Aliens need a lot motime to find us

There is only the echo.

--- In spacesettlers@yahoogroups.com, "Omar E. Vega"
>
> I am afraid there is only a clear result.
>
> SETI has not find any green monster at all during its 40 years
> search. No live whatsoever has been found in the solar system as
> yet, either.
>
> For me, that means the probabilities of finding an allien
> civilization in this galaxy have been falling continuously.
>
> Perhaps, because we are actually alone! That's all.
>
> Omar
>
> --- In spacesettlers@yahoogroups.com, joe@ wrote:
> >
> > On Jan 22, 2007, at 02:28 UTC, Alex Michael Bonnici wrote:
> >
> > > "So, where is everybody?" Nobel laureate Enrico Fermi reportedly
> > > quipped to fellow physicists in 1950, when discussing why we
> haven't
> > > seen any signs of alien civilisations if, as many believe, our
> galaxy
> > > is teeming with life. Now, a maths model may have an answer to
> > > Fermi's paradox. Rasmus Bjork of the Niels Bohr Institute in
> > > Copenhagen has calculated that eight probes " travelling at a
> tenth
> > > of the speed of light and each capable of launching up to eight
> sub
> > > -probes " would take about 100,000 years to explore a region
> of space
> > > containing 40,000 stars.
> >
> > ..quoting a bit further: "When Bjork scaled up the search to
> include
> > 260,000 such systems in our galaxy's habitable zone, the probes
> took
> > almost 10 billion years - three-quarters the age of the universe -

> to
> > explore just 0.4 per cent of the stars"
> >
> > So, let's review: it takes ridiculously long to explore the whole
> > galaxy with 64 non-replicating probes. ...Umm, OK... but the
> relevance
> > of this is not clear to me. In real life, we wouldn't be talking
> about
> > a cilivization sending out eight probes (each with eight sub-
> probes)
> > and then sitting on their hands for ten billion years. We'd be
> talking
> > about cilivizations expanding from star to star. This is a
> > population-growth situation, not a fixed-number-of-probes
> problem. The
> > growth is basically exponential, until the galaxy starts getting
> full.
> > A few hundred million years is all it takes to reach that point.
> >
> > It amazes me that otherwise respectable scientists (like Drake)
and
> > mathematicians (like the Bjork guy) continue to make such basic
> > mistakes. They need to get some friends in the ecology
department,