Humans have finally made contact with aliens! We've just received a signal from a civilization somewhere in the Orion Nebula. It contains a message from their civilization, talking a bit about their culture, and asking for a response from anyone who receives the message. It's a bit like the Arecibo Message.

This is great, but the message was sent over 1300 years ago, and it will take 1300 years to send a reply. In addition, the signal itself is pretty terrible. I didn't mention that it took a team of cryptographers two years to decipher it.

We'd love to send a reply and initiate some sort of cultural dialogue/exchange between us and the aliens - assuming they still exist. But when it takes nearly 2700 years to have a call and response, communication is difficult.

I'm asking whether or not it will ever be possible for two civilizations to communicate with each other and exchange cultural ideas with one another, given how far away they are. Assume that the language issue can be solved without too much difficulty, and each civilization survives without too much fundamental change for long periods of time (10,000 years, at the least) - not likely, but necessary.

So, is this possible?

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    $\begingroup$ There was a 365 Tomorrows story about this once. I can't find it now, but the aliens and humans would have concerts together even though they weren't able to communicate nearly anything else. Of course, the aliens' music was light-based and humans needed significant shielding in order to witness it and survive, but hey. Edit: ha, misread the question. $\endgroup$ – Draco18s no longer trusts SE Jan 18 '16 at 18:10
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    $\begingroup$ @Draco18s how did you read it? $\endgroup$ – PyRulez Jan 19 '16 at 2:45
  • $\begingroup$ Is there any possibility to transmit Information in FTL? Like, by manipulating gravity (which cascades instantly), this would allow an instant communication, without the ability to meet each other. $\endgroup$ – Bounce Jan 19 '16 at 13:23
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    $\begingroup$ @Bounce According to General Relativity, gravity propagates at the speed of light, not instantly. $\endgroup$ – Scott Downey Jan 19 '16 at 15:16
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    $\begingroup$ @PyRulez I read it as "if we ever meet" and mentally inserted some sort of language barrier, rather than distance barrier. It cued mental recall of the 365 Story that despite having almost no ability to communicate with this one alien race they still were able to share and enjoy music with each other. I went off looking for that story before reading the actual question. :D $\endgroup$ – Draco18s no longer trusts SE Jan 19 '16 at 15:18

Yes, and no. Mostly no. a 1300 year half duplex conversation would be intolerable for any species not similar to the Thek.

The most useful would be to start a constant stream of communication back to them. Like a tv station. Just keep broadcasting. With any luck, after 2600 years (from the first message sent) if the civilization that started the call, still existed, heard the message, and were willing to respond, then they could start sending out a constant stream back.

Doing a constant stream of data, would allow for an exchange of cultures and ideas, but they would always be about 1300 years behind actual developments.

EDT: Another thought, for us to actually receive the 'message' is chance, as over the last 10,000 years of human history, only the last 50-60 would we have had a chance to even catch it. and Earth is how old? and there has only been a blink of time it could be caught? I suspect that they would have to send out a 1000 year or 10,000 year message to have any chance of catching anyone. So we'd be learning about 1300 years behind them. and we could start by sending out our own stream, which they would get in another 1300 years...

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    $\begingroup$ A great conversation for space ents who "takkkkeeee aaa lllloonnnngggg ttttimmmmmeeee..." $\endgroup$ – Prinsig Jan 19 '16 at 9:46
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    $\begingroup$ 2601 years later the message comes back "unsubscribe". $\endgroup$ – Steve Jessop Jan 19 '16 at 16:15
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    $\begingroup$ Something relevant - en.wikipedia.org/wiki/My_Son,_the_Physicist $\endgroup$ – user96551 Jan 19 '16 at 19:31

What if short lived lifetimes of ~100 years are abnormal in the galaxy?
Alien species could be immortal, or hibernate for centuries, or be post singularity, or something similar so that 1300 years isn't a big deal to them.

We'd have a hard time of it, unless we somehow came up with a work around for the whole death thing.
An AI could potentially do it, in that it could act as record keeper and coordinator of the message.

There wouldn't be much of a point to an exchange, except as a series of data dumps. Kind of a "well, if something happens to us, at least you'll know who we were."

The biggest impact that this would really have is the realization that there is someone out there at all.

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    $\begingroup$ Given our current rate of increasing lifespan, it's only a matter of time until we've solved that pesky death problem too. $\endgroup$ – corsiKa Jan 18 '16 at 20:35
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    $\begingroup$ The current increasing of lifespan is really about keeping old people alive for longer: it doesn't tackle aging as such. However, i do think that genetic research is likely to "cure" aging within the next 100 years. $\endgroup$ – Max Williams Jan 19 '16 at 12:05
  • $\begingroup$ @corsiKa: Nature is almost never linear, though. $\endgroup$ – phresnel Jan 19 '16 at 13:32
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    $\begingroup$ @phresnel They said Moore's law would have diminishing returns too, 50 years later it's still going strong. $\endgroup$ – corsiKa Jan 19 '16 at 18:26
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    $\begingroup$ @corsiKa: Yes, not because it's natural, but driven exactly to that by research and economy. There were/are times where Moore's Law could have been beaten, and times in which not. Moore's law and the keeping-up of its validity is human driven, not driven by nature. It would be strange otherwise, if you think about it. See also en.wikipedia.org/wiki/… . Likewise, life spans have always increased and decreased. And even if we became highlanders, with growing age grows the probability to have a deadly accident/illness. $\endgroup$ – phresnel Jan 20 '16 at 9:24

Real-time communication should not be crucial for the cultural exchange; there were cases when one culture was heavily influenced by an extinct culture (Renaissance grew from a rediscovered Greek philosophy, some modern cults are based on paganism, something like that).
Of course, that means that the aliens should have sent enough information to spark people's imagination, but it still seems possible.

