article

Dr. Carl Edward Sagan (November 9 1934 – December 20 1996) was an American astronomer, astrobiologist, and highly successful science popularizer. He pioneered exobiology and promoted the Search for Extra-Terrestrial Intelligence (SETI). He is world-famous for writing popular science books and for co-writing and presenting the award-winning television series A Personal Voyage, the most-watched PBS program of all time According to nasa.gov, *. A book to accompany the program was also published. He also wrote the novel Contact, upon which the 1997 film of the same name starring Jodie Foster was based. In his works, he frequently advocated skepticism, humanism, and the scientific method.

Education and scientific career

Carl Sagan was born in Brooklyn, New YorkFor biographical information see A Life in the Cosmos by William Poundstone. Henry Holt & Company (October 1 1999) ISBN 0-805-05766-8. His parents were Jewish; his father, Sam Sagan, was a garment worker and his mother, Rachel Molly Gruber, was a housewife. Sagan attended the University of Chicago, where he received a bachelor's degree (1955) and a master's degree (1956) in physics, before earning his doctorate (1960) in astronomy and astrophysics. During his time as an undergraduate, Sagan spent some time working in the laboratory of the geneticist H. J. Muller. In the early 1960s, no one knew for certain the basic conditions of the surface of the planet Venus and Sagan listed the possibilities in a report (which were later depicted for popularization in a Time-Life book, Planets) — his own view was that the planet was dry and very hot, as opposed to the balmy paradise others had imagined. As a visiting scientist to NASA's Jet Propulsion Laboratory, he contributed to the first Mariner missions to Venus, working on the design and management of the project. Mariner 2 confirmed his views on the conditions of Venus in 1962.

Sagan taught at Harvard University until 1968, when he moved to Cornell University. He became a full professor at Cornell in 1971 and directed a lab there. He contributed to most of the unmanned space missions that explored the solar system. He conceived the idea of adding an unalterable and universal message on spacecraft destined to leave the solar system that could be understood by any extraterrestrial intelligence that might find it. Sagan assembled the first physical message that was sent into space: a gold-anodized plaque, attached to the space probe Pioneer 10, launched in 1972. Pioneer 11, also containing the plaque, was launched the following year. He continued to refine his designs and the most elaborate such message he helped to develop and assemble was the Voyager Golden Record that was sent out with the Voyager space probes in 1977.

Sagan taught at Cornell a course on critical thinking until the year of his death in 1996. The course had only a limited number of seats, although hundreds of students tried to attend. He chose about 20 students who were allowed to enroll by reading huge piles of application essays. The course was discontinued after his death.

Scientific achievements

Sagan was among the first to hypothesize that Saturn's moon TitanMuch of Sagan's research in the field of planetary science is outlined by William Poundstone (see reference #1, above). Poundstone's biography of Sagan includes an eight page list of Sagan's scientific articles published from 1957 to 1998. Detailed information about Sagan's scientific work comes from the primary research articles. Example: Sagan, C., Thompson, W. R., and Khare, B. N. A Laboratory for Prebiological Organic Chemistry, Accounts of Chemical Research, volume 25, page 286 (1992). There is commentary on this research article about Titan at The Encyclopedia of Astrobiology, Astronomy, and Spaceflight. and Jupiter's moon Europa may possess oceans (a subsurface ocean, in the case of Europa) or lakes, thus making the hypothesized water ocean on Europa potentially habitable for life. Europa's subsurface ocean was later indirectly confirmed by the spacecraft Galileo.

He furthered insights regarding the atmospheres of Venus and Jupiter as well as seasonal changes on Mars. Sagan established that the atmosphere of Venus is extremely hot and dense. He also perceived global warming as a growing, man-made danger and likened it to the natural development of Venus into a hot life-hostile planet through greenhouse gasses. Sagan speculated (along with his Cornell colleague E. E. Salpeter) about life in Jupiter's clouds, given the planet's dense atmospheric composition rich in organic molecules. He suggested that the seasonal changes on Mars were due to windblown dust, not to vegetation changes, as others had proposed.

