deletions | additions       diff --git a/In_order_to_estimate_the__.tex b/In_order_to_estimate_the__.tex  index e4884e4..0cc3f2d 100644  --- a/In_order_to_estimate_the__.tex  +++ b/In_order_to_estimate_the__.tex 
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In order to estimate the number of technological civilizations that might exist among the stars, in 1961 Frank Drake proposed the a  \href{https://www.authorea.com/users/2/articles/11048/_show_article}{simple equation} above. Here equation. Below  you can play with an interactive plot showing the number $N$ of communicative civilizations in the Galaxy as function of their average longevity $L$. You can change the values of the various parameters using the sliders.