> I think the odds of a planet developing life by random chance in the first place is astronomical, and then the odds of that developing into intelligent life -

> I think the odds of a planet developing life by random chance in the first place is astronomical, and then the odds of that developing into intelligent life - that happens to have the necessary appendages to build things and lives in an environment amenable to creating tech - almost certainly an astronomically small portion of life bearing planets. Let's start from what we know: homo sapiens has been around for 300 000 years, but technology only kicked of less than 300 years ago. So we could say that of 3 billion years of terrene life, 0.01% of it have sported a species susceptible to develop technology, and of this short span only 0.1% of it actually developing it. So from Earth example, so far we can only posit 1 chance out of 10 millions of developing technology, nothing more. That's not much, and that's markedly lower than Drake's original optimistic numbers. Also, we can't suppose technology will survive for a very long time; so we also need a very fine time-alignment to receive a message (or get someone to receive ours). If most high tech civilisations only survive barely a few centuries, even if there are 100 000 of them across the Galaxy but scattered along 10 billion years, most messages simply will reach long rusted antennas...