Scientific advocacy

Sagan was a proponent of the search for extraterrestrial life. He urged the scientific community to listen with large radio telescopes for signals from intelligent extraterrestrial lifeforms. He advocated sending probes to other planets. Sagan was Editor in Chief of Icarus (a professional journal concerning planetary research) for 12 years. He cofounded the Planetary Society and was a member of the SETI Institute Board of Trustees. Sagan helped Dr. Frank Drake write the Arecibo message, a radio message beamed into space from the Arecibo radio telescope in 1974, aimed at informing extraterrestrials about Earth.

He was well known as a co-author of the scientific paper that predicted nuclear winterTurco RP, Toon OB, Ackerman TP, Pollack JB, Sagan C. an appraisal of nuclear winter, Science, volume 247, pages 166-176 (1990). PubMed abstract | JSTORE link to full text article. Carl Sagan discussed his involvement in the political nuclear winter debates and his erroneous global cooling prediction for the Gulf War fires in his book, The Demon-Haunted World. would follow nuclear war. Sagan famously predicted that smoky oil fires in Kuwait (set by Saddam Hussein's army) would cause an ecological disaster of black clouds. Retired atmospheric physicist Fred Singer dismissed Sagan's prediction as nonsense, predicting that the smoke would dissipate in a matter of days. In his book The Demon-Haunted World, Sagan gave a list of errors he had made (including his predictions about the effects of the Kuwaiti oil fires) as an example of how science is tentative.

Sagan is also known for being involved as a researcher in Project A119, a secret US Air Force operation whose purpose was to drop a bomb on Earth's Moon.

Social concerns

Sagan believed that the Drake equation suggested that a large number of extraterrestrial civilizations would form, but that the lack of evidence of such civilizations (the Fermi paradox) suggests that technological civilizations tend to destroy themselves rather quickly. This stimulated his interest in identifying and publicizing ways that humanity could destroy itself, with the hope of avoiding such destruction and eventually becoming a space-faring species. Sagan became more politically active after marrying novelist Ann Druyan, performing acts of civil disobedience at nuclear weapons sites during the Nuclear freeze era. He spoke out against President Ronald Reagan's Strategic Defense Initiative, or the "Star Wars" program, which he felt was technically impossible to build and perfect, far more expensive to create than for an enemy to defeat through decoys and other means, and destabilizing to Cold War nuclear weapons disarmament progress.

Carl Sagan used marijuana, although he never admitted this publicly during his life. Under the pseudonym "Mr. X," he wrote an essay concerning cannabis smoking in the 1971 book Marihuana Reconsidered, whose editor was Lester GrinspoonMarihuana Reconsidered by Lester, M.D. Grinspoon. Publisher: Quick American Archives (2nd edition; April 1 1994) ISBN 0932551130. Sagan's essay is available online.. In his essay, Sagan commented that marijuana encouraged some of his works and enhanced experiences. After Sagan's death, Grinspoon disclosed this to Sagan's biographer, Keay Davidson A Life by Keay Davidson. John Wiley & Sons (August 30 1999) ISBN 0471252867. When the biography, entitled Carl Sagan: A Life, was published in 1999, the marijuana exposure stirred some media attentionBBC news story that includes mention of Sagan's marijuana use..

Popularization of science

Sagan's capability to convey his ideas allowed many people to better understand the cosmos. He delivered the 1977/1978 Christmas Lectures for Young People at the Royal Institution. He narrated and, with Ann Druyan, co-wrote and co-produced the highly popular thirteen part PBS television series: A Personal Voyage (modeled on Jacob Bronowski's The Ascent of Man). Cosmos covered a wide range of scientific subjects including the origin of life and a perspective of our place in the universe. The series was first broadcast by the Public Broadcasting Service in 1980. It won an Emmy and a Peabody Award; according to the NASA Office of Space Science, it has been since broadcast in 60 countries and seen by more than 600 million people.

Sagan also wrote books to popularize science, such as Cosmos, which reflected and expanded upon some of the themes of A Personal Voyage, The Dragons of Eden: Speculations on the Evolution of Human Intelligence, which won a Pulitzer Prize, and Reflections on the Romance of Science. Sagan also wrote the best-selling science fiction novel Contact, but never lived to see the book's 1997 motion picture adaptation, which starred Jodie Foster and won the 1998 Hugo Award.

