ETL Flashcards
Who came up with an equation to estimate ETL?
Frank Drake
When did he do this?
In 1961
Who modified this equation?
Astronomer Carl Sagan
In what year did Carl Sagan modify the equation?
In 1978
Why was the equation modified?
For the TV show Cosmos
What is the equation?
N=n*xfpxnexflxfixfcxfL
What does N=?
N= number of communicating civilisations now existing in our galaxy
What does N*=?
Number of stars in galaxy
What does fp=?
Fraction of stars in planetary system
What does ne=?
Number of life capable worlds in a system
What does fl=?
Fraction of those worlds where life develops
What does fi=?
Fraction of these worlds where intelligent life develops
What does fc=?
Fraction of those worlds where a civilisation able to communicate develops
What does fL=?
Fraction of a world’s lifetime that a communicative civilisation lasts for
