Anthony Cerrato wrote:

"Paul Bramscher" <brams007_nospam@tc.umn.edu> wrote in
message news:cimpg4$dhk$1@lenny.tc.umn.edu...

Peter Hickman wrote:

Mike Williams wrote:

[snippage]

If there's on thing that's for sure, though, it's that

cities (as a

whole, whatever their rationale) have persisted longer

than radio

communications.  They'll likely last longer than radio

communications,

if current trends in technology continue at such a

breakneck pace.  And

so maybe the most fruitful SETI searches will result from

(when

technology allows) search for extra-terrestrial cities.

Whether we can

do this optically, chemically or via some other signature,

a city is not

necessarily required for a sign of intelligence (hermits,

nomads and

Simak's "City" are counter-examples), but when a city *is*

found, we

might certainly say that we have found intelligence...

Besides cities have a political dimension. People will

want to be near

the seat of power. Cities will happen if power is

wielded from a given

location. Also population pressure will create cities as

people simply

have less space between them. Then there is the fact

that large

concentrations of people allow sub cultures to flourish.

If 1% of the

population like theatre then a town of 1000 people will

probably not

have much of a theatre scene, now 1% of a multimillion

city and you have

a vibrant scene.

The Japanese have a saying about ex pat communities.

1000 people per

restaurant. There will be no decent Japanese restaurant

(that the

Japanese would eat at) until you have at least 1000

people (Japanese) in

the area to frequent it.

Cities are important for the development of

civilizations.

I too think that cities will remain the mainstay of ETIs
derived from _"life as we know it"_ throughout their
lifetime. There is no doubt that the majority of long-lived
ETI societies would undergo diasporas into interstellar
space (including generation ships and O'Neil type colonies)
and many will undergo a thinning of population for various
periods and society-segments due to this dispersion, as well
as due to improved/rigorous population control/optimization
techniques/laws (particularly if they develop near
immortality.)

Even for civilizations which develop fears of exploration or
contact with other ETIs (particularly true with near
immortals) and withdraw to their own planet, and /or
isolated communities or homes, at least some trace(s) of
cities will remain, if only for historical reasons. Even
when societies die off, artifacts of some cities will remain
for at least some time which might allow detection by
various methods. I do still think though that the average
lifetime of any such societies (including their interstellar
colonies) will be far less than the order of, say, a million
years.

After I wrote my post of the reemergence of the city in terms of social usefulness, I read a news article that suggests the majority of Chinese city dwellers are in lower-health situations and have a lower life expectancy (only 58 years) compared to the national average of 72.  And we can't forget the effects of plagues in Europe.  It may very well be that cities are somewhat double-edged swords with regard to their utility in light of disease, congestion, stress, pollutants, etc.

So I wonder if a high-tech alien species will solve this problem by dispersal to the countryside, or conquer basic disease, environmental, and transportation issues.

On the issue of disease and close proximity, maybe they (and we?) hope to achieve bee-like success.  Beehives are widely regarded as some of the most sterile naturally occuring places on Earth in our ordinary temperature range (between freezing and boiling) because of propolis.