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Carl Sagan Quotes
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Carl Edward Sagan was an American astronomer, cosmologist, astrophysicist, astrobiologist, author, science popularizer, and science communicator in astronomy and other natural sciences. He is best known as a science popularizer and communicator. His best known scientific contribution is research on extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation. Sagan assembled the first physical messages sent into space: the Pioneer plaque and the Voyager Golden Record, universal messages that could potentially be understood by any extraterrestrial intelligence that might find them. Sagan argued the now accepted hypothesis that the high surface temperatures of Venus can be attributed to and calculated using the greenhouse effect.Sagan published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books. He wrote many popular science books, such as The Dragons of Eden, Broca's Brain and Pale Blue Dot, and narrated and co-wrote the award-winning 1980 television series Cosmos: A Personal Voyage. The most widely-watched series in the history of American public television, Cosmos has been seen by at least 500 million people across 60 different countries. The book Cosmos was published to accompany the series. He also wrote the science fiction novel Contact, the basis for a 1997 film of the same name. His papers, containing 595,000 items, are archived at The Library of Congress.Sagan advocated scientific skeptical inquiry and the scientific method, pioneered exobiology and promoted the Search for Extra-Terrestrial Intelligence . He spent most of his career as a professor of astronomy at Cornell University, where he directed the Laboratory for Planetary Studies. Sagan and his works received numerous awards and honors, including the NASA Distinguished Public Service Medal, the National Academy of Sciences Public Welfare Medal, the Pulitzer Prize for General Non-Fiction for his book The Dragons of Eden, and, regarding Cosmos: A Personal Voyage, two Emmy Awards, the Peabody Award, and the Hugo Award. He married three times and had five children. After suffering from myelodysplasia, Sagan died of pneumonia at the age of 62, on December 20, 1996. Wikipedia  

✵ 9. November 1934 – 20. December 1996   •   Other names Karl Seýgan
Carl Sagan photo
Carl Sagan: 365   quotes 50   likes

Carl Sagan Quotes

“In fact, the thickness of the Earth's atmosphere, compared with the size of the Earth, is in about the same ratio as the thickness of a coat of shellac on a schoolroom globe is to the diameter of the globe. That's the air that nurtures us and almost all other life on Earth, that protects us from deadly ultraviolet light from the sun, that through the greenhouse effect brings the surface temperature above the freezing point. (Without the greenhouse effect, the entire Earth would plunge below the freezing point of water and we'd all be dead.) Now that atmosphere, so thin and fragile, is under assault by our technology. We are pumping all kinds of stuff into it. You know about the concern that chlorofluorocarbons are depleting the ozone layer; and that carbon dioxide and methane and other greenhouse gases are producing global warming, a steady trend amidst fluctuations produced by volcanic eruptions and other sources. Who knows what other challenges we are posing to this vulnerable layer of air that we haven't been wise enough to foresee?”

Carl Sagan

In Wonder and Skepticism, Skeptical Enquirer (Jan-Feb 1995), 19, No. 1.

Life , Light , Water , Sun

“Because it is clear from the fossil record that almost every species that has ever existed is extinct; extinction is the rule, survival is the exception.”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

“We have heard the rationales offered by the nuclear superpowers. We know who speaks for the nations. But who speaks for the human species? Who speaks for Earth?”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 329

“Superstition is marked not by its pretension to a body of knowledge but by its method of seeking truth.”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

Truth , Knowledge

“If we crave some cosmic purpose, then let us find ourselves a worthy goal.”

Carl Sagan book Pale Blue Dot

Pale Blue Dot: A Vision of the Human Future in Space (1994)

“There is no question that religions have historically played the role of making people contented with their lot. …such a doctrine would be very appealing to the ruling classes of a society. …Many societies, for this reason alone, encourage the contentment with your lot that the religious premise of heaven affords.”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

People , Religion , Question

“Modern science has been a voyage into the unknown, with a lesson in humility waiting at every stop. Many passengers would rather have stayed home.”

Carl Sagan book Pale Blue Dot

Pale Blue Dot: A Vision of the Human Future in Space (1994)

Home , Science , Waiting

“If a Creator God exists, would He or She or It… prefer a kind of sodden blockhead who worships while understanding nothing? Or would He prefer His votaries to admire the real universe in all its intracacy?”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

God , Understanding , Universe

“The idea that as I walk in this direction my watch goes slightly slower and I am contracted in the direction of motion and my mass has increased slightly does not correspond to everyday experience. …the reason that it does not correspond to common sense is that we are not in the habit of traveling close to the speed of light. We may one day be in that habit, and then the Lorentz transformations will be natural, intuitive.”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

Travel , Idea , Nature , Sense

“This planet is run by crazy people. Remember what they have to do to get where they are. Their perspective is so narrow, so…brief. A few years. In the best of them a few decades. They care only about the time they are in power.”

Carl Sagan book Contact

Source: Contact (1985), Chapter 23 (p. 403)

People , Time

“Do we, holding that the gods exist,
deceive ourselves with insubstantial dreams
and lies, while random careless chance and
change alone control the world?”

