Drake Equation

The question of the number of communicating civilizations in our galaxycould, in Drake's view, be reduced to seven smaller issues:

The rate of star formation in our galaxy at the time our Solar System was formed (R*);

The fraction of stars that have planets around them (fp);

The number of planets per star that are capable of sustaining life (ne);

The fraction of planets in ne where life evolves (fl);

The fraction of fl where intelligent life evolves (fi);

The fraction of fi that communicate (fc);

The lifetime of a communicating civilization (L);

Denoting the number of communicating civilization in our galaxy by N, and multiplying the different elements, we get the famous Drake Equation:

N= R* fp ne fl fi fc L  

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