Are you sure we are alone?

The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Galaxy.

 

 

There is considerable disagreement on the values of these parameters, but the 'educated guesses' used by Drake and his colleagues in 1961 were:

 

R∗ = 1 yr−1 (1 star formed per year, on the average over the life of the galaxy; this was regarded as conservative)

fp = 0.2 to 0.5 (one fifth to one half of all stars formed will have planets)

ne = 1 to 5 (stars with planets will have between 1 and 5 planets capable of developing life)

fl = 1 (100% of these planets will develop life)

fi = 1 (100% of which will develop intelligent life)

fc = 0.1 to 0.2 (10–20% of which will be able to communicate)

L = somewhere between 1000 and 100,000,000 years

 

Inserting the above minimum numbers into the equation gives a minimum N of 20 (see: Range of results). Inserting the maximum numbers gives a maximum of 50,000,000. Drake states that given the uncertainties.

 

The original meeting concluded that N ≈ L, and there were probably between 1000 and 100,000,000 planets with civilizations in the Galaxy.

 

 

Makes you think we might not be alone.

 

 

 

Done