A message arrives from several light years away. It is a complete prepared document, not a two-way communication.

The document can contain line-drawings and diagrams, both 2D and 3D, plus movies (a time dimension) and overlays.

Now it’s straightforward to teach the syntax and encoding through careful examples. It can talk about polygons and such that it illustrates, and recognisable depictions of things we know about like our solar system and immediate stellar neighborhood. So we can understand the names for specific objects, properties of those objects, etc. From mathematical examples we know about category containment, and using our own solar system as a Rosetta Stone we learn words for various properties and how they are expressed. So, we can then understand when they mention, for example, a planet named label with a particular mass and radius, that we didn’t know about before.

To recap: categories and properties are learned from known examples, and can then be applied to other things.

But how can they communicate an idea like “like” or “desire”? How can they teach the words needed to convey a polite invitation?

It’s easy to describe a navigational course. But how to say “the ship you make should follow this course”? And given that it’s possible, how do they say they would “like” us to visit? That is, a polite invitation rather than a demand?

By “polite” I don’t mean usage of diplomatic protocols and rituals, which they cannot know. I mean that it is a request (not a demand) and they would be happy for a visit, but we are free to decline.

Although the sender is a powerful KⅡ or higher civilization, they are just passing through at 10% c, and don’t know us in detail — only what they can see from 10’s of light years with enormous synthetic apertures on the order of half a light year.

  • 3
    $\begingroup$ This seems like a bit much to ask for. Perhaps you would like to see what Nasa has to say about communicating with aliens. Several chapters are relevant to this topic. $\endgroup$ Commented Feb 8, 2017 at 6:29
  • 1
    $\begingroup$ Also, on a related note: the fact that we have not decoded several "lost languages" of human origin is strong clue that this task is likely quite a bit harder than you might otherwise think. First contact language learning is heavily dependent upon two-way language efforts to get feedback and refinement. $\endgroup$ Commented Feb 8, 2017 at 6:34
  • 3
    $\begingroup$ Note that this is being sent with the intention that the reader can figure it out. It's not a random page from an accounting ledger or junk mail that just happened to survive the ages. $\endgroup$
    – JDługosz
    Commented Feb 8, 2017 at 6:38
  • $\begingroup$ The OP's comnent refers to what is called Anticryptography. Messages that are deliberately sent to be decoded by a recipient who doesn't know the code or the language of the message. $\endgroup$
    – a4android
    Commented Feb 8, 2017 at 11:12
  • 2
    $\begingroup$ Its worth pointing out that the voyager plaques were shown to a great many earthlings, and none of them could decode the meaning :p $\endgroup$
    – Innovine
    Commented Feb 8, 2017 at 15:08

7 Answers 7


I don't think they actually need to communicate this explicitly; the invitation will be implicit in the message.

The message must be aimed directly at earth for us to be able to receive it, so the navigational informational will also be specific to us - a depiction of a ship traveling from earth to their planet, for example.

If they have sent us specifically this course, we can reasonably assume that it must be either because they desire us to follow it or desire to tell us to never follow it. Since we would not even know about their existence if they hadn't sent the message, we can reasonably assume that they are not telling us to keep away, and so implicitly a message that outlines a navigational course from earth to their planet must be an invitation to travel that course and visit.

So long as the aliens can assume we will interpret the message as showing a ship traveling from earth to their planet, they can reasonably assume we will understand it as an invitation to visit.

Edit: If you actually need them to teach us their language and make the difference between a polite request and a demand explicit (for story reasons, perhaps), then I'm not sure it's possible. If it were a human language, the only way I can imagine this could work would be showing video/cartoons of situations of language use where it is obvious from context (facial expressions, other people's reactions etc) which are polite and which are impolite ways to say something. But without a common cultural or even biological frame of reference I don't see how it could work with an alien species. I think interaction would be the only way to do this.

Response to question edit:

By “polite” I don’t mean usage of diplomatic protocols and rituals, which they cannot know. I mean that it is a request (not a demand) and they would be happy for a visit, but we are free to decline.

Again, I think this is implicit in the message itself - is there any way that it could be a demand? To demand there has to be some way for non-compliance to be enforced, which would presumably require them to visit us. If they are unable or unwilling to do so then a demand would be empty.

