i'm sure this has been suggested before, but i don't really know where this stuff is discussed, so i'll post my idea here anyways.

first we need a packet protocol. each "message packet" is padded on each side by a very long string of zeros, so that there is no confusion about packet boundaries. each "message packet" starts out with an ascending sequence of all symbols in our alphabet (i.e. if we are transmitting in binary, it starts out with a "1"), which is not part of the message content. we will assuming that the receiver can figure this out.

next, i can think of two alternate paths to follow, the theorem path and the simulation path.

simulation path

We need to setup a language to transmit computations in. we will pick one of the smallest known Turing machines. To make it clear what's happening, we transmit a sequence of programs for this machine (each one in a different packet) that do trivial but "orderly" things, for instance,

(1) a program that halts immediately (2) a program that writes a "1" and then halts immediately (3) a program that writes "11" and then halts immediately (4) a program that writes "111" and then halts immediately (5) a program that writes an empty packet (a bunch of zeros, then an ascending sequence of symbols, then a bunch of zeros) and then halts immediately (6) a program that writes nothing, and goes into an infinite loop (7) a program that does unary addition (8) a program that does unary subtraction (9) a program that does unary multiplication (10) a program that does unary division (11) a program that does unary exponentiation (12) a program that does unary square roots (13) a program that does unary n-th roots (14-20) programs to do base n (where n = # of symbols in our packet alphabet) arithmetic operations

We assume that the receiver will think of this strategy, and will try running whatever we transmit as a program on each of the small Turing machines, noticing if anything "interesting" results.

Next, we need to setup a cartesian spatial metaphor.

(21) A program which accepts two inputs, the beginning and ending of a 1D line segment, and draws the line segment onto the tape (22) A program which accepts two (4) inputs, the beginning and ending of a 2D line segment, and draws the line segment onto the tape, using a coding that sets aside part of the tape as a square, cartesian representation of a 2D space (23) A program which accepts one input, a length, and draws an equilateral triangle onto the tape, centered in the middle of the space, and using the input length as the side length (24) A program which accepts one input, a length, and draws a square onto the tape, using the input length as the side length (25) A program which accepts one input, a length, and draws a circle onto the tape, using the input length as the radius

Now we need to get across the idea of simulation.

(26) Send a program which is a pretty good simulator of physics at the quantum level, as we understand it, with empty space as the initial condition (27) Send a program which is a pretty good simulator of physics at the quantum level, as we understand it, with one particle as the initial condition (28) Send a program which is a pretty good simulator of physics at the quantum level, as we understand it, with two particles as the initial condition (29) Send a program which is a pretty good simulator of physics at the quantum level, as we understand it, with three particles as the initial condition (30) A few more, with more interesting initial conditions (two-slit experiment, anyone?) (??) Quantum simulation with a hydrogen atom as initial condition ... (??) Quantum simulation with an oxygen atom as initial condition (??) Quantum simulation with a hydrogen molecule (H_2) as initial condition ... (??) Quantum simulation with an oxygen molecule (O_2) as initial condition (??) Quantum simulation with a water molecule as initial condition (??) Quantum simulation with a separate hydrogen and oxygen atoms as initial condition, which form into a water molecule as simulation goes on

Now, it would take to long to send/compute quantum-level simulations of bigger things, so we have to get across the idea of higher-level simulations.

(??) A chemistry-level simulator program. Redo each of the previous simulation conditions which are high-enough level to be replicated in the chemistry simulation (i.e. probably not the individual quantum particles, but probably all of the things with atoms). For each one, first retransmit the packet with the quantum simulator for that condition, then transmit a new packet with the chemistry simulator of the same initial condition.

At this point we have the language to start giving our biology, if we so choose. But we also have the spatial simulation metaphor down, and so we can use the simulation language to build a language to communicate animations, that is, concatenations of frames of cartesian pictures of discrete instants. this can then be used for other things.

also, we can start sending rasters of children's books as soon as we get the raster metaphor down from the 2-D geometric shapes. if they are sufficiently similar to us, that may be enough for them to decipher a human language.

i didn't write this but i think the "if you are predators" bit is a great idea because it may get across the idea of humor even to aliens:

" hello out there;

just sending you a message to say

if you are friendly and have the

ability to travel the long distances

necessary to visit us, DON'T!

we can't get along with ourselves

so doubt we will with you.


on the other hand, if you are predators

regard this message as a crank call with

a phoney address "

summary of some other messages i liked from that site (i think the site is assuming that we already have a common language):

audio of typical sounds from Earth:

some of the sounds had a lot of high-frequency chirps (like "sneakers" and "bracelets"), which i dont think is a good idea b/c the receiver may think they encode a digital message

there were also some typical beautiful photos, some with artifacts (like the golden gate bridge). i think these are a good idea too. the golden gate bridge pic is good. other suggested pics:

however, by sending sounds and photos (assuming they are not already able to observe the Earth in detail), we are giving them military intelligence, so we may not want to do that.

we may also want to send "famously great" music that has remained popular for decades or centuries.

many messages said, "help!" or asked the receiver to come and help us or come and save us from ourselves. i don't think this is appropriate b/c it may be read as an invitation for the receiver to use force to take control, which is probably not the wish of the majority here.

