Ok, so you are setting the scale as "from the present conversation back to formation of Earth" and saying that this is large in comparison to "from formation of

Ok, so you are setting the scale as "from the present conversation back to formation of Earth" and saying that this is large in comparison to "from formation of Earth to formation of RNA". However, I respectfully don't see how this scale has any bearing on the probability of life forming around another system. Formation of life is certainly a prerequisite to the formation of intelligent life (the two events in question). Both could have a probability of occurring much smaller than 10^-24 (approximate # of finite stars in observable universe).