A search for optical beacons: implications of null results

David Blair, M.G. Zadnik

    Research output: Contribution to journalArticle

    2 Citations (Scopus)


    Over the past few years A series of searches for interstellar radio beacons have taken place using the Parkes radio telescope. Here We report hitherto unpublished results from a search for optical beacons from 60 solar-type stars using the Perth-Lowell telescope. We discuss the significance of the hull,results from these searches, all of which were based on the interstellar contact channel hypothesis. While the hull results of all searches to date can be explained simply by the nonexistence of electromagnetically communicating. life elsewhere in the Milky Way, four other possible explanations that do not preclude its existence are proposed: (1) Extraterrestrial civilizations desiring to make contact through the use of electromagnetic beacons have a very low density in the Milky Way. (2) The interstellar contact channel hypothesis is incorrect, and beacons exist at frequencies that have not yet been searched. (3) The search has been incomplete in terms of sensitivity and/or target directions: Beacons exist, but more sensitive equipment and/or more searching is needed to achieve success. (4) The search has occurred before beacon signals can be expected to have arrived at the Earth, and beacon signals may be expected in the future. Based on consideration of the technology required for extraterrestrial civilizations to identify target planets, we argue that the fourth possibility is likely to be valid and that powerful, easily detectable beacons could be received in coming centuries.
    Original languageEnglish
    Pages (from-to)305-312
    Issue number3
    Publication statusPublished - 2002

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