In article <y0snc.91055$7a5.48783@bignews6.bellsouth.net>,
stephen voss <voss749@bellsouth.net> wrote:

1) If youre going to realistically maintain long term interstellar
communication youre going to have to develop reliable FTL 
communication...which we cannot currently detect.

The current belief is that FTL *communication* is physically impossible.
Whilst current theories may prove incorrect, one must, assume that
the most likely development course for technological civilisation
doesn't require it.  You could argue that technological civilisation
will die with their stars without it, but you can't say that it must
be possible because technological civilisation require it for their
survival.

5) expansions of civilizations is not a steady thing, civilizations have
boom periods, decline periods, and some civilizations may just decline
to nothing.

I'm afraid that this may be the fate of humanity, but if it isn't,
mankind will have to leave the earth before the sun engulfs it, 
which will be a long time before the heat death of the universe.

(At least one reason for a civilisation going active, in a SETI 
sense, might be its imminent extinction, when it hadn't left its home
planet and no longer had the resources to do so.  The germ line might not
be preserved, but much of a civilisation's inheritance is extrasomal.)