Interstellar messages

Source: Wikipedia. Pages: 72. Chapters: Extraterrestrial life, Fermi paradox, Carl Sagan, Drake equation, SETI, Lincos, Ann Druyan, Frank Drake, Voyager Golden Record, Habitable zone, Communication with Extraterrestrial Intelligence, Jon Lomberg, Alien language, Pioneer plaque, Active SETI, Arecibo message, Time capsule, List of interstellar radio messages, A Message From Earth, Aleksandr Leonidovich Zaitsev, Bracewell probe, Interstellar communication, Metalaw, Iosif Shklovsky, Cosmic Call, Hans Freudenthal, Teen Age Message, Nikolai Kardashev, The Morse Message, Hello From Earth, Across the Universe, Linda Salzman Sagan, Prix Guzman, CosmicOS, San Marino Scale. Excerpt: The Fermi paradox (Fermi's paradox or Fermi-paradox) is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilizations and the lack of evidence for, or contact with, such civilizations. The age of the universe and its vast number of stars suggest that if the Earth is typical, extraterrestrial life should be common. In an informal discussion in 1950, the physicist Enrico Fermi questioned why, if a multitude of advanced extraterrestrial civilizations exists in the Milky Way galaxy, evidence such as spacecraft or probes is not seen. A more detailed examination of the implications of the topic began with a paper by Michael H. Hart in 1975, and it is sometimes referred to as the Fermi¿Hart paradox. Other common names for the same phenomenon are Fermi's question ("Where are they?"), the Fermi Problem, the Great Silence, and silentium universi (Latin for "the silence of the universe"; the misspelling silencium universi is also common). There have been attempts to resolve the Fermi paradox by locating evidence of extraterrestrial civilizations, along with proposals that such life could exist without human knowledge. Counterarguments suggest that intelligent extraterrestrial life does not exist or occurs so rarely or briefly that humans will never make contact with it. Starting with Hart, a great deal of effort has gone into developing scientific theories about, and possible models of, extraterrestrial life, and the Fermi paradox has become a theoretical reference point in much of this work. The problem has spawned numerous scholarly works addressing it directly, while questions that relate to it have been addressed in fields as diverse as astronomy, biology, ecology, and philosophy. The emerging field of astrobiology has brought an interdisciplinary approach to the Fermi paradox and the question of extraterrestrial life. The Fermi paradox is a conflict between an argument of scale and probability and a lack of evidenc