From Cosmos and his frequent appearances on The Tonight Show, Sagan became associated with the catch phrase, "billions and billions." (He never actually used that phrase in Cosmos, but his distinctive delivery and frequent use of billions made this a favorite phrase of Johnny Carson and others, doing many affectionate impressions of him. Sagan took this in good humor, and his final book was entitled Thoughts on Life and Death at the End of the Millennium - see below.) A humorous unit of measurement, the Sagan, has now been coined to stand for any count of at least 4,000,000,000.

He wrote a sequel to Cosmos, Pale Blue Dot: A Vision of the Human Future in Space, which was selected as a notable book of 1995 by The New York Times. Carl Sagan also wrote an introduction for the bestselling book by Stephen Hawking, A Brief History of Time.

Sagan presents a speculation concerning the origin of the swastika symbol in his book, Comet. Sagan hypothesized that a comet approached so close to Earth in antiquity that the jets of gas streaming out of it were visible, bent by the comet's rotation. The book Comet reproduces an ancient Chinese manuscript that shows comet tail varieties; most are variations on simple comet tails, but the last shows the comet nucleus with four bent arms extending from it, showing a swastika.

Sagan caused mixed reactions among other professional scientists. On the one hand, there was general support for his popularization of science, his efforts to increase scientific understanding among the general public, and his positions in favor of scientific skepticism and against pseudoscience; most notably his thorough debunking of the book Worlds in Collision by Immanuel Velikovsky. On the other hand, there was some unease that the public would misunderstand some of the personal positions and interests that Sagan took as being part of the scientific consensus, rather than his own personal views. Some believe this unease to have been motivated in part by professional jealousy, that scientific views contrary to those that Sagan took (such as on the severity of nuclear winter) were not being sufficiently presented to the public.

Sagan's arguments against Velikovsky's catastrophism have been criticized by some of his colleagues. Robert Jastrow of NASA's Goddard Institute for Space Studies wrote: "Professor Sagan's calculations, in effect, ignore the law of gravity. Here, Dr. Velikovsky was the better astronomer." His comments on the Kuwait oil well fires during the first Gulf War were shown later to be incorrect; Sagan himself acknowledged his error in print.

Late in his life, Sagan's books developed his skeptical, naturalistic view of the world. In The Demon-Haunted World: Science as a Candle in the Dark, he presented tools for testing arguments and detecting fallacious or fraudulent ones, essentially advocating wide use of the scientific method. The compilation, Thoughts on Life and Death at the End of the Millennium, published in 1998 after Sagan's death, contains essays written by Sagan, such as his views on abortion, and Ann Druyan's account of his death as a skeptic, atheist and free thinker.

In 2006, Ann Druyan edited Sagan's 1985 Gifford Lectures into a new book, Gifford Lectures in Natural Theology, The Varieties of Scientific Experience: A Personal View of the Search for God, in which he elaborates on his views of divinity in the natural world.

Personality

In 1966, Sagan was asked to contribute an interview about the possibility of extraterrestrials to a proposed introduction to the film A Space Odyssey (film). According to an uncited anecdote in The Independent, Sagan "responded by saying that he wanted editorial control and a percentage of the film's takings, which was rejected." 2001: The secrets of Kubrick's classic" by Anthony Barnes (23 October 2005).

