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- From: thad@netcom.com (Thad Floryan)
- Newsgroups: alt.alien.visitors,alt.paranet.ufo
- Subject: Sagan 30 years ago ...
- Message-ID: <thadC8GE4v.1sH@netcom.com>
- Date: 11 Jun 93 10:50:54 GMT
- Followup-To: alt.alien.visitors
- Organization: Personal account at Netcom Public Access UNIX
- Lines: 91
-
- As mentioned in the just-prior post, I finally found some of my long-mislaid
- UFO file material; while thumbing through some of the notebooks, the following
- item also caught my eye.
-
- Appearing in the _Stars and Stripes_ (a US Military newspaper), Monday,
- November 26, 1962 (yes, 30+ years ago):
-
- `` PROF SAYS BEINGS FROM OUTER SPACE HAVE VISITED EARTH
-
-
- Los Angeles (AP) -- Some of the best scientific minds in the country
- were stumped when a slender, dark-haired young man chalked on the
- blackboard this equation:
-
- N = R FP NE FL FI FC L
-
- The speaker was Dr. Carl Sagan, a 28-year-old assistant professor
- of astronomy at Harvard University.
-
- His audience consisted of several hundred members of the American
- Rocket Society, gathered for his luncheon address.
-
- The equation was his way of expressing the mathematical probability
- that intelligent beings from outer space have visited earth.
-
- Sagan soberly explained that in his equation `N' stands for the
- number of advanced technical civilizations in the universe possessing
- the capability of interstellar communication.
-
- `R' is the mean rate of star formation averaged over the lifetime of
- the galaxy.
-
- `FP' is the fraction of stars with planetary systems.
-
- `NE' is the mean number of planets in each system with environments
- favorable for the origin of life.
-
- `FL' is the fraction of such planets on which life does develop.
-
- `FI' is the fraction of such inhabited planets on which intelligent
- life with manipulative abilities rises during the lifetime of the
- local sun.
-
- `FC' is the fraction of planets populated by intelligent beings on
- which an advanced technical civilization rises.
-
- And `L' is the lifetime of this technical civilization.
-
- Sagan said information in his formula is based on current estimates
- by astronomers. In making calculations, he assigned each symbol an
- arbitrary numerical value.
-
- As expressed in numbers, Sagan said, the formula means that at least
- 1 million of the 100 billion stars in our Milky Way galaxy have planets
- which have developed civilizations capable of travel between the stars.
-
- "Let's say that each of these civilizations sends out one interstellar
- expedition per year," he said.
-
- "That means that every star, such as our sun, would be visited at least
- once every million years. In some systems where these beings found
- life, they would make more frequent visits. There's a strong
- probability, then, that they have visited earth every few thousand
- years.
-
- "It is not out of the question that artifacts of these visits still
- exist or even that some kind of base in maintained, possibly
- automatically, within the solar system, to provide continuity for
- successive expeditions.
-
- "Because of weathering and the possibility of detection and
- interference by the inhabitants of earth, it would be preferable not
- to erect such a base on the earth's surface. The moon seems one
- reasonable alternative.
-
- "Forthcoming photographic reconnaissance of the moon from space
- vehicles -- particularly of the back -- might bear these possibilities
- in mind."
-
- At a news conference, Sagan predicted man himself would be capable of
- interstellar flight at close to the speed of light "within a century
- or two."
-
- Asked if he believed in flying saucers, he said: "I do believe there
- are objects which have not been identified."
-
- ''
-
- {end of article}
-
- Thad Floryan [ thad@btr.com, thad@cup.portal.com, thad@netcom.com ]
-
-