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How could different estimates in the Drake equation lead to very different results?
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extraterrestrial intelligence
An artist's conception depicts Kepler-186f, the first Earth-sized extrasolar planet found in its star's habitable zone.
The Drake equation is a formula used to estimate the number of active, technologically advanced civilizations in the Milky Way Galaxy. Because the variables represent complex astronomical, biological, and sociological factors that are currently poorly understood, the equation relies on estimates that are little more than informed guesses.12
The results vary drastically depending on the values assigned to these parameters, particularly the final factor, L (the average lifetime of a technical civilization).12
- Pessimistic Estimates: If one assumes that technical civilizations tend to destroy themselves shortly after developing the capacity for interstellar communication—for instance, if L is only 10 years—the equation suggests that our own civilization may be the only one in the galaxy.12
- Optimistic Estimates: If one assumes that even a small percentage of civilizations survive their own technology and persist for long periods, the estimated number of civilizations can climb into the millions. In this scenario, the nearest advanced civilization might be only a few hundred light-years away.12
Ultimately, the uncertainty increases with each successive factor in the equation, making the final result highly speculative.1