Time-Bounded Kolmogorov Complexity May Help in Search for Extra Terrestrial Intelligence (SETI)

One of the main strategies in Search for Extra Terrestrial Intelligence (SETI) is trying to overhear communications between advanced civilizations. However, there is a (seeming) problem with this approach: advanced civilizations, most probably, save communication expenses by maximally compressing their messages, and the notion of a maximally compressed message is naturally formalized as a message x for which Kolmogorov complexity C(x) is close to its length l(x), i.e., as a \random" message. In other words, a maximally compressed message is indistinguishable from the truly random noise, and thus, trying to detect such a message does not seem to be a working SETI strategy. We show that this argument does not take into consideration the time necessary for compression and decompression of message. If we take this time into consideration, and therefore consider time-bounded versions of Kolmogorov complexity, then the above \problem" disappears. We also show which version of time-bounded Kolmogorov complexity is most appropriate for formalizing SETI strategies. According to modern physics, extra terrestrial intelligence is very probable. According to modern physics, our Universe is largely homogeneous; hence, in many locations, it is possible to have the same physical conditions as the ones that led to the emergence of intelligent life on Earth. It is therefore reasonable to conclude that in many of these places, intelligent life did emerge. A contact with an extra terrestrial intelligence could be highly beneecial for our civilization; hence, SETI. The processes which lead to the emergence and development of intelligent life are far from being deterministic; there are many random factors involved. As a result, the rates with which diierent civilizations appear and progress are expected to be drastically diierent. Hence, we can expect both civilizations which are largely behind us in technological and scientiic progress, as well as civilizations which are way ahead of ours. A contact with such an advanced civilization can bring new knowledge, help us solve our problems, and give a big boost to our civilization. In view of this potential beneet, a lot of eeort goes into Search for Extra Terrestrial Intelligence (SETI); A (seeming) problem with the current SETI strategy. If there are advanced civilizations out there, they, most probably, know about each other and therefore, intensely communicate with each other. In view of this communication, one of the main current SETI strategies consists of watching the radio-signals in the sky and trying to determine which of them …