deletions | additions       diff --git a/It_is_a_product_of__.tex b/It_is_a_product_of__.tex  deleted file mode 100644  index 0c227c3..0000000  --- a/It_is_a_product_of__.tex  +++ /dev/null 
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It is a product of factors giving the number $N$ of civilizations in the Milky Way Galaxy with whom we could make contact. The terms in the equation are:  \begin{itemize}  %\item $N$ is the number of civilizations in the Milky Way Galaxy with whom we could make contact.  \item $R$ is the rate of star formation, which tells how many stars are born every year in our Galaxy.  \item $n_e$ is the average number of habitable planets in any planetary system  \end{itemize}  All the $f$ terms are factors $\le 1$:  \begin{itemize}  \item $f_p$ is the fraction of stars that have planets   \item $f_l$ is the fraction of planets hosting life  \item $f_i$ is the fraction of life-bearing planets that develop an intelligent life-form  \item $f_c$ is the fraction of intelligent life-forms that decide to communicate  \end{itemize}  Finally $L$ is the longevity of a communicative civilization (in years). Humankind has been "communicative" only for a few decades and it's hard to predict what $L$ will be for us. However I think that the current lack of detection of E.T. communications could be used to put some limits on the longevity of an average civilization.   More on this in the following.   diff --git a/layout.md b/layout.md  index 44a3131..3fcbf89 100644  --- a/layout.md  +++ b/layout.md 
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Equation.tex  figures/Drake3/Drake_Annotated.jpg  It_is_a_product_of__.tex  Updating Drake Eq.tex  Astrobiology.tex  fc.tex