Communicating that it is a demand would probability be easier than that it is optional - a tree-diagram of possible future sequences of events 1: "receive message, humans travel to them" 2: "receive message, humans do not travel to them, they travel to earth." Perhaps they could communicate that it was optional by adding a third option 3: "receive message, humans do not come to them (then nothing happens)" and by showing option 2 as being crossed out in someway?


Informational maze

Imagine it is mosaic mosaic mosaic .... n times ... mosaic of datasets and that tree of those mosaic/datasets it is just one of the possible interpretations of the main dataset send by the aliens. The same way as you may have an encrypted message, which is compiled in the way that there exists set of m keys with decodes the encrypted message in m meaningful texts.

Each time you decode one layer of the alien message it gives you x new keys to dive deeper in the message.

The data sets are any data sets - images, texts, schemes, math, models, whatever it might be.

Let say in the data set there is $n$ layers and $m_n$ possible keys in each layer. So potentially the message can be interpreted in $(m_n)^n$ meaningful ways.

enter image description here


On the picture, especially when it is small we see something which for us looks like something similar to eye picture, the human eye. So for a human, it can be a meaningful information, but for someone else is just mosaic from smaller pictures(data sets) which in the particular case are different eye images but it can be any images(data sets).

So, not a human will not get a human key in the layer and the layer will be kinda transparent for another alien(not human), most likely for an alien the piece of information will be just a data set with no layers in it(they will not see that it is the picture of the pictures).

But a human will see the eye and it might be a key to interpreting the data set in a human way and as result get next human oriented layer of the information.

Alien sees nothing here, except - yeah there is some kind of information, we understand that but we have no clue how to interpret it, and for them, the particular piece of information will be the dead end in decrypting the whole set.

Which keys get those who decrypt the main data set will depend on who they are. And the whole dataset with all those layers will form an n-dimension maze, and the path trough the maze will be different for different species, humans, rocks whatever - those who decrypts the information.

And that allows the aliens to encrypt different information for different aliens, in one message.

Beauty is in the eye of the beholder

Which information opens depend on the interpretation, the particular combination of keys, and probably the sequence in which they were obtained - all that will determine the result, the "message".

But what if one sees let's say 2 keys.

enter image description here

On the picture, it is the matter of your own preference what to see. You can interpret it in any way (there is a lot of such pictures on the internet I just took first from the list). There 3 sets of stories about the picture, one set perfectly fit one interpretation, one set fit another interpretation, one set which fits both or neither.

Same is with ideas interpretations, the story Shakespeare in the Bush - true or not, but the difference in interpretations of an idea may lead to different actions.

Same story in any dataset. One can see the things he likes to see in the data set. And may prefer one interpretation over another interpretation, by working with the information which he likes more. The choose can be conscious or unconscious it is not important, but the choice itself defines the preference of the decoder.

By !preference we define not preferred stuff and do it the same way trough the moving on the path of preferences maze.

The aliens can create the message for different types of aliens, even without knowing them, possible with the use of the modeling system from another alien related answer Aliens are on their way. What can cause them to not understand us?

So yes, if aliens have emotions, we can transfer them the message which will have the proper translation of emotions, including our translation of politeness into their emotions and concepts.
So yes it is possible to send emotions, and do it even in the way they will not think that you smile but have a knife in another hand.

But mostly I agree with @Tharaib's answer, it is complicated and not very much needed.

Send them information about presence - polite invitation

Send them schemes of a magical power device, working in the way they will discover later, after they will have critical mass of those devices, that it will explode in 100 years all at once - it will be kinda demand - you have 50 years to fly to us, and try to get proper information how to stop collapse of your civilisation, your move.


It is possible that after decryption, there will be a hologramme of George Washington in his national costume on pure english(better than my) will polite invite the human civilisation to the aliens.

  • $\begingroup$ I really don't see what nested mosaics have to do with communicating an idea like “like” or “desire”. $\endgroup$
    – JDługosz
    Commented Feb 14, 2017 at 6:42
  • $\begingroup$ @JDługosz images are used just as a representation of the idea and are not the idea itself. Graphical data, in the case visual data, is just a data.(even that most of our ideas can be represented in graphical form, by typing letters, drawing schemes, reproduce paintings, printing notes - but it does not have to be a graphical representation, just digital as we say in 21st century, or hologram, or quantum system). With million years record, I failed miserably to represent the idea, this time it seems I was better, but it seems it is the maximum I can do in this try. $\endgroup$
    – MolbOrg
    Commented Feb 14, 2017 at 8:43
  • $\begingroup$ I think you’re trying to answer something other than what I’m asking here. $\endgroup$
    – JDługosz
    Commented Feb 14, 2017 at 16:16

Aim at the basics of life and hope that life is somewhat universal.

