Alien Civilization Calculator (Drake Equation)

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Drake (1961) multiplies seven sequential filters. The Copernican model (Westby & Conselice 2020) uses stellar age, metallicity, and a fixed communication lifetime instead.
Average rate at which new stars are born in the Milky Way each year. Current estimates range from 1.5 to 3 stars/yr.
stars/yr
Fraction of those stars that have a planetary system. Exoplanet surveys suggest this is close to 1.
Average number of planets per solar system that could potentially support life. Often estimated between 0.1 and 1.
planets
Fraction of those planets where life actually develops. This is highly uncertain, ranging from near 0 to near 1.
Fraction of life-bearing planets where intelligence eventually evolves. One of the most debated parameters.
Fraction of intelligent civilizations that develop detectable communications technology and choose to use it.
How long a civilization remains detectable. Estimates span 300 years (self-destruction risk) to millions of years.
years
Radius of the Milky Way disk in light-years. Commonly used value is ~50,000 ly.
ly
Civilizations in the Milky Way (N)We may be alone
0.6

Estimated number of communicating civilizations detectable right now

Nearest civilization distance40,300ly
Detection probability within 1,000 ly0.01%
Civilizations per 1,000 ly cube0
0.01%
Effectively zero<1%Very unlikely1%-10%Possible10%-50%Likely50%-90%Almost certain90%+

Your assumptions suggest the galaxy is silent.

  • Your parameters predict fewer than one detectable civilization - meaning we might genuinely be alone in the Milky Way right now.
  • The nearest expected civilization is about 40,300 light-years away - very far away. At radio-wave speed, a message there would take that many years one-way.
  • There is less than a 1% chance of a civilization within 1,000 light-years - silence in SETI surveys is statistically expected.
  • The Drake Equation is a product of uncertain factors; changing the lifespan (L) by a factor of 10 shifts N by the same factor. The result spans many orders of magnitude depending on your assumptions.

Next stepAdjust the civilization lifespan (L) first - it has the biggest leverage on N. Then explore how the life-emergence fraction (fl) and intelligence fraction (fi) change the picture.

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