A Brief History of METI: Early Attempts to Message Extraterrestrial Intelligence

For centuries, humanity has gazed at the stars, wondering if we are alone. This enduring question—often called the 'Great Silence'—has fueled both science and imagination. The search for extraterrestrial intelligence, or SETI, has primarily focused on listening for signals from other civilizations. However, a more proactive approach, known as Messaging Extraterrestrial Intelligence (METI), involves transmitting deliberate signals into space in the hope of making contact. The history of METI is rooted in early theoretical ideas and experimental efforts that emerged alongside the space age. Pioneering scientists and thinkers, including figures like Frank Drake and Carl Sagan, played key roles in shaping the debate over whether we should announce our presence to the cosmos. Their early experiments, such as the famous Arecibo message of 1974, marked a turning point in our relationship with the universe. Understanding this history matters because it frames ongoing discussions about the risks and rewards of active SETI. As technology advances and more exoplanets are discovered, the question of whether to transmit—and what to say—becomes increasingly urgent. The legacy of these early ideas continues to influence modern METI projects and the global scientific community's cautious approach to reaching out across the stars.