Re: Estimates of life in the universe

In article <FpGei.3535$19.1964@xxxxxxxxxxxxxxxxxxxxxx>,
george@xxxxxxxxxxxxxxx says...

"Perplexed in Peoria" <jimmenegay@xxxxxxxxxxxxx> wrote in message
news:E4Fei.15995$RX.14348@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx

"John Harshman" <jharshman.diespamdie@xxxxxxxxxxx> wrote in message
news:ZlEei.17405$y_7.7509@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
dkomo wrote:

I ran across some estimates of the prevalence of life in the universe.
There are 300 billion stars in an average galaxy and 100 billion
galaxies in the observable universe so the total number of stars is
10^21.

1. Harvard astronomer Harlow Shapely assumed:

a. 1 star in a thousand has planets
b. 1 in a thousand of the stars in (a) has a planet at the right
distance from it
c. 1 in a thousand of the planets in (b) is large enough to hold an
atmosphere
d. 1 in a thousand of the planets in (c) has the right chemical
composition to support life

and concluded there should be at least 100 million planets capable of
supporting life in the universe.

2. Astronomer Su-Shu Huang made less limiting assumptions, so that he
came to the conclusion that 5 percent of all solar systems in the
universe should be able to support life. This means 100 billion
life-bearing planets.

3. Harrison Brown assumed that almost every visible star posses a
partially or wholly invisible panetary system. This means 100 billion
solar systems in our own galaxy alone, and there are 100 billion
galaxies in this universe.

4. Frank Drake, the originator of the Drake equation, estimated that
10,000 advanced technological civilizations are likely to exist in the
Milky Way galaxy alone.

5. The Drake equation was updated and elaborated by Carl Sagan and
colleagues. They estimated that up to one million intelligent
civilizations could exist in our galaxy.

6. Robert Taormina applied the equations in (5) to a region within 100
light-years fro earth and found that more than 8 such civilizations
should be present within hailing distance from us.

The estimates of the number of life bearing planets or intelligent
civilizations vary quite a lot, but they are all significantly greater
than 1.

Do you think that a one of them is worth anything, or that input numbers
are any better than you could pull out of your ass? Consider the number
of intelligent civilizations we actually know about. Most estimates put
the number at either one or zero.

Earth has had a level of biological and ecological complexity capable of
supporting intelligent life for the past 250 million years, but we have
only had an intelligent species on this planet for the past 100K years
and a civilization capable of responding to a hail from somewhere in the
neighborhood for about 100 years. The chances that Earth will still
have an intelligent lifeform 100K years from now strike me as very
remote.

There is a term 'l' in the Drake equation for the average lifetime of
an intelligent species/civilization. If you assume that intelligent
species have about the same lifetime as any other species, those
optimistic estimates of the number of extant civilizations seem pretty
damned unlikely. Of course, if you assume that an intelligent
civilization
wouldn't do anything so stupid as to destroy its own biosphere, than
I have to go with John's lower estimate. We don't know about any
intelligent civilizations.

I disagree. I question whether there is ANY intelligent life at all on
Earth. lol

George <beam me up Scotty>

I think there is intelligent life on earth, it's just not very wise. =(
--
Steve "Chris" Price
Associate Professor of Computational Aesthetics
Amish Chair of Electrical Engineering
University of Ediacara "A fine tradition since 630,000,000 BC"

.

Relevant Pages

  • Re: Estimates of life in the universe
    ... There are 300 billion stars in an average galaxy and 100 billion ... star in a thousand has planets ... supporting life in the universe. ... civilizations could exist in our galaxy. ...
    (talk.origins)
  • Re: Estimates of life in the universe
    ... There are 300 billion stars in an average galaxy and 100 billion ... star in a thousand has planets ... supporting life in the universe. ... civilizations could exist in our galaxy. ...
    (talk.origins)
  • Re: Finally, NASA launches an ASTRONOMY satellite
    ... The universe is supposedly incredibly old- if you believe scientists/ ... Kepler contains a special telescope that will stare at 100,000 stars ... "The density of these planets has been astounding," Borucki said. ...
    (sci.astro.amateur)
  • Re: Estimates of life in the universe
    ... There are 300 billion stars in an average galaxy and 100 billion galaxies in the observable universe so the total number of stars is 10^21. ... 1 in a thousand of the planets in is large enough to hold an atmosphere ... and concluded there should be at least 100 million planets capable of supporting life in the universe. ...
    (talk.origins)
  • Re: Estimates of life in the universe
    ... There are 300 billion stars in an average galaxy and 100 billion ... star in a thousand has planets ... civilizations could exist in our galaxy. ...
    (talk.origins)
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