[extropy-chat] The Drake Equation and Spatial Proximity

Eugen Leitl eugen at leitl.org
Mon Oct 23 17:53:23 UTC 2006

On Mon, Oct 23, 2006 at 12:32:12PM -0400, Keith Henson wrote:

> 1.  We are the first (at least inside our light cone).

Why do people have trouble buying this explanation? That we're
in nobody's smart lightcone, I mean? It's perfectly simple and
adequate, a single explanation for all our data, or rather, lack
> 2.  Civilizations don't survive nanotechnology (singularity now) or if they 
> do, they lose interest in the physical universe or (somehow) leave it.

Let's say we're within the lightcone of all such cultures, let's say
10^9 (a pretty small number, actually) of them. What is the chance that all
of those evolve precisely along a very specific trajectory, which
ends in termination (or clean exodus, for all practical purposes
that's the same)? Even a single one of them would be enough to take
a giant spherical bite out of luminous universe (actually, I already 
argued why you can't observe these expansion spheres due to the anthropic 

So all of them evolve exactly the same way, and all of them don't manage
any noteworthy expansion (we've already sent out dumb space probes beyond
this solar system), or sterilize their patch of the cosmic petri dish when
they (silently) implode? Statistically, that's very improbable. Unless we're
in the light cone of very few smart but suicidal critters, which is
actually only a minor variation on 1.
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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