other messages said things like "please come, we are peaceful!" or "my home is your home". i think the first of these is a lie (we would LIKE to be peaceful, but we aren't), and the second is an offer that the majority may not agree with (it essentially claims that we are not a species that uses the concept of territor, which is not the case; if non-territorial aliens landed and began building structures without asking permission, i think many humans would flip out, therefore this offer should not be made).

other messages contained stuff like, "go away for 1000 years, we aren't ready for you yet", which again, i'm not sure the majority would agree with.

other messages contained stuff like, "warning: we are violent, we may attempt to kill you", which i think is partly a good idea, out of honesty and to prevent diplomatic troubles, but i think you have to watch out because a mistranslation may make this seem like a threat.

other messages contained stuff like, "we wish for peace but have not yet acheived it amongst ourselves", which i think is a better idea; by not using the words for violence and war, but only their opposites, the chance of mistranslation is lessened, and also this makes it clear that the violence is not directed at the receiver, i.e. that we are not threatening. of course, the receiver can infer that if we are violent towards each other, we may be violent towards outsiders, so the desired information is passed along, with less chance of the message being interpreted as an intentional threat.

some messages professed a faith in God; mb the majority agree with this, but i don't, so i'd prefer it not be sent.

other messages had poems, which i think is a good idea, provided that a declarative statement come before it warning that the following block of text is nonsense (has no truth value, and is not a speech act).

other messages specifically focus blame on certain problems (i.e. environmental degradation) or institutions (governments) for what is wrong with our world. it seems to me that such things would not gather widespread consensus and so should not be sent. also, asking for advice in such a focused way may be seen as a rude demand (why do you demand knowledge of ecological engineering when you have not offered us anything?), or may engender a naive reply (we understand that your atmosphere is undergoing undesirable chemical changes? we suggest that you reduce somewhat those industrial activities which generate gaseous emissions -- of course, keeping in mind the economic and political tradeoffs.) (another example of a naive reply: we understand that you are driving other lifeforms on your planet to extinction and are unhappy about this. why then do you not refrain from driving them to extinction? why do you ask us to help you not do something which is voluntary? are you under compulsion from a higher power which you wish to escape? does your cognitive apparatus contain a known programming bug, but lack the access rights to patch yourself?) (the point of both naive replies is that, if the speaker were in control of the human race, they could easily stop the activites that they are complaining to the aliens about -- the real question is either something like, 'the speaker thinks this activity is an error, but many humans disagree; do you agree? how can i convince the other humans/how can we change our sociopolitical institutions to avoid this activity?', or something like, 'this activity generates large benefits but also large costs -- what decision-making procedure should be used to strike a balance?' )

i like the idea of asking for advice, though.

other ones i like:

"This is Earth speaking. We would like to know you, please reply with some message.

Peace. "

"Let's be friends and share knowledge."

"I would not send one message, they could never figure out what it means. Send as much as we can: whole books, the entire dictionary, the bible, the NASA database, everything. "

"We value logic, emotion, respect for life, truth and strength. "

-- i like this one because it is true, it communicates characteristics of humans which may not be constant across all intelligent life, and it is important for aliens to know about these characteristics if they are to interact successfully with us. also, in case the aliens cannot observe us in detail yet, it does not give away much useful military intelligence (or at least, everything that it does give away has to be, because an understanding of these human characteristics are very important in order to maximize the chance of peaceful negotiations succeeding)

pi encoded: yes

"Down here we are all confused." -- gives a little too much information ("down here" implies gravity bound -- how about just "all humans are confused"?) : gives a LOT of military intelligence, but may be good anyhow


"Live long and prosper" -- yes

"Approach us with caution. New things may frighten us and in becoming frightened, we may attack if we feel that is the safest immediate reaction. I send this warning because in the end, We would like to be friends. We will need your help to achieve this." -- yes -- except as i said the word "attack" should not appear. i think the word "frighten" is fine, as long as it is clear we are the ones who are frightened. on the site, this one ended with "Also, don't kidnap us and poke us. We hate that.", which of course should be omitted

"Despite the news, despite events and things in our past, there is still idealism. You will see it in some of our fiction: little glimpses into the way we wish things were, the way we wish we could be, glimmers of idealism and hope that withstand all the negativity in the universe. If you see us as we are today, then we still wish to be better people. If we are gone or changed, then know that there was a time when we wished to be better people and we shared that dream with each other in the hope that we could some day make it come true. "

"Greetings,whoever and whereever you are.You receiving this means we are not alone-thank you for that alone.We are peaceloving beings but emotional and I personally think,that is due to a couple of unanswered questions-may be you do have the same questions or an answer already?Why are we here?How many of us are there?Is there a meaning to all this? Again:if you read this, we and you are not alone!Please reply! "

i encourage asking deep questions (presuming the common language might support it)

another one mentioned "Love, Truth and Beauty, Trust, Harmony", which are good

"The dominant species on our planet has been in an almost continuous state of war for the past 2,000 years principally over disputes over the identity and interpretation of the creator of the universe. I believe that we will end up extinguishing our species and countless others on this planet as a result of this dispute which I believe is pointless anyway for, what does it matter who or what created our species. My question is this: has your species experienced the same dispute? If you have survived it, how did you do so? How was the dispute resolved and can it be proved, once and for all time, whether or not there is an original creator of the universe, what is his/her/its identity and does he/she/it wish to be blindly and continuously worshipped and spoken to of drivel?" -- maybe, although "war" should be replaced with a vauger statement, less this be read as a threat