In 1994, Apple Computer began developing the Power Macintosh 7100. They chose the internal code name "Carl Sagan," in honor of the astronomer.An account of this lawsuit is given in A Life in the Cosmos, pages 363-364 and 374-375. Though the project name was strictly internal and never used in public marketing, when Sagan learned of this internal usage, he sued Apple Computer to use a different project name — other projects had names like "Cold fusion" and "Piltdown Man", and he was displeased at being associated with what he considered pseudoscience. Though Sagan lost the suit, Apple engineers complied with his demands anyway, renaming the project "BHA" (Butt-Head Astronomer). Sagan sued Apple for libel over the new name, claiming that it subjected him to contempt and ridicule. Sagan lost this lawsuit as well; still, the 7100 saw another name change: it was lastly called "LAW" (Lawyers Are Wimps). Sagan is regarded by most as an atheist, agnostic, or pantheist observing statements such as: "The idea that God is an oversized white male with a flowing beard, who sits in the sky and tallies the fall of every sparrow is ludicrous. But if by 'God,' one means the set of physical laws that govern the universe, then clearly there is such a God. This God is emotionally unsatisfying... it does not make much sense to pray to the law of gravity."A similar quote can be found in Chapter 23 of Sagan's book Reflections on the Romance of Science. "Some people think God is an outsized, light-skinned male with a long white beard, sitting on a throne somewhere up there in the sky, busily tallying the fall of every sparrow. Others - for example Baruch Spinoza and Albert Einstein - considered God to be essentially the sum total of the physical laws which describe the universe. I do not know of any compelling evidence for anthropomorphic patriarchs controlling human destiny from some hidden celestial vantage point, but it would be madness to deny the existence of physical laws." Sagan was also widely considered as a freethinker or skeptic, one of his most famous quotations (as seen in Cosmos) being, "Extraordinary claims require extraordinary evidence."

Sagan married three times; the famous biologist, Lynn Margulis (mother of Dorion Sagan and Jeremy Sagan) in 1957, artist Linda Salzman (mother of Nick Sagan) in 1968, and author Ann Druyan (mother of Sasha and Sam) in 1981, to whom he remained married until his death.

Isaac Asimov described Sagan as one of the only two people he ever met who were just plain smarter than Asimov himself. The other was computer scientist Marvin Minsky.

Sagan and UFOs

Sagan had some interest in UFO reports from at least 1964, when he had several conversations on the subject with Jacques Vallee. (Westrum 37) Though quite skeptical of any extraordinary answer to the UFO question, Sagan thought that science should study the phenomenon, at least because there was widespread public interest in UFO reports.

Stuart Appelle notes that Sagan "wrote frequently on what he perceived as the logical and empirical fallacies regarding UFOs and the abduction experience. Sagan rejected an extraterrestrial explanation for the phenomenon but felt there were both empirical and pedagogical benefits for examining UFO reports and that the subject was, therefore, a legitimate topic of study." (Appelle 22)

In 1966, Sagan was a member of the Ad Hoc Committee to Review Project Blue Book. The committee concluded that the U.S. Air Force's Project Blue Book had been lacking as a scientific study, and recommended a university-based project to give the UFO phenomenon closer scientific scrutiny. The Condon Committee (1966-1968), lead by physicist Edward Condon, and their still-controversial final report, formally concluded that there was nothing anomalous about UFO reports.

Ron Westrum writes that "The high point of Sagan's treatment of the UFO question was the AAAS's symposium in 1969. A wide range of educated opinions on the subject were offered by participants, including not only proponents as James McDonald and J. Allen Hynek but also skeptics like astronomers William Hartmann and Donald Menzel. The roster of speakers was balanced, and it is to Sagan's credit that this event was presented in spite of pressure from Edward Condon." (Westrum 37-38) With physicist Thornton Page, Sagan edited the lectures and discussions given at the symposium; these were published in 1972 as UFO's: A Scientific Debate.

Jerome Clark writes that Sagan's perspective on UFO's irked Condon: "... though a skeptic, (Sagan) was too soft on UFOs for Condon's taste. In 1971, he considered blackballing Sagan from the prestigious Cosmos Club". (Clark 603)

Some of Sagan's many books examine UFOs (as did one episode of Cosmos) and he recognized a religious undercurrent to the phenomenon. However, Westrum writes that "Sagan spent very little time researching UFOs ... he thought that little evidence existed to show that the UFO phenomenon represented alien spacecraft and that the motivation for interpreting UFO observations as spacecraft was emotional." (Westrum 37)

It is sometimes noted that Sagan's generally skeptical attitude to UFOs conflicted sharply with his views in a 1966 book he wrote with Russian astronomer and astrophysicist I.S. Shklovskii, Intelligent Life in the Universe. Here Sagan instead argued that technologically advanced alien civilizations were common and he considered it very probable that Earth had been visited many times in the past.

