sAt Universe Today, science writer Matt Williams tosses another hypothesis into the ring as to why we don’t see ET: Maybe, universally, everyone is listening but no one is broadcasting. Or few are, anyway. Now why might that be?

He outlines a distinction between two different approaches to the search for extraterrestrial intelligence (ET): SETI and METI

Most efforts to date have been SETI (Search for Extra-Terrestrial Intelligence) where we are looking for them. That encompasses projects like Cornell Astronomer Frank Drake’s pioneer Project Ozma (1960) and the current Allen Telescope Array.

More projects now, Williams says, are METI (Messaging Extra-Terrestrial Intelligence). We could include in that group the three-word Soviet Morse Message (“peace,” “Lenin,” and “SSSR,” radioed into space in Morse Code in 1962). Also the 1679-bit Arecibo Message sent from that telescope in Puerto Rico in 1974, aimed at star cluster M13, 21,000 light years away. Currently, there’s the Breakthrough Initiative, sponsored by Russian billionaire Yuri Milner.

Relative to past METI projects, however, Breakthrough Initiative is very cautious: “To encourage global discussion on the ethical and philosophical issues of sending messages into space, we pledge not to transmit any message until there has been a wide-ranging debate at high levels of science and politics on the risks and rewards of contacting advanced civilizations.”

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