What is Messaging Extraterrestrial Intelligence (METI)?

Deliberate Earth broadcasts aimed at contacting extraterrestrials could permanently reveal our presence.

Summary

METI is a technically deliberate extension of the search for extraterrestrial intelligence: rather than merely listening, it constructs and broadcasts signals intended to initiate contact. The strongest mainstream concern is not that transmission is impossible, but that humanity lacks reliable knowledge of extraterrestrial intentions, capabilities, or the consequences of announcing our presence. That uncertainty supports international debate and governance before powerful transmissions continue.

• CommunicationMessages must account for encoding, length, information content, cultural bias, transmission method, and repetition.
• GovernanceDecisions with potentially species-wide consequences should not rest solely with a small number of technically capable transmitters.
• RiskThe consequences of contact cannot currently be predicted from available evidence.

• METI uses powerful communications equipment to transmit intentional messages toward unknown extraterrestrial intelligences.setiathome +1
• A proposed METI protocol addresses signal encoding, message length, information content, anthropocentrism, transmission method, and periodicity.arxiv
• Critics argue that extraterrestrial reactions, intentions, and capabilities are presently unknowable, making broad international deliberation important.setiathome