Friday, August 13, 2004
New Scientist: Alien Contact
The current (Aug 7-13, 2004) issue of New Scientist magazine contains an article by Paul Davies ("Do We Have to Spell It Out?") pondering how aliens might contact us by means other than a signal in the electromagnetic realm, and having been interested in the related subject of how we could most successfully create a message that could be interpreted by aliens, and, consequently, what kinds of message structures aliens might use to communicate with us, I had a few thoughts on what Davies had to say.
Davies essentially says that if aliens were sufficiently advanced from us, which, at this point, seems possible should they exist at all, their method of sending a message to us might be to embed a message on the planet, rather than to beam a message to us continually from afar. Specifically, Davies suggests that the message might be hidden in the very basis of life itself: DNA.
My first concern with this is the enormous distance that likely lies between us and the nearest alien life. I read yesterday in a book I'm reading entitled Time Out for Tomorrow that, by the author's calculations, if life were distributed evenly across our galaxy at the rate that the author presumed it to exist (the question of the probabilistic evidence for life is fodder for future entries here), there would be one planet with intelligent life every 1000 light years. To me, that's a very long way to travel at sub-light speeds, and worse if you assume that the aliens that send off these virus-laden probes with their message to the future intelligent beings, are not our nearest neighbor.
But Davies starts the article by indicating that these intelligent life forms may be hundreds of millions of years more advanced than us (which brings about all sorts of other discussions that I'll table for now), so it is presumed that enough time for such a probe to reach us from where ever they are has passed, and/or that they have developed technology to travel very near, at, or beyond the speed of light.
Davies suggests that aliens might choose to embed their message in DNA as it (or certain parts of it) are self correcting, helping to ensure its continued existence for hundreds of millions of years or more. This method also, by the way, has the benefit of being right under our noses all of the time, making it more likely to be found, and has the further benefit of being a "time release", or, more accurately, and "intelligence release" capsule whereby only sufficiently advanced beings would be able to discover and decode it.
His choice is to put it in specific sections of so-called "Junk DNA", certain specific portions of which are apparently very prone to being conserved as is. Apparently these specific sections have been wholly removed from mice with no ill effect, making them prime candidates for containing a message. Further, Davies indicates that theses sections are quite large meaning that extensive information could be passed along from the aliens to us in them.
I wonder, at this point, if it is fair to assume that all life (should it exist) anywhere in the galaxy, is based on the same procession of intertwining nucleotides that is the basis for our life? Is it safe to assume that DNA would evolve at all on another planet as a requirement for life, or could other functionally equivalent mechanisms substitute for it, and perhaps be more common. The assumption that aliens would send off probes full of message-carrying virus in the direction of any planet potentially capable of evolving life with DNA seems like a bit of a stretch, though this may reflect my better understanding of engineering (where functionally equivalent processes are often substituted for each other) than of biology.
More likely, frankly, would be that aliens sent the germ of life anywhere they thought it would survive; an outcome we will have to consider deeply should a message be discovered in our DNA (should that fact not be explicitly stated). For the time, however, I content myself to believe that current evidence is in the ballpark enough to explain the evolution of life on this planet.
Nonetheless, if it is indeed true that there are large strings of seemingly useless junk DNA, it would beg the question of why. While evolution is not a super efficient mechanism producing entities with no inefficiencies, large amounts of junk DNA stored in every cell on earth does seem like a huge waste of resources if it is to not serve any purpose.
Assuming for the moment that there is a message hidden in our bodies, long strings of the same nucleotides are definitely, as Davies suggests, excellent message markers. There would have to be a sufficient amount of them that the odds of that string appearing at random would be vanishingly small. Making this more difficult to spot, I imagine, are mutations that Davies seems to indicate happen even in this protected section of our genes. A stray mutation every few dozen nucleotides may make any long string of single nucleotides difficult to spot. Similarly with prime numbers, another mechanism of tagging a message that Davies relates.
More difficult still would be the method Davies relates from the Carl Sagan novel Contact. It's been a long time since I've read that book (which I enjoyed immensely), but it seems like a long stretch to assume that aliens would be, in short order, able to get us to sort the data of their message into a two-dimensional array from which the picture of a circle would appear without providing us enough information to conclude, already, that we were receiving a message from another sentient being. And, again, mutations would make this all the more difficult. Without such guidance, it seems like guessing the right array size might take a very long time indeed.
I wonder if information theory, or something similar, has a method of approximating the amount of potential information in a string of characters to help determine the likelihood of there being a message in something. I'm guessing there probably is, and that people like Davies have exactly that in mind when they go trolling for messages in this kind of data. If anyone has a link to a good summary of this kind of process, let me know.
I think the idea of a message in our DNA has a certain kind of elegance to it, and hope that someone decides to test it out with a reasonable method at some point. I don't, however, hold out much hope. Assuming that there are ETs out there (which, given some recent articles I've read about the fact that the earth may be more unique that we originally thought, seems less likely, which is not to say unlikely), and that they were interested in sending us a message and were sufficiently advanced in both time and technology to do so, doing it in our DNA just doesn't ring the right chord for me.
I would probably have to side with Clarke and put a message on the moon of some durable advanced alloy, that would be found in a straightforward manner (radiation searching, for example) when the target species' technology had sufficiently advanced. Better yet, something that was a beacon that millions of planets could see without having to send something to every planet that could carry some form of life. Maybe a rotating neutron star or the like. Of course if the most obvious places might require fiddling with the very nature of the universe in such a way as to change things we currently consider constants...perhaps something sufficiently down in the digits of pi...