If I show you a video of a creature eating and then excreting, I can probably get across to you the biological need that the creature has for that food -- especially if consumption of food is common across life forms. Then I can work from there.

a) Fear. Show another creature eating the carcass of the original creature. Show it excreting. Then show it stalking one of the original creatures, and show that creature running away. Do this with several pairs of species.

b) Desire. Show the original species, trying desperately to reach a just-out-of-reach piece of food.

c) Animosity. Two animals fighting over the same piece of food.

And so on. If you do this with enough different creatures, we would hope that they would see the analogy and focus on the commonality across the videos instead of the aspects of any single video. By recognizing the value of food, they can probably extract the sentiments around it.

It may be less successful if they're a bunch of sentient plants who never compete for resources sentiently, but even there, we could reasonably hope that they have animals on their planet and can compare the behaviors.

  • $\begingroup$ The civ sending the invitation are very cosmopolitan, having met many visitors before. They can use enough different examples so we don’t have to relate to all of them. They can assume that the recipient is “mobile” enough to develop technology and marshal global resources, if a visit is to be a possibility anyway. $\endgroup$
    – JDługosz
    Commented Feb 8, 2017 at 7:25

A commonly understood way to share a concept or idea is by extending an example of it first. To show politeness to a civilization they do not know much about, they can first share information about themselves in the message, choosing images and concepts about themselves that they value highly and that they interpret to be welcoming and polite by their own standards. This can be followed by the directions to their location. Although very simple, the message would be clear:

This is who we are. This is where we are.

Having the communication end there is universally understood by the recipient of the message that the next step in communication is up to them to initiate, just as it would be understood during in-person communication. It would be unusual to interpret a message extended this way as a demand to come visit.

They also do not need to worry about if their customs and values will be offensive to a civilization that would interpret them that way, because if so interpreted, then the recipients of the message simply choose not to go visit. If, on the other hand, the message recipient finds connection with the alien culture and can understand and correctly interpret what was extended as polite and welcoming, then those message recipients might choose to visit.


Ways to communicate "come here" -

Human - Earth
Bobites - Bobia
Human - Bobia

Human - Earth
Human - Mars
Human - Travel - Earth - Mars
Human - Travel - Bobia

This would work and is a good assumption that the translation is "Humans travel to Bobia".

You will have also had True/False, numbers and atoms already translated in this as well as some logic functions so there are things that you would use from logic like...

= = IS
+ = AND
FALSE = NO/Negation

So message might read:

FALSE BOBITES [travel/move] (to) EARTH
TRUE HUMAN [travel/move] (to) BOBIA

A question might be phrased more like:
HUMAN [travel/move] (to) BOBIA TRUE FALSE

The True at the beginning only means "We want" because we are assuming that normally the statement would not have True at the begging. And we'd also assume that if they wanted to tell us something is true they'd make the statement "blah blah blah = true" or reverse for "true = blah blah blah". The = making it clear we're saying IS rather than a preference statement

But really you could get a lot more sophisticated than this because I'm doing it off the top of my head, but you have pictograms for things like "over" "under" "to" "away". You likely would have a symbol for star which would double as "light" too.

Basically to do this you would have to deconstruct language and then build it back up. This isn't too hard. You just have to use pictures for actions with a symbolic name for that action then write what you want using logic symbols and these verbs. It would likely be crude, but you could do it with a little effort. You would have to be careful with "give/take" and some others because it is easy to consider the whole of the action rather than separating them into give and take. But over all the only issue is the risk of misinterpretting, but thats a risk with all translations and lanuages, even perfect ones.


In my story, I plan to do this by using parables.

Starting from a base of diagrams, geometry, math and logic, and phyeical size, mass, motion etc. from labeled drawings of the recipient’s solar system, it will start out describing the purely physical characteristics and behavior of several groups of animals.