Carl Sagan book Contact

Source: Contact (1985), Chapter 10 (p. 157, quoting Euripides)

God , World , Dreams , Change

“Let's go back to the solar nebula… with the temperature declining the farther we get from the Sun. …at different distances from the Sun, different materials will condense out, because they have different vapor pressures or different melting points. …water condenses out roughly at the vicinity of the Earth, whereas silicates condense out closer to the Sun… you have to go out to somewhere near the present distance of Saturn before methane condenses.”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

Water , Sun

“Think of how many religions attempt to validate themselves with prophecy. Think of how many people rely on these prophecies, however vague, however unfulfilled, to support or prop up their beliefs. Yet has there ever been a religion with the prophetic accuracy and reliability of science? … No other human institution comes close.”

Carl Sagan

Source: The Demon-Haunted World : Science as a Candle in the Dark (1995), Ch. 2 : Science and Hope, p. 30

People , Religion , Support , Thinking

“I have a foreboding of an America in my children's or grandchildren's time -- when the United States is a service and information economy; when nearly all the manufacturing industries have slipped away to other countries; when awesome technological powers are in the hands of a very few, and no one representing the public interest can even grasp the issues; when the people have lost the ability to set their own agendas or knowledgeably question those in authority; when, clutching our crystals and nervously consulting our horoscopes, our critical faculties in decline, unable to distinguish between what feels good and what's true, we slide, almost without noticing, back into superstition and darkness.”

Carl Sagan

Source: The Demon-Haunted World : Science as a Candle in the Dark (1995), Ch. 2 : Science and Hope, p. 25

Children , People , Feeling , Question

“The neurochemistry of the brain is astonishingly busy, the circuitry of a machine more wonderful than any devised by humans. But there is no evidence that its functioning is due to anything more than the 1014 neural connections that build an elegant architecture of consciousness.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 278

Business

“We can’t just conclude that science puts too much power into the hands of morally feeble technologists or corrupt, power-crazed politicians and decide to get rid of it. Advances in medicine and agriculture have saved more lives than have been lost in all the wars in history. Advances in transportation, communication, and entertainment have transformed the world. The sword of science is double-edged.”

Carl Sagan

"Why We Need To Understand Science" in The Skeptical Inquirer Vol. 14, Issue 3 (Spring 1990)
Context: I know that science and technology are not just cornucopias pouring good deeds out into the world. Scientists not only conceived nuclear weapons; they also took political leaders by the lapels, arguing that their nation — whichever it happened to be — had to have one first. … There’s a reason people are nervous about science and technology.
And so the image of the mad scientist haunts our world—from Dr. Faust to Dr. Frankenstein to Dr. Strangelove to the white-coated loonies of Saturday morning children’s television. (All this doesn’t inspire budding scientists.) But there’s no way back. We can’t just conclude that science puts too much power into the hands of morally feeble technologists or corrupt, power-crazed politicians and decide to get rid of it. Advances in medicine and agriculture have saved more lives than have been lost in all the wars in history. Advances in transportation, communication, and entertainment have transformed the world. The sword of science is double-edged. Rather, its awesome power forces on all of us, including politicians, a new responsibility — more attention to the long-term consequences of technology, a global and transgenerational perspective, an incentive to avoid easy appeals to nationalism and chauvinism. Mistakes are becoming too expensive.

War , World , History , Communication

“Eratosthenes was the director of the great library of Alexandria, the Centre of science and learning in the ancient world. Aristotle had argued that humanity was divided into Greeks and everybody else, whom he called barbarians and that the Greeks should keep themselves racially pure. He thought it was fitting for the Greeks to enslave other peoples. But Eratosthenes criticized Aristotle for his blind chauvinism, he believed there was good and bad in every nation.”

Carl Sagan

25 Min 10 Sec
Cosmos: A Personal Voyage (1990 Update), Who Speaks for Earth? [Episode 13]

People , World , Learning , Science

“Imagine we could accelerate continuously at 1 g — what we're comfortable with on good old terra firma — to the midpoint of our voyage, and decelerate continuously at 1 g until we arrive at our destination. It would take a day to get to Mars, a week and a half to Pluto, a year to the Oort Cloud, and a few years to the nearest stars.”

Carl Sagan book Pale Blue Dot

Source: Pale Blue Dot: A Vision of the Human Future in Space (1994), p. 395

Imagination , Star

“It is easy to create an interstellar radio message which can be recognized as emanating unambiguously from intelligent beings. A modulated signal (‘beep,’ ‘beep-beep,’. . . ) comprising the numbers 1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, for example, consists exclusively of the first 12 prime numbers—that is, numbers that can be divided only by 1, or by themselves. A signal of this kind, based on a simple mathematical concept, could only have a biological origin.. . . But by far the most promising method is to send pictures.”

Carl Sagan

Smithsonian magazine, May 1978, pp. 43, 44. Quoted in Awake! magazine, 1978, 8/22.

Intelligence , Mathematics

“