dps@sri-unix (11/19/82)
If I were to try to advise other intelligences in the galaxy of my existence, I would pick a clear and distinctive way to do it. The plaque used on Pioneer seems to me a muddy way to do it. The message is too high level and too dependent on understanding our way of percieving the universe around us. I would, instead, pick a tight focus transmission (e.g., masers or lasers), aim it first at nearby stars, and send a unique transmission. To make as clear as possible that the transmission was not a natural phenomenum, like a pulsar of complex period, I would send at least 3 channels with distinct patterns. The main channel, for instance, could send SOS in good old morse. A second channel, would send . -- ... ---- perhaps, representing the first four integers. The third channel might send either a morse alphabet, or a sequence of binary numbers (how many bits per number? how do you seperate numbers? Do you use straight binary, or a Gray code?). The point of these three channels is to send a set of very short, very repetitive (low-level) messages *each differing from its companions in period* which will identify themselves as messages. It is also hoped that the message is simple enough to be properly decoded. Only after decoding these messages (a kind of rosetta stone) would any transmission of text be reasonable. Otherwise, the message would contain too much information to be decoded, and contain too many assumptions on the nature of decoding. Yes, English (particularly written English) is highly redundant, and analyzers can easily find its patterns, but the analyzers are human and understand the channel and the type of messages it is used for, and the redundancy is on a fairly high level. An alien coming on English text, and if in the form of radio transmissions it would not even represent in form the senses we percieve the universe with *and thus remove many decoding clues*, would lack the knowledge of how we convey emotion and emphasis -- very important decoding tools for written English. A maser/laser transmission would not, of course, be done from the Earth's surface. It could be done from, say, a geo-synchronous orbit, aiming at different targets day and night. (The 24 hour period superimposed might provide more interest for alien analyzers). Or, if this leaves the signal too swamped by Sol's output, the platform might have to be boosted out of the plane of the ecliptic...how far out would be needed for a transmission to Alpha Centauri or Barnard's Star?