[ExI] Where are they? was Re: 2^57885161-1

[Eugen Leitl]

On Tue, Feb 19, 2013 at 12:06:43PM -0800, spike wrote:

> Granted that is the simplest explanation but it isn't the most obvious to
> me, after I gaze at that NASA deep space image.  When I gaze deeply into
> that abyss until it gazes back into me, I cannot fathom that we are the
> first and only.

We need a sample not causally correlated with us, which probably
excludes the entire solar system (unless it's obvious that
there have been several, independant life emergence events,
not hopelessly overgrown by impact ejecta crosscontamination). 

Even if you can detect abundant life by spectroscopy across
a population of 10^4 of stars in our direct neighborhood,
it doesn't tell you about life that is smart enough to
be expansive. Because you need at least one independant
sample to estimate the other coefficients of the Drake
equation.

Expansive life doesn't just gaze, it visits. And changes
stellar system in its wake.