deletions | additions       diff --git a/Updating Drake Eq.tex b/Updating Drake Eq.tex  deleted file mode 100644  index 1ce9514..0000000  --- a/Updating Drake Eq.tex  +++ /dev/null 
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First a lot has happened since 1961. Some of the terms in the Drake equation are now known, so we can get a simpler form.  $R$, the \textbf{rate of star formation} tells how many stars are born every year in our Galaxy. This number is about 10 and might seem quite small, but the Galaxy is about 10 billion years old, so plenty of stars have born (and died) in the meanwhile. So $R\approx 10$.   $f_p$ Represents the \textbf{average number of planets around a star}.   %We now know that, in average, there is one planet orbiting every star in the Universe. To put it in the words of W. %Borucki, Principal Investigator of the KEPLER satellite: "When you wish upon a star, you are wishing upon a star with %planets". So $f_p \approx$ 1  As already mentioned this number is now known: in average, there is one planet orbiting every star in the Universe \citep{2013ApJ...764..105S,2012Natur.481..167C} which means $f_p \approx$ 1  $n_e$ Is the \textbf{fraction of Earth-like planets}.   As from last year we also know this factor! Earth-like planets are very common. Statistically speaking at least 1 in 5 planets around Sun-like stars could potentially support life \cite{Petigura_Howard_Marcy_2013}. $n_e \approx$ 0.2  So the product of the first 3 terms is now well established and is of order 2.   \begin{equation}  N =\underbrace{\overbrace{R}^{\approx10} \times \overbrace{f_p}^{\approx 1} \times \overbrace{n_e}^{\approx 0.2}}_{\sim 2} \times \underbrace{f_l \times f_i \times f_c \times L}_{?}  \end{equation}\label{Drake}  We can then simplify the Drake equation and re-write it in its "2015 form" as:  \begin{equation}  N \approx 2\, f_l \, f_i \, f_c \, L  \end{equation}\label{Drake_simplified}  The interesting fact about this compact version of the Drake equation is that it only contains factors dealing with the emergence of life itself. Broadly speaking astrophysics has answered the question "Is the Universe likely to provide the right environment for life as we know it ?" with a big "yes!".   Time to deal with astrobiology.  diff --git a/layout.md b/layout.md  index bbb4c2b..94d73c0 100644  --- a/layout.md  +++ b/layout.md 
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Updating Drake Eq.tex  Astrobiology.tex  fc.tex  Derive L.tex