How many civilizations might exist in our galaxy?
The Drake Equation gives an answer - but it could be 1 or 10 million.
The answer
In 1961, astronomer Frank Drake created an equation to estimate the number of communicable civilizations in the Milky Way by multiplying factors like the rate of star formation, the fraction of stars with planets, the fraction where life develops, and how long civilizations last. Depending on the assumptions, the answer ranges from just 1 (us) to millions. The equation's genius is not in giving a definitive answer but in structuring our ignorance - identifying exactly which factors we need to learn more about. Recent exoplanet discoveries have constrained some terms, but the longevity of technological civilizations remains the most uncertain variable.
Source: SETI Institute
- Drake equation
- SETI
- astrobiology
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