Carl Sagan, Believer
On his birthday, November 9, Carl Sagan fans should remember that he once said about the growth of scientific understanding: “It’s never been, `Oh, gee, this is nothing like what I had imagined. Just the opposite: It’s exactly like I imagined.” They would also do well to remember that the celebrated science popularizer not only imagined that intelligent life in space was abundant; he demonstrated it mathematically before the American Rocket Society in 1962.
Here’s the relevant report from Stars and Stripes, the American military newspaper,from: November 26, 1962
“Prof Says Beings From Outer Space Visited Earth,”
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 equals 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 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 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 a
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 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 is 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 so. “Asked if he believed in flying saucers, he said: “I do believe there are objects which have not been identified.”
[end of Stars and Stripes report]
It could be argued that Professor Sagan later became embarrassed by his early equations about life in space or, as one science fiction show had it, that the secret government alien interface group MJ12 bought him off and got him to keep quiet. Sagan later underscored his real concern about others who still might add it up the way he did in 1962: information overload, bane of the acid head. “If you are awash in lost continents and channeling and UFOs and all the long litany of claims so well exposed,” he remarked to Skeptical Inquirer magazine in 1998, “you may not have the intellectual room for the findings of science.” Somehow, of course, he found room. Happy birthday, Carl Sagan, wherever you are!
Related posts:
- White House: There’s no sign of E.T. or UFO cover-up
- Planets can survive a star’s supernova
- Here be aliens? New signs point to a billion planets in our own galaxy where extra-terrestrials might be
- Scientists think solar system may have had a FIFTH gas planet
- Scientists find fifty new planets… and one of them could have alien life
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