A protocol for messaging to extraterrestrial intelligence

3. Developing a protocol for messaging to extraterrestrials

Sending a message to an unknown extraterrestrial intelligence may require a loosening of the anthropocentric assumptions that have characterized previous METI attempts. Most communication between humans on Earth relies on vision and sound because of the specifics of our biology, but we cannot necessarily assume that extraterrestrials will share any of our basic senses. The dependence on visual imagery in the Arecibo message, for example, necessitates that the recipients can interpret information stored as pictures. However, a subsurface life form is less likely to develop visual sensory perception, and not even all life on Earth is vision-oriented (e.g. bats) or auditory (e.g. invertebrates). Likewise, while we expect that the basic physics of compression waves applies throughout the universe, not all life forms will necessarily develop a sense of hearing. Messages that rely on the specifics of human biology or culture will be less likely to effectively communicate to an unfamiliar extraterrestrial listener.

Additionally, the information content of METI signals has increased since the initial Arecibo message. Modern technology allows for large amounts of data to be transmitted at moderate cost, but the broadcast of massive amounts of information assumes that the recipient extraterrestrials will be capable of comprehending a complex message. Even if advanced extraterrestrial technology can decode a massive message with ease, a society of blind extraterrestrials would be unsuccessful at retrieving the information from a visual message just as deaf recipients would be unable to understand an auditory message. Extraterrestrials may identify a signal containing video or music as originating from Earth-based life because its complexity resembles nothing else found in nature, but they may have little to no success at comprehending the information within an overly complex message. Thus, it is imperative that any message intending to communicate with extraterrestrials be short and simple enough that it can be understood by the widest possible audience.