[extropy-chat] Fw: [atlantis_II] Re: fermi's paradox: m/d approach

[Harvey Newstrom]

I wrote,
> It seems clear that we are a new 
> civilization with our signals going out only a hundred light 
> years or so.

This is based on the earliest possible signals when Marconi transmitted
wireless telegraph just before 1900.    But it now occurs to me that they
bounced such radio waves off the ionosphere to get around the curve of the
earth.  I am not sure when radio waves started going out into space, or when
they became numerous or interesting enough to be detectable.  The first
radio network was NBC starting in 1926.  The first big or powerful
transmitters were built by RCA after 1934.  We may have only about 65 years
of transmitting to space.  For a round-trip signal, that limits responses to
about 30 light-years or less, if they detected us instantly and responded.
Any delay in detection or answering, and our globe of possible civilizations
to talk to is reduced even further.  There are 106 stars within 20
light-years according to
<http://www.anzwers.org/free/universe/nearstar.html>.  Only 6 of these are
yellow G-class stars.  If the likelihood of advanced civilizations is less
than 1/7 (14%) of G-class stars, we may be the only civilization within this
response cone.  There may be no civilizations close enough to have heard us
and answered us yet.

-- 
Harvey Newstrom, CISSP, CISA, CISM, IAM, IBMCP, GSEC
Certified IS Security Pro, Certified IS Auditor, Certified InfoSec Manager,
NSA Certified Assessor, IBM Certified Consultant, SANS Certified GIAC
<HarveyNewstrom.com> <Newstaff.com>