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In the words of Italian Nobel Laureate Enrico Fermi: "Where is everybody?" What Fermi meant is it's quite surprising we have seen no sign of extraterrestrial intelligence, despite the fact the Universe is so vast and long-lived. This is the essence of the \textbf{Fermi Paradox}.  At this point I often hear saying: "Wait, but what about \href{http://en.wikipedia.org/wiki/Roswell_UFO_incident}{Roswell}... \href{http://en.wikipedia.org/wiki/Roswell_UFO_incident}{Roswell},  the \href{http://en.wikipedia.org/wiki/Wow!_signal}{WOW signal}... signal}, all those  \href{http://en.wikipedia.org/wiki/List_of_reported_UFO_sightings}{UFO sightings}..." sightings}...?"  I am not going into that. I will just state that the most economical explanations for the aforementioned stories have nothing to do with E.T. and that at this time there is no clear evidence proving we had contact with alien life. Let's use \href{http://bit.ly/KDLFp6}{Occam's Razor} and throw away the conspiracy spoon. Back to us. The Fermi Paradox suggests that the number of communicative civilizations $N$ in the Galaxy is small\footnote{Some peculiar solutions to the Fermi Paradox do not require $N$ to be small, see this \href{http://waitbutwhy.com/2014/05/fermi-paradox.html}{post} for a nice discussion}. Our revised version of the Drake Equation then implies two\footnote{Of course the third option is that both $f_i$ and $L$ are small} interesting alternatives: \begin{enumerate}  \item $f_i$ is a small number. \textbf{ Life is common in the Universe, but intelligent life is not}.