Mr. Moe

I am going to paraphrase a little part of Cosmos by Carl Sagan.

Use the equation N = (N*)(FP)(NE)(FL)(FI)(FC)(FL)

Where
N*=The number of stars in the milky way (estimated at 4x10^11)

FP=The fraction of stars that have planetary systems (estimated at 1/3)

NE= The number of planets in a given system that are ecologically suitable for life (assuming that Jupiter, Titan, Mars, Europa and of course Earth could be capable of sustaining life in our own solar system, this isn't very rare. Sagan estimates it around 2)

FL= The fraction of otherwise suitable planets on which life actually arises (the basic molecular basis of life is readily made in the most common cosmic conditions, as in compounds that can copy themselves. This fraction is again estimated at 1/3.)

So far there are 1x10^11 planets that may have a simple form of life on them

FI=The fraction of inhabited planets on which an intelligent form of life evolves
FC= the fraction of planets inhabited by intelligent beings on which a communicative technical civilization develops (we can group these together, and assume that it is very unlikely that we as humans derived as intelligent beings, however there are many many many other possible steps to form intelligent beings. So Sagan estimated it at 1/100, 1% of all life carrying planets have had an intelligent civilization)

FL= The fraction of planetary lifetime graced by a technical civilization. (How quickly do these civilizations kill themselves off? Using us as an example, we have lived on the earth for 1/10^8 of the earth's total existence. And we could destroy ourselves tomorrow.)

Putting all these numbers into the equation. N=10. This number could be as low as 1, or much higher depending on a few of the variables. So at any given time, in our galaxy, only 10 civilizations are at least capable of our technology. This in my opinion means that it is very, very unlikely that we will ever come across one of them.