[ExI] Fermi question, was is a FTL drive a dream . . .

[Eugen Leitl]

On Tue, Dec 20, 2011 at 04:34:43PM -0500, Mike Dougherty wrote:

> Could military-grade communications specialists from 1950 even detect
> (much less understand) today's spectrum-hopping (et al) technology
> used in something as backwards as a cordless phone?  Would HD Radio
> make sense under examination using the tools of the day?  Would even
> stereo FM be obvious to any but a few nerds in the world? (who may
> have been on other projects at the time)
> 
> Do we have the right technology to interpret the signals around us?

You're describing the classical problem of SETI: the observability
window is narrow. The brightest monochromatic sources we used was
military radar so we're detectable to within some 300 lightyears
http://www.abc.net.au/science/articles/2010/07/13/2952471.htm

Our total observability window was only about a century.
 
> What if we can't find anything because we're just not clever enough
> (yet) to see what is everywhere?

The problem is not being clever, the problem is the issue of
power.

If you look at single stellar FIR sources, the range is much
enhanced http://home.fnal.gov/~carrigan/infrared_astronomy/Fermilab_search.htm

But given expansiveness they'd be impossible to miss even at 
GLyr distances. (Of course if you can observe them, they would
have passed here already, and you would never have happened,
so they're not observable).
 
> I know, pointless speculation... can't do anything if it's true...
> let's talk about some other pointless nuance of this paradox. (right)

There is no paradox. Anthropic principle and relativistic expansion
as well as long time to observer creation and brief observer existance
makes the odds of observing one half of the sky going dark very low.