I remember reading an article in the Guardian last year with title "Our galaxy may contain billions of planets with the same mass as Earth". Surely, it is valid scientific guess as it is but if it is really true, my first thought would be that intelligent life as we know it (assuming we are intelligent species) is as rare as we can imagine. If they are not, the big question is why we are still not able to detect any single proof of their existence or still not eaten by some violent alien species? The only logical answer that we are first one walks on the edge of impossibility to me. Most likely we are missing something important, a discovery as important as fire was. While this statement is still accurate and generally speaking plausible, let's think a little more about it. So to start with the original statement, is there really that many planets with Earth like properties in our galaxy? Ever since I read the Drake equation for the first time (shown above), I coul...