The Drake Equation was developed in the 1960's by Frank Drake to estimate the number of possible intelligent civilizations in our galaxy capable of radio communication. It uses a number of key variables, many of which at present are unknown, to arrive at an educated guess of the number of possible civilizations present in our Milky Way galaxy.

The BBC has developed an interactive calculator with an added variable which yields an estimate of possible civilizations not only in the Milky Way, but of the universe itself. The revised Drake Equation uses the following variables :

N= R *f_p* n_e*f_l* f_i* f_c* L * n_r

R is the number of new stars born each year

Fp is the number of stars with planets

Ne is the number of habitable planets per solar system

Fl is the % chance a habitable planet develops life

Fi is the % chance that life develops intelligence

Fc is the % chance that life can communicate across space

L is the length of time a civilization sends signals into space

Nr is the number of times a civilization could redevelop

Using the BBC calculator fill in the chart below:

Outcomes

Are you a skeptic or an optimist when it comes to believing in alien civilizations?

How might we get a better handle on the variables in the Drake Equation? Are our values any different today than the initial values Drake came up with?