Yet only a few years later in UFO's: A Scientific Debate, Sagan was now highly skeptical of interstellar visitation. As to the physical possibility of interstellar travel, Sagan brought up the proposed Bussard ramjet as an interstellar vehicle. While not terribly practical, Sagan thought such proposed propulsion systems were nevertheless important because they demonstrated that there were conceivable ways of accomplishing interstellar travel "without bumping into fundamental physical constraints. And this suggests that it is premature to say that interstellar space flight is out of the question." But to this Sagan added, "I believe the numbers work out in such a way that UFO's as interstellar vehicles is extremely unlikely, but I think it is an equally bad mistake to say that interstellar space flight is impossible."

Sagan revealed his views on interstellar travel in his 1980 Cosmos series. Although he scoffed at the idea that UFOs are visiting Earth, maintaining that the distance between stars was too great to make interstellar travel feasible for aliens,in another episode he said the stars would "beckon" to humanity, describing the Bussard ramjet as one way humans might achieve interstellar travel. Sagan pointed out that there is no evidence that aliens have actually visited the Earth, either in the past or present (Sagan, 1995: 81-96, 99-104).

Legacy

After a long and difficult fight with myelodysplasia, Sagan died at the age of 62, on December 20 1996, at the Fred Hutchinson Cancer Research Center in Seattle, Washington. Sagan was a significant figure, and his supporters credit his importance to his popularization of the natural sciences, opposing both restraints on science and reactionary applications of science, defending democratic traditions, resisting nationalism, defending humanism, and arguing against geocentric and anthropocentric views. The landing site of the unmanned Mars Pathfinder spacecraft was renamed the Carl Sagan Memorial Station on July 5 1997. Asteroid 2709 Sagan is also named in his honor.

The 1997 movie Contact (see above), based on Sagan's novel of the same name and finished after his death, ends with the dedication "For Carl."

On November 9, 2001, on what would have been Sagan’s 67th birthday, the NASA Ames Research Center dedicated the site for the Carl Sagan Center for the Study of Life in the Cosmos. "Carl was an incredible visionary, and now his legacy can be preserved and advanced by a 21st century research and education laboratory committed to enhancing our understanding of life in the universe and furthering the cause of space exploration for all time," said NASA Administrator Daniel Goldin.

In 2004, the electronic music group Sagan released the CD/DVD "Unseen Forces." The music was accompanied by a DVD which featured humorous music video format homages of many of the historical sketches from Cosmos.

In an episode of Enterprise entitled "Terra Prime", a quick shot is shown of the relic rover Sojourner, part of the Mars Pathfinder mission, placed by a historical marker at Carl Sagan Memorial Station on the Martian surface. The marker displays a quote from Sagan: "Whatever the reason you're on Mars, I'm glad you're there, and I wish I was with you."

Awards and medals

Related books and media

Footnotes

External links

1934 births | 1996 deaths | American astronomers | Planetary scientists | American humanists | Jewish American writers | Jewish-American scientists | Pulitzer Prize winners | Science fiction writers | Science writers | Agnostics | Skeptics | Cornell University faculty | University of Chicago alumni | Space visionaries

Карл Сейгън | Carl Sagan | Carl Sagan | Carl Sagan | Καρλ Σαγκάν | Carl Sagan | Carl Sagan | Carl Sagan | Carl Sagan | Carl Sagan | 칼 세이건 | Carl Sagan | Carl Sagan | Carl Sagan | קרל סייגן | Karlas Saganas | Carl Sagan | Carl Sagan | カール・セーガン | Carl Sagan | Carl Sagan | Carl Sagan | Саган, Карл | Carl Sagan | Carl Sagan | Carl Edward Sagan | Carl Sagan | Carl Sagan | คาร์ล เซแกน | Carl Sagan | 卡尔·萨根

 

This article is licensed under the GNU Free Documentation License. It uses material from the "Carl Sagan".

Home Page • arts • business • computers • games • health • hospitals • home • kids & teens • news • physicians • recreation• reference • regional • science • shopping • society • sports • world