  • $\begingroup$ If both species are using radio signals to communicate over light years apart they will never make any progress.You cant make barriers and laws to solve the unknown.It will only lengthen your solution.You ever get a great idea and think your smart for coming up with it? Maybe that idea was not even yours, Maybe you already made communication with a being from a 1000 galaxies away and didn't even realize it.Thoughts travel at light speed, That's why when you fall asleep for a minute yet had this wonderful dream that lasted so long and detailed but it all took place in a second or two. $\endgroup$ – user5434678 Jan 19 '16 at 0:41
  • $\begingroup$ @TheVoid It's very difficult to understand what you're saying or how it relates to this answer. $\endgroup$ – JBentley Jan 20 '16 at 20:11

You would exchange cultural ideas of the species as a whole rather than a snapshot of any particular time or civilization.

With over a millennium of transit time for messages, attempting to hold a two-way conversation will have very little real usefulness. Even if you manage to establish a protocol of sending messages once weekly, it would take a thousand years to experience the delayed sense of a back-and-forth conversation. In the meantime, neither planet can know for certain that the other still exists.

But even in this framework, so much can be shared. The foundational idea that we’re not alone has enormous cultural impact. Information about our stellar neighborhoods could be shared and would be reliable on such a long timescale. Detailed information about the biological makeup of each main species and other lesser species could be transmitted. The wealth of data in those points alone would be tremendously useful to both new neighbors.

When contemplating a transmission of our cultural values, however, human history and some degree of relativism is necessary. For us to describe only our modern snapshot of cultural and societal views would be useless over such long timescales. Furthermore, how do we attempt to describe a collective human culture when we have so many distinct ones? Surely each one of them provides its own special insight into our species. Similarly, what good is even a comprehensive snapshot without context? The full history of our species, its varying civilizations, and the evolution of culture helps to paint a less time-sensitive view of who we are and why.

So it seems that a meaningful culture exchange is possible, but shouldn’t be approached as a discussion. It’s quite literally an exchange of histories and information, as much as can possibly be transmitted to paint a comprehensive picture of who we were for the astronomical instant we existed.


1300 years ago would put us in 715AD, somewhere in the middle of the European Dark Ages. Languages would be incomprehensible to us, technology very primitive and health and hygiene shocking to contemplate for a person arriving from 2015.

Going the other way, we would arrive in the year 3315. Languages wold have changed beyond all recognition, and assuming a linear rate of development, we would simply not be able to recognize most technology of the day. IF the human race had passed through the singularity, we might not recognize anything.

So the idea of "cultural exchange" would be meaningless in any real terms. We are receiving a snapshot from the distant past, and anything we send today will be received by what in the most likely scenario be a totally different culture than the one which sent the message. To give you an idea of the time scale involved in a round trip, if a message was sent from Classical Greece (585 BC), received in the dark ages (715 AD) and the reply sent we would just be getting this now.

Given the drastic changes in cultures between those eras, it is possible that the very memory of a message sent to the stars will be a dimly remembered legend if/when a return message arrives after a 2600 year round trip.

We can certainly learn from the message, and any putative recipients of our message to the aliens might learn a thing or two about us, but this will be more like visiting a poorly curated and catalogued museum exhibition (there will be lots of things we don't understand about the message, and we will never have a chance to ask follow up questions and receive the answer in any meaningful time frame).


Yes. Meaningful exchange of cultural ideas does not require two-way communication or timely replies.

After all, archaeologists get very meaningful cultural information by studying our own past cultures, without any hope of their ever receiving anything from us, since they don't seem to exist any more.

I'd say that as soon as we receive a message that we recognize as a message, we've received very interesting alien cultural information, even as soon as knowing there is an alien intelligence out there, who chose this method to send some information out. It's all meaningful cultural data.

Cultures exchange ideas over millennia anyway, even just on Earth. We're still struggling with our own cultural ideas that are thousands and thousands of years old. Sometimes we forget or pretend otherwise, such as with modernist reductionism or modern religions which pretend they aren't remixes of ideas taken from other ancient religions.)

The 1300-year delay would make responses take many human generations, and probably one side would be first to send, and would likely have 1300 years more head start sending, and delay before first reception of anything. Or more than 1300 years, since the receiving people might not notice for years or centuries, and/or not decode for years or centuries, and/or not send anything back for years or centuries, and the original senders might also have delays noticing and decoding.

