OK, Say You're an Extraterrestrial ...

[TromboneAl]

In a subplot of my book, a highly advanced civilization has a probe that travels around the galaxy, visiting solar systems. When it detects signals from a planet, it heads over to it, and sends it a message.

The message it wants to send is: "There are many civilizations in the galaxy. Send me signals, and I will relay them at faster than light speeds."

First do you see any problems with that scenario? The advantage over just sending out signals is that primitive civilizations like ours would have trouble detecting them, and only light-speed waves can be sent out. But if a probe gets in your face, it would be hard to miss it, and a dialogue could be set up in real time.

Second, how would you design a message that could be decoded by a civilization with nothing in common with the sending species? I've looked at the arecibo message, and not been impressed, same with the Voyager plaque. I haven't found much info on how a message might look. Links?

My thought would be to have, like the arecibo message, a series of bitmapped images--essentially a movie. But it could have a much higher resolution. I don't see a problem with getting that basic message across.

Thanks for helping me brainstorm.

 

[REWahoo]

Rule #1: This is science fiction.

The message it wants to send is: "There are many civilizations in the galaxy. Send me signals, and I will relay them at faster than light speeds."

First do you see any problems with that scenario?

No, see rule #1

Second, how would you design a message that could be decoded by a civilization with nothing in common with the sending species? I've looked at the arecibo message, and not been impressed, same with the plaque. I haven't found much info on how a message might look. Links?

My thought would be to have, like the arecibo message, a series of bitmapped images--essentially a movie. But it could have a much higher resolution. I don't see a problem with getting that basic message across.

No, see rule #1.

 

[dallas27]

No problem with the first, just respond in the same rf it detects.

The second, research the voyager space probe, the best minds in the world tackled this problem and put the messages on that probe in various ways. Should give you inspiration.

I want footnote credit and a b-part in the film adaptation!




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[Nemo2]

If the probe can send signals at light speed it will of course have a built in braking system that slows the signals just prior to 'impact'.

 

[TromboneAl]

The second, research the voyager space probe, the best minds in the world tackled this problem and put the messages on that probe in various ways. Should give you inspiration.

Yes, that plaque is interesting. I take it back about not being impressed with it.

All it says is "This is where we live, and this is what we look like," but it does that very well. The distances and directions to the pulsars is genius. I was thinking "Who would care what we look like," but I guess that would be interesting to some other civilization.

 

[growing_older]

Since your incoming probe can relay signals at faster than lightspeed to any number of highly advanced civilizations, why not fall back on the simpler assumption that they analyze us. We're sending all kinds of signals that can be decoded and analyzed by sufficiently advanced intelligences. Let them "learn" a few prominent Earth languages and they can just talk to us without requiring that we decode their primer. They can even transmit on the same frequencies they see us using.

 

[brewer12345]

How did I know that a thread about extraterrestrials would include lots about a probe?

 

[Walt34]

How did I know that a thread about extraterrestrials would include lots about a probe?

I'm afraid to ask - what kind of probe?

 

[Animorph]

Since your incoming probe can relay signals at faster than lightspeed to any number of highly advanced civilizations, why not fall back on the simpler assumption that they analyze us. We're sending all kinds of signals that can be decoded and analyzed by sufficiently advanced intelligences. Let them "learn" a few prominent Earth languages and they can just talk to us without requiring that we decode their primer. They can even transmit on the same frequencies they see us using.

That's a great answer!

One of my favorite contact methods was a 2D picture/video with a prime number of pixels horizontally and vertically and a clear framing signal. Fairly easy to decode. Pictures easily avoid the language problem and can contain a lot of info.

 

[photoguy]

What's the goal of the communication? Curiosity? Or something more sinister (as per Hawkins suggestion).


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[samclem]

Re: "What signal to send"--it's probably worth looking at how the folks doing SETI now are hoping to sort the wheat from the chaff in all the signals they intercept. Just make your signal from the spacecraft meet the requirements of the SETI filters (and this gives you a chance to mention how SETI does this right now in your book).

Regarding the premise: Isaac Asimov had a good "science fact" story that is perhaps germane, "The Rocketing Dutchmen" IIRC. He didn't put much stock in reports of extraterrestrials making contact with us--they are advanced enough to physically cross light years, but not smart enough to either 1) avoid detection if they want to or 2) make contact in an intelligent way (not with a bunch of drunk yokels in a cornfield)? Seems a bit odd. Along this line, I'd go with Growing Older's idea--and the probe communicates directly with the folks on earth who they want to speak with, not the folks at SETI.

Knowing that societies would probably be extensively altered by an external contact, the more advanced "outreach" society, especially if able to actually travel to other civilizations, would probably study the society for quite a while before deciding to alter the "target" civilization with any direct contact. Star Trek "Prime Directive" and all that . . .

 

[samclem]

What's the goal of the communication? Curiosity? Or something more sinister (as per Hawkins suggestion).

 

[MooreBonds]

Second, how would you design a message that could be decoded by a civilization with nothing in common with the sending species? I've looked at the arecibo message, and not been impressed, same with the Voyager plaque. I haven't found much info on how a message might look. Links?

My thought would be to have, like the arecibo message, a series of bitmapped images--essentially a movie. But it could have a much higher resolution. I don't see a problem with getting that basic message across.

Thanks for helping me brainstorm.

I like the 'movie' idea to communicate - either an actual digital movie, or series of pictures. Most advance species will likely be using some form of the visible band of the EM spectrum for the bulk of their communication, since that's what probably all star systems have a predominance of.

Regarding the Voyager plaque - you have to remember, this was 1977. The cost per pound to launch something into deep space was (and still is) phenomenally high. Not to mention it has to withstand all of that nasty interstellar radiation. Oh, and temperatures down to, what, like 10 Kelvin? (average deep space temp is something on the order of 3 Kelvin, if memory serves me correctly). And being able to not degrade over, say, a billion years.

 

[TromboneAl]

Since your incoming probe can relay signals at faster than lightspeed to any number of highly advanced civilizations, why not fall back on the simpler assumption that they analyze us. We're sending all kinds of signals that can be decoded and analyzed by sufficiently advanced intelligences. Let them "learn" a few prominent Earth languages and they can just talk to us without requiring that we decode their primer. They can even transmit on the same frequencies they see us using.

Yes, very good point. Perhaps the civilization is impatient. Or better, they only need a few minutes of gathering and relaying all of our signals from earth before they can decode and understand our language.

OTOH, I'd prefer to deal with this issue of early communication between to completely different civilizations.

Perhaps there's a limit on the bandwidth of the faster than light transmissions.

Good points that need to be dealt with, thanks.

 

[TromboneAl]

One of my favorite contact methods was a 2D picture/video with a prime number of pixels horizontally and vertically and a clear framing signal. Fairly easy to decode. Pictures easily avoid the language problem and can contain a lot of info.

That's my plan at this point. A nice high-res B&W movie, say 1024 by 1024 pixels.

It starts with an image of the probe, showing it next to a planet. The planet shows lights, suggesting a civilization. Then the image zooms out to show the rest of the galaxy, and zooms into other planets that have similar lights.

Next, back to an image of the probe and a planet, showing slow (light-speed) signals between the two. Then it zooms out again, and should faster signals.

But here's a question: Why do the pixel width and height have to be prime numbers? I know Sagan did that, but I'm not sure it's necessary. If the first frame is a square of rectangles along the outer borders, I think that might clue in the receiving civilization.

How would it help if the image were 1009 x 1009?

 

[growing_older]

But here's a question: Why do the pixel width and height have to be prime numbers?

Not strictly necessary. In fact all the frame sizes for all the video systems commonly in use have never had prime width and height pixel counts. The notion made an interesting story point and supposedly made it easier to figure out when a frame started and ended, but the receiving side would still need to figure out it was a series of video frames and guess the width and height. There are plenty of other ways to provide suitable clues, such as your suggestion of some early frames containing images showing the borders, or blanking intervals between frames or between rows containing distinctive values. Likewise avoiding the use of image compression or interlaced images probably considerably simplifies the decoding possibilities.

If you wish to stick with visual communication for initial contact, we've been beaming broadcast TV in electromagnetic spectrum for decades. Assuming alien intelligences have detected those signals, they could do the same decoding you suggest and either send back modified signals or send new images using those coding standards. This has been used as a plot device in other stories, but you could stick strictly with video information (maybe use of audio for communication is rare in the cosmos) to give a unique slant on your treatment of it. Or maybe there's some kind of message formatting that is required to make the faster-than-light telegraph work, so we have to communicate in pictures. Sounds intriguing.

 

[TromboneAl]

This is a general purpose probe, not just for us, so it can't use our TV system. Why would have a prime number width or height make it easier to guess--I haven't figured that out.

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[chilkoot]

Just be aware, if you're not already, that Cadl Sagan (probably others too) wrapped a novel around this idea in the eighties. Check out Contact (the novel is pretty excellent; the movie is only not bad).

 

[MooreBonds]

This is a general purpose probe, not just for us, so it can't use our TV system. Why would have a prime number width or height make it easier to guess--I haven't figured that out.

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Assuming an alien life form would have a numbering and mathematical system somewhat close to ours, they would presumably also have the concept of 'prime numbers'. Since prime numbers are sometimes used in mathematical/electronic equations in certain ways, a random signal with information decoded might have information that is based on a prime number being used in the formatting.

Just like code breaking in WW II. They had to assume some sequence of characters to break up sets of words into. I think they often used 4 or 6 letters per segment. If a code breaker saw one giant long string of characters, they might first assume breaking it up into segments of 4 or 6, and go from there.

