Max wrote:

On Aug 14, 12:41 pm, John Harshman <jharshman.diespam...@pacbell.net>
wrote:

Paul J Gans wrote:

In talk.origins John Harshman <jharshman.diespam...@pacbell.net> wrote:

K_h wrote:

Fermi's paradox suggests that there are little or no other intelligent
civilizations within the Milky Way galaxy.  On the other hand, intelligent
life should exist on a substantial fraction of planets with life because
natural selection broadly increases intelligence with time.

Does it? News to me. What evidence do you have that this is the case?

There is also the problem that there could easily be more than one
kind of intelligence.  Many living (and non-living) things respond
to stimuli.  At what point does that become intelligence?
Does the definition of intelligence require that television be
invented?

I believe that the operational definition of intelligence as used in the
Drake equation does require this, or at least an intelligence capable of
inventing interstellar communication and/or travel.

That is, in the Drake equation, f_L should be far
smaller than most people think it is.  Even on planets that are life
friendly the formation of life should be extremely rare for the below
reasons.

The Drake equation assumes that the ETs will be blasting out
electromagnetic waves at a furious rate.  *We* started doing
that only in around 1920 or so and already we are doing less
and less of it.  By 2120 we could easily be using wired or
directed sources and no indiscriminate electromagnetic radiation
at all.

Yes, one solution would be for all civilizations to render themselves
undetectable very soon after becoming detectable. This assumes they
don't go in for travel or communication, and never make noticeable
changes to their habitat (like Dyson spheres and such). It seems to me
that this assumption would require humans to be a very unusual sort of
intelligence, because we're going to go in for communication and travel
as soon as we figure out how, if we don't collapse first.

Will we? It seems without a strong stimulus the impetus is lacking.

I agree with you that it's unlikely that humans will utilize a significant fraction of the power of the Sun just to send messages into a Galaxy they believe is probably lifeless anyway.

For such a thing to occur, we're going to need to already detect another extraterrestrial civilization beaming messages to us (proving that they do exist).  Or at least have made enough progress on the first 4 or 5 terms of the Drake Equation:  That is, find some extrasolar planet where there are *some* forms of life, even if not yet technologically advanced.

Right now, we don't even know if *life* is a fluke unique to the Earth, let alone intelligence.  So let's stop jumping the gun here.  The first order of business is to detect *life* in the Universe.  That would be a "strong stimulus" that intelligence might also exist out there.