If by "exchange" you mean we're both sending and receiving, then of course you're right that it's more interesting when we're sending something back, more interesting once they've received something (2600+ years after they sent something), and even more interesting 3900+ and 5200+ years further on, when we're responding to each other, and the delay is crazy long, but it's all meaningful and interesting. I guarantee that entire professions would be dedicated to studying what they send and deciding what to send back, as soon as we receive the first transmission.

In fact, we already started, at first unconsciously when we started broadcasting radio and TV, and then later when we started sending and listening for alien intelligence.


A sufficient advanced civilization could also send to others a way to build some sort of Artificial Intelligence mimics original one. For example for a robotic, AI or post-singularity civilizations this could be similar to mind uploading, but no from real world into some virtual reality but to another part of the galaxy.

With similar point in mind a communication between two species could be complete and game-changing for receiving civilization. Imagine impact on earth if first discovered message could be decrypt (I think it's possible to decrypt almost anything, but is my point of view, maybe using something related to physics, like structure of hydrogen or water) and become an IA able to self-thought and communication abilities.

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    $\begingroup$ Welcome to Worldbuilding! Thank you for your answer. As it is now, your answer is very hard to understand. Could you please read it, and try to reword it? For example: did you mean AI instead of IA? what does "dump" into communication or if first discovered message could [...] become an IA able to self-thought and communication abilities mean $\endgroup$ – T3 H40 - reinstate Monica Jan 19 '16 at 15:54
  • $\begingroup$ @T3H40 The spelling and grammar might be a little off (non-native English speaker perhaps?) but I understood the answer perfectly well. He's saying the communication could encode a way for us to assemble a functioning specimen of their race that we could then communicate with in person. $\endgroup$ – JBentley Jan 20 '16 at 20:18
  • $\begingroup$ @JBentley it might be my fault (I am neither a native speaker), but I really had trouble understanding (some parts of) the answer. If you understand it, would you suggest an edit and fix the grammar? I tried to, but gave up because I did not want to accidentally destroy the original statement $\endgroup$ – T3 H40 - reinstate Monica Jan 20 '16 at 20:29
  • $\begingroup$ @JBentley it's now more clear for you ? $\endgroup$ – Vokail Jan 25 '16 at 7:36

A light pulse using the morse code method.Might be a little more private of a message...And a more controlled projection.Just gotta hope they used morse code at one time.Plus it might be a more private call.That's why everyone dont have the same phone number and use a caller id device before answering....progress?

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    $\begingroup$ This kind of misses the point of the question. You've still got the issue of waiting 1300 years for a response. $\endgroup$ – HDE 226868 Jan 19 '16 at 1:07
  • $\begingroup$ It would only make sense to predict your race 1300 years ahead of time and more like guess of what things are like and technologies are available so when the other planet receives the message it will seem like your talking in real time.That's the only way too delay 1300 years. $\endgroup$ – user5434678 Jan 19 '16 at 1:40
  • $\begingroup$ The question just says "signal", not how it was transmitted. If they specifically wanted to talk to us, they might have used a laser, and it would almost certainly be digitally encoded, not analog. I assume you didn't literally mean Morse Code ;-) $\endgroup$ – Spike0xff Jan 19 '16 at 3:43
  • $\begingroup$ Ok it seems like these two species are identical in technology as well consciousness due to the fact they use the same communication system.Neither would gain a significant leap in knowledge or technology as well as ancient info, they are both learning at the same rate.So info outdated by 1300 years would be meaningless.Humans have records and a large understanding of what occurred 1300 years ago.Cultural ideas could not be gained.If the species were 1300 years apart in consciousness or evolution, info between them could be beneficial, especially for the younger species. $\endgroup$ – user5434678 Jan 19 '16 at 4:47

Recall that the two end points are not stationary. Earth revolves around the sun, the sun revolves around a rough center point of the galaxy, and the galaxy itself is moving... and so is the Orion Nebula, your proposed location for the aliens.

Add to this that it is impossible to properly attenuate a signal over such a vast distance (Even a laser pointer becomes spread out over the distance from Earth to the Moon, and not entirely due to atmospheric refraction), and you end up with a rather unpleasant situation:

We must have been incredibly lucky to detect, attenuate, and decipher the signal. Working with this as a given from your question, we still have to determine where the signal came from - and quite precisely, and where that point of origin will be in relation to where we will be, 1300 years from now.

Actually, that's not even accurate, since we'll be moving at different relative velocities through the galaxy, so what is 1300 light years now, may be 1350 light years then. That 50 year difference could result in us pointing the signal a half a degree too far to the left, and the intended recipient never hearing a reply.

So we must calculate where they will be as a function of time compared to where we will be as a function of time, factor the speed of our signal, and plot a correct intercept. And then find a way to send our own signal with a properly tight beam that there's sufficient signal left when it gets there.

Let's say there was a drift of 50 years, so it took 1300 for them to send their signal, 1350 for us to send ours, their next might be 1400 years, and so on. Granted, it COULD go the other way, but...I feel like even the technical aspects of communicating over such vast distances are nontrivial, let alone the time aspects.


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