The animals are simplified cartoon characters, having just the needed features for their respecive niches. A sketch shows that it has digestive system, circulatory system, central nervous system, limbs for manipulating the environment, etc.

Then various scenareos are given where the animals do their thing. It will be clear that they need to engage in survival activity, with certain conditions being manditory for survival and broader conditions being desirable.

As a prerequisite, the idea of a computational device is explained. Examples include clockwork, electomechanical devices, photonics, fluedics, semiconductors, etc. all shown as being described by logic gates or mathmatical rules with equivilent algorithm descriptions.

So, it can note that the animal’s brain has a state, with storage of memory and evaluation of inputs and decision making.

A set of descriptions is ascribed to the brain. These will be understood by the reader as being moods or emotions or however they think of such things, even if that’s different from what we can imagine.

The cartoon animals are seen to have goal directed behavior to promote success of the species, with long term survival goals and short term immediate goals.

We (for example) would label these descriptive symbols with words like “want”, “fear”, “pain”, “happiness”, etc.

So, simple animals “desire” food, shelter, mates, etc. and are “happy” when such a goal is acheived. Then advanced social animals are “happy” when cooperating and communicating. Then technological beings are “happy” when crafting a new tool or creating art.

By starting with pure goal-directed behavior, the same terms can then be applied by analogy to successivly more advanced species and abstract reasons.

So when they code “we desire…”, the reader can trace the meaning of that from analogy with situations that are more optimal without being matters of immediate survival, like access to rich food sources for exploting over the coming season, for a preferred mate, for a meeting of representatives of two tribes when they are each doing just fine and not in direct competition with each other.

  • $\begingroup$ "A set of descriptions is ascribed to the brain. These will be understood by the reader as being moods or emotions" there start a problem. The cartoon animals video - how much emotional attachment do you have to them? They are just robots with understandable logic, but they do not have emotions. $\endgroup$
    – MolbOrg
    Commented Feb 14, 2017 at 9:03
  • $\begingroup$ We as humans have a habit of animating different nonliving systems, but not all of us, and why unknown civilization should do the same. "not in direct competition" - can be translated, I do not care about you because of you are irrelevant for my existence. So basically they say they do not care about us, what!!???!!!, we are the strongest you like us to make care about us, no problem, tnx for letting know about your existence - Blood for the Blood God! Skulls for the Skull Throne! $\endgroup$
    – MolbOrg
    Commented Feb 14, 2017 at 9:03
  • $\begingroup$ The idea of goal-driven behavior exists regardless of whether you have the same concept of emotions. $\endgroup$
    – JDługosz
    Commented Feb 14, 2017 at 16:20
  • $\begingroup$ Goal-driven, yes, true, sort of(btw, if you saw the video those creatures have no goal-driven behavior, I'm pretty familiar with the code of the simulation so I can say for certain). But if we are talking about setting the goals then it is a less complex task than transferring politeness or emotions. Overall what you wrote possible will work with humans, and easier to describe to reader. $\endgroup$
    – MolbOrg
    Commented Feb 15, 2017 at 10:50

If they know about our (humans on Earth) existence and want us to visit them, they must also know our biology and customs in details. You do not send an invite letter on millions of drones, randomly in the galaxy.

A map of route from Earth to their planet, with a smiley face and heart sign would convey the message particularly well.

A video of a welcoming party, waiting for guests would also help. If a civilization is advanced enough to interpret their message (as in, to interpret where the planet is and what is the route to them) they would also have an excellent chance of understanding the feeling of anticipation in the video.

  • $\begingroup$ I this story, they don’t know about us in detail. $\endgroup$
    – JDługosz
    Commented Feb 8, 2017 at 16:37
  • $\begingroup$ @JDługosz: In that case, how can they even expect that their target civilization would have any emotions at all, let alone trying to communicate complex messages as expectation, invitation etc? $\endgroup$ Commented Feb 8, 2017 at 17:03
  • $\begingroup$ That is another question really… the details of emotion might vary, but any organism that controls its environment will have goals and “desires” in some sense. (I don’t want to foreshadow my own Answer just yet.) $\endgroup$
    – JDługosz
    Commented Feb 8, 2017 at 17:12
  • $\begingroup$ If you want to believe that, @JDługosz Only because we humans look at the world in a certain way does not mean it is the objective reality ... $\endgroup$ Commented Feb 8, 2017 at 19:15

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .