security force the Yan Esleth." Dax: "The Brotherhood of the Sword".
    – v010dya
    Commented Feb 22, 2018 at 7:27
  • +1, similarly the german word verfremdungseffekt does not have a direct translation Commented Apr 10 at 8:33

Language is mathematical, so they will establish a base, and with AI, learn the language from other languages. Also, somebody in human language had to learn it from scratch without translation material, being on the okanet, analysing phrases said etc, could all be done by analysing news, literature, music (yes, there is a link to language formation) from the current time to the history of the planet (they would had it digitized). So, when meeting a new species for a first time:

  • solely based on math, language is analysed and a basic basis is established (e.g. hand movements from video, facial expressions from video, tone of voice).
  • this is added to the known similarities between language.
  • after given to access to the species database, a bigger base can be formed.
  • like any language, the more you speak it, the better you get.

Note: theoretically, if the Enterprise analysed the history of the culture in Darmok, it could establish what the metaphors mean and then translate them to English that is structured correctly from our point of view. In terms of sound, the combadge has some directly speaker system to cancel out and project the translations.


I always felt that the Star Trek UT worked directly with the brainwaves. It was similar to Farscape’s translator microbes, it make you FEEL that the other person was speaking in your language. This is actually shown in an episode of Discovery, we hear the Klingon speaking in Klingon with subtitles and once the UT is activated we hear them in English (or whatever human languages is the dub), the Klingon even says “I did not expected you to speak Klingon” and Michael says it is the translator. This would also explain why a Japanese heard people speaking in Japanese in “The 37” and how Picard and Data are capable of going undercover as Romulans into Romulus itself. You don’t really hear anything over the other person’s voice, you hear the person’s voice in your language because the trick is that your brain itself changes the meaning inside your head.

Of course, this doesn’t explains the lip-sync, technically that should still be an issue. But everyone who has seen a dubbed movie (and I don’t mean the terrible bad old times dub of Asian martial art films, but the careful quality dubbing you can see in Western media like between Spanish, English and French) your mind ignores the lack of sync. I guess it could be handwave that unless the language is too different and it takes you a lot of time to say one word your mind just overlooks the lack of sync like watching a dubbed film.

  • This "brainwaves" answer would have to address the inconsistencies pointed out in the much earlier answer from 2012... To name only a major one, if the UT reads brainwaves, then why is Troi or any other telepath entities needed? The Federation has an almost infallible lie detector/mind reader! One that can detect and translate the brainwaves of alien races never encountered before.
    – Andres F.
    Commented Apr 9 at 22:09
  • A system that translate directly into the brain cortex making it feel like is hearing a language on his own is not the same as telepathy, as the translation is still happening post facto. The brain pattern and the thought process already happened. The translator is not reading minds even if the process of translation take micro seconds the spoken word was expressed and came out of the others' mouth, the translator then makes the recipient hear the words in his language which at no point is reading the emitter mind.
    – Daniel
    Commented Apr 10 at 23:20
  • You claimed in your answer the UT is reading brainwaves, which is the definition of mind reading... and the answer I referenced points out the inconsistencies of this.
    – Andres F.
    Commented Apr 11 at 15:12
  • No, I actually places as an example another fictional method used in fiction, the Translating Microbes of Farscape which no one has ever claim are similar to telepaty. In fact it has been compare more with the Babel Fish of Hitchhiker's Guide to the Galaxy. In fact Doctor Who's method (which consist in the TARSIS directly wraping he brain of its user and translating what the user here) would also be similar. In all cases telepaty is not involver you're completely wrong.
    – Daniel
    Commented Apr 12 at 18:31
  • How is "working directly with brainwaves" not telepathy? And how would the UT manage to translate the brainwaves of entities it has never encountered before into a known language?
    – Andres F.
    Commented Apr 12 at 20:13

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