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ATKINSON FACULTY OF LIBERAL AND PROFESSIONAL STUDIES
SCHOOL OF ANALYTIC STUDIES & INFORMATION TECHNOLOGY
S C I E N C E A N D T E C H N O L O G Y S T U D I E S
NATS 1800 6.0 SCIENCE AND EVERYDAY PHENOMENA
Lecture 6: Is There Life on Earth?
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Readings, Resources and Questions
[*] The corresponding link is broken.
A very interesting and insightful book you should consider reading is L Margulis and D Sagan, What is Life?
(U of California Press, 1995, 2000).
Visit Is There Anybody Out There? , an
excellent collection of clear and accessible articles on the search for extraterrestrial life. Visit also
Astrobiology: The Search for Life,
part of Exploratorium: The Museum of Science, Art and Human Perception.
Another obligatory stop is NASA's Astrobiology.
"Astrobiology is the study of the origins, evolution, distribution, and future of life in the universe.
It requires fundamental concepts of life and habitable environments that will help us to recognize biospheres
that might be quite different from our own." [ from Astrobiology and the Roadmap ]
Scientists have tried to formulate educated guesses as to the likelihood of finding (intelligent) life in the
universe. The first, and perhaps most famous of such attempts was the work of Frank Drake.
"How can we estimate the number of technological civilizations that might exist among the stars? While working
as a radio astronomer at the National Radio Astronomy Observatory in Green Bank, West Virginia, Dr Frank Drake
(now Chairman of the Board of the SETI Institute) conceived an approach to bound the terms involved in estimating
the number of technological civilizations that may exist in our galaxy. The Drake Equation, as it has become known,
was first presented by Drake in 1961 and identifies specific factors thought to play a role in the development
of such civilizations. Although there is no unique solution to this equation, it is a generally accepted tool
used by the scientific community to examine these factors." [ from Drake Equation ]
Here is the Drake Equation:
N = R* x fp x ne x fl x fi x fc x L
N = the number of civilizations in The Milky Way Galaxy whose electromagnetic emissions are detectable.
You can try your hand at calculating N using PBS' On-line Calculator,
where current estimates of these parameters, and the difficulties in calculating such estimates, are briefly discussed.
Notice that some of these parameters (e.g. fc) are very hard to even guess. However,
"besides illuminating the factors involved in such a search, the Drake Equation is a simple, effective tool for
stimulating intellectual curiosity about the universe around us, for helping us to understand that life as we know it
is the end product of a natural, cosmic evolution, and for making us realize how much we are a part of that universe."
R* = the rate of formation of stars suitable for the development of intelligent life.
fp = the fraction of those stars with planetary systems.
ne = the number of planets, per solar system, with an environment suitable for life.
fl = the fraction of suitable planets on which life actually appears.
fi = the fraction of life bearing planets on which intelligent life emerges.
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space.
L = the length of time such civilizations release detectable signals into space.
Life is not the only complex system for which a definition still eludes us. Can you think
of other complex systems for which this is also true?