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?

That's my take.

It seems without a strong stimulus the impetus is lacking.

Depends on how much it costs. I see slight extrapolations of current technology as bringing that cost way down. It will eventually be cheap to explore and inhabit the solar system, and this will make it very cheap to start using a major fraction of the sun's energy, to the point where even interstellar travel would become feasible. If it's feasible, someone will do it.

And when we do feel like communicating, will we decide to start
broadcasting radio waves fiercely enough to be detected by one of the
local star systems using the same technology we presently use?

What, other than electromagnetic radiation, would you suggest? If we want to communicate with hypothetical aliens, what else is there?

It seems to me that your first statement assumes that there will be no advance in technology, such that communication and travel are forever prohibitively expensive, and your second assumes there will be a fundamental breakthrough in physics that's incomprehensible to current science. Which seems mutually contradictory.

Seems
unlikely to me. And does the drake equation take into account the
number of star systems within a given range. The farther the system
the less likely we are to detect any kind of signal.

No, the Drake equation attempts to calculate the density of civilizations in the galaxy, from which you could calculate mean range if you wanted to. If there are very few civilizations, and if they don't travel or send out probes, you have a point. But I think, if humans are a guide, that they eventually would do both. And a very slow rate of expansion fills up the galaxy rather quickly in geological terms.