Drake equation - Galaxy T-Shirt

The Drake equation (sometimes called the Green Bank equation or the Green Bank Formula) is an equation used to estimate the number of detectable extraterrestrial civilisations in the Milky Way galaxy. It is used in the fields of exobiology and the Search for ExtraTerrestrial Intelligence (SETI). The equation was devised by Frank Drake, Emeritus Professor of Astronomy and Astrophysics at the University of California, Santa Cruz. In 1960, Frank Drake conducted the first search for radio signals from extraterrestrial civilisations at the National Radio Astronomy Observatory in Green Bank, West Virginia. Soon thereafter, the National Academy of Sciences asked Drake to convene a meeting on detecting extraterrestrial intelligence. The meeting was held at the Green Bank facility in 1961. This meeting established SETI as a scientific discipline. The meeting's dozen participants — astronomers, physicists, biologists, social scientists, and industry leaders — became known as the "Order of the Dolphin". The Green Bank meeting has been commemorated by a plaque at the site. The Drake equation is closely related to the Fermi paradox in that Drake suggested that a large number of extraterrestrial civilisations would form, but that the lack of evidence of such civilisations (the Fermi paradox) suggests that technological civilisations tend to disappear rather quickly. This theory often stimulates an interest in identifying and publicising ways in which humanity could destroy itself, and then counters with hopes of avoiding such destruction and eventually becoming a space-faring species. A similar argument is the Great Filter,[2] which notes that since there are no observed extraterrestrial civilisations, despite the vast number of stars, then some step in the process must be acting as a filter to reduce the final value. According to this view, either it is very hard for intelligent life to arise, or the lifetime of such civilisations must be relatively short. Carl Sagan, a great proponent of SETI, quoted the formula often and as a result the formula is sometimes mislabeled as "The Sagan Equation."