To Decode Or Not

Written By: ALEX BLAKE

When thinking about the search for extraterrestrial intelligence we often assume that incontrovertible evidence will either come in the form of some short or not so short green humanoid. Or a piece of hardware that will befuddle the minds of our brightest scientists will somehow fall out of the clear blue sky. But, so far, no one has recovered the remains of a Yoda look-alike, let alone a scrap from some Millenium Falcon type spacecraft built a long time ago in a far far away galaxy.

Does this lack of evidence mean that we finally have evidence of a lack of intelligent life throughout the vast reaches of space? Not quite if we are to believe the co-creator of String Field theory, theoretical physicist Michio Kaku.

According to Dr. Kaku in his article ‘The Physics of Extra-Terrestrial Civilizations,’ ( ) there is more to sending messages via the electromagnetic spectrum than meets the sensor. Leaving aside for the moment the limited range of frequencies being scanned or the problem of deep space static when transmitting on a single frequency, there remains the possibility that an alien civilization might have decided on a more efficient system of broadcasting to minimize transmission errors. Such a system, says Dr. Kaku, could “break up the message and smear it out over all frequencies (e.g. via Fourier like transform) and then reassemble the signal only at the other end. In this way, even if certain frequencies are disrupted by static, enough of the message will survive to accurately reassemble the message via error correction routines.”

And therein lies the dilemma. Is it more likely for an advanced civilization to resort to some sophisticated encoding scheme than we would? Probably. Russian astrophysicist Nicolai Kardashev, in a paper published in 1964 in the Journal of Soviet Astronomy, wrote that advanced civilizations can be classified according to three groups: Type I, II, and III, which have mastered planetary, stellar and galactic forms of energy, respectively. Our civilization would be of Type 0, the least advanced. If most of the signals out there are produced by a Type I, II, or III civilization, and if it stands to reason that such advanced civilizations are more likely than not to use some efficient way of encoding a message for deep space transmission with a scheme perhaps similar to the one mentioned above, then our radiotelescopes would be hearing mostly noise.

Dr. Kaku says that the problem is that “the current SETI project only scans a few frequencies of radio and TV emissions sent by a Type 0 civilization,” Thus, we would fail to identify those signals sent by a Type I, II, or III civilization.

The situation is a little akin to an eavesdropper listening in on some internet traffic between different nodes of the network. For instance, the different computers making up the internet talk to each other using a protocol called TCP/IP. Every time a message is sent from one computer to another on this network of networks, the TCP/IP protocol packetizes the message by breaking it into smaller parts called packets. Each of these packets then gets routed to its destination not always in the sequential order of the original message. The receiving computer eventually reconstructs the original message by putting all the packets in the proper order again.

But what would happen if an eavesdropper were to intercept some of the packets on their way to their destination? It would not be clear at all what the message is, especially if our eavesdropper does not possess the packet sequencing information to order the packets he captures according to their original sequence. However, since the eavesdropper would be monitoring only one channel of information, it would be clear to him that he is listening to a non random signal. He could then easily infer that the signal qualifies as an example of intelligent activity even though the message would still remain gibberish.

Unfortunately, in our case we do not even that much to go on when we listen to the chatter of interstellar space. If most signals come from Type I, II, or III civilizations, then chances are that their messaging system is not only sophisticated, but utterly incomprehensible, especially so if they use some sort of encoding system.

We might thus already have received some bona fide signals from elsewhere but were unable to distinguish them from the rest of the noise. Assuming for a moment that the aliens do not use some form of exotic transmission medium that does not rely on the eletromagnetic spectrum, then the question becomes: to decode or not to decode. And if for a Type I, II, or III civilization using the eletromagnetic spectrum is the equivalent of using smoke signals for us, then we stand little chance to find any intelligent signal out there. Unless, of course, we happen to stumble upon the mother lode: a Type 0 civilization looking to the stars for some long lost cousins just like we do.