deletions | additions       diff --git a/Derive L.tex b/Derive L.tex  index 47ad31a..5537c73 100644  --- a/Derive L.tex  +++ b/Derive L.tex 
...
L_c \sim V^{1/4},  \end{equation}  which states that at any given time the minimum value for the number of galactic communicative civilizations in order to achieve contact is given by the volume of the galaxy to the power 1/4. Note that at the same time this number is also the minimum communicative phase lifetime required for contact. The absenece of a contact then allows to assess that in our Galaxy $L$10^{12}-10^{13}$ 10^{12}-10^{13}  cubic light years: therefore in our Galaxy $L1000-2000 1000\...2000  years.