Likewise, an alien might assume there might be a usage of prime numbers in the signal, and start their initial segmenting using a prime number interval. It's strictly a random guess that an alien civilization would have prime numbers - but might yield more fruit than randomly picking ANY number to base your signal decoding on.

 

[M Paquette]

There have been a number of SF stories that used contact with an interstellar communications network as a significant element. Here are a few of the better known ones.

The Ophiuchi Hotline, John Varley (1977)
One plot element involves a 'contact' mechanism that uses a sort of observation post, and a laser communications line which just misses the inner solar system, so space travel by the locals is required to receive the messages.

Router, Charles Stross, Asimov's Science Fiction (Sept 2002), also as Accelerando, Chapter 5 (2005)
An automated system has installed a local router with faster-than-light connectivity elsewhere. Humanity eventually notices the router and contacts it. Hilarity ensues, including a 419 scam from outer space.

Singularity Sky, Charles Stross, 2003
An automated system designed to open (or re-open) communications with civilizations enters a solar system. Since communications implies exchange of information, potentially profitable, a variety of other commerce-oriented systems, researchers of a sort, and other hangers-on follow in the immediate wake of the telephone repairman to take advantage of new opportunities. Hilarity, and an economic singularity, ensues...

Contact, Carl Sagan (1985)
A message from a star system 25 light years away is received. The message includes a basic communications primer, and ends with plans to construct a very large machine.

 

[NW-Bound]

Contact, Carl Sagan (1985)
A message from a star system 25 light years away is received. The message includes a basic communications primer, and ends with plans to construct a very large machine.

I am not into SciFi, so have not read the book but did see the movie starring Jodie Foster.

 

[growing_older]

Why would have a prime number width or height make it easier to guess--I haven't figured that out.

Suppose you are using a video frame 1024 x 768. That means there are 786,432 elements in each frame. We know they are arranged in 768 rows of 1024 pixels each, but it could have been 1024 rows of 768 pixels or 512 rows of 1536 pixels or 2048 rows of 384 pixels, and so on. Many many possible combinations.

Now of course this isn't necessarily an insurmountable problem and some combinations are much more likely than others. We are unlikely to use superpanaromic choices like 24 rows of 32,768 pixels even if the math makes it possible. Likewise, your suggestion that we send square frames makes is easy to guess any number is the square. If it's a square frame, the prime number of pixels reinforces that it MUST be a square because a 1009 x 1009 frame of 1,018,081 pixels cannot be divided any other way, but even if it were simply 1000 x 1000 the resulting 1,000,000 pixels are easy to see as a square and the most likely choice, even if other possibilities (500 x 2000) do exist.

 

[Totoro]

Brace yourself for a long post

Are you going for 'hard scifi' as in that you need to work within current known science? In that case forget about FTL communication, as it means essentially you are allowing time traveling and break causality ..

So think about how you want the FTL communication setup. What rules does it adhere to? Or do you want to sidestep the issue and not explain it? As a sci-fi reader i prefer stories working within current physics. I don't mind some liberties taken though (e.g. teleportation, FTL, mind reading) as long as you set the rules and remain self-consistent.

The other item you are talking about is the difficulty of establishing a common language. There you have first the issue of the signal carrier (radio waves, quarks, neutrinos, particles?) and then how to encode the language within the signal carrier (frequency modulation, phase-shift keying, amplitude modulation, ..).

After that, you need somehow to convey the rules (grammar) and vocabulary of the language. This issue is well known in formal mathematics. Basically, in order to describe a language you need a language to describe it with. Humans solve this by using the "pointing language" (point at object and name object) to start.

Carl Sagan was mentioned before, his solution in Contact is to use mathematics within a radio signal. This on the assumption that radio is simple and universal enough for multiple species and mathematics (numbers) is a universal construct that all species need to develop. Neither is a given though, but a reasonable assumption.

If I were to design a message I'd start with the carrier using simple on/off signaling using the full spectrum of light that a typical sun uses. This because any mobile species likely has vision, thus will detect this object. I'm disregarding any power constraints here for sending this signal.

Next, how to start interaction. What you want is a response from the listener that shows he understands what you are sending. Prime numbers can be used, the fibonacci sequence too. Any number sequence actually. What might work is leaving out a number in the sequence and listen for the missing number.

As soon as you receive the missing number, you shift to another sequence with another missing number to double check. You might narrow the frequencies as time goes on too.

Now you have a common carrier and (finally) a way to exchange numbers!

How to go from there to actual language I haven't figured out yet.

I do believe simply sending a bitmap is not as easy as you make it to be. How will you know any sent signal is a bitmap? How is it encoded (binary? why?) How many bits per pixel? What color does every bit indicate?

 

[heeyy_joe]

OK, I'll play along.

"I'm an Extraterrestrial".

Now: Call me a taxi.

 

[omysteve]

Haven't read the entire thread. But if you're looking for what appears (from watching episode 1) to be shaping up as a really good sci-fi series check this one out - Extant http://en.wikipedia.org/wiki/Extant_(TV_series)