It reminds me of the famous Drake equation: http://en.wikipedia.org/wiki/Drake_Equation http://en.wikipedia.org/wiki/Drake_Equation The most famous 'guesstimat

It reminds me of the famous Drake equation: http://en.wikipedia.org/wiki/Drake_Equation http://en.wikipedia.org/wiki/Drake_Equation The most famous 'guesstimation' based on the Drake equation says there should be something around 10 civilizations in our galaxy. But there are other factors that influence here, like the tendency a civilization has to destroy itself before it reaches the space exploration era (and also the tendency it has to destroy other civilizations) [2] Also, the fact that we have found none yet comes the famous Fermi paradox [2]. Alternative explanations for the seemly inexistence of extraterrestrian civilizations exist, such as impossibility of communication between long distanced civilizations. [2] http://en.wikipedia.org/wiki/Fermi_paradox http://en.wikipedia.org/wiki/Fermi_paradox