Carl Sagan explaining the Drake equation:
N = R*•fp•ne•fl•fi•fc•L “In 1961, Carl’s close friend, fellow astronomer Frank Drake, created an equation for calculating the number of intelligent civilizations in the galaxy.” The Drake equation is: N = R*•fp•ne•fl•fi•fc•L where: N = the number of civilizations in our galaxy with which communication might be possible (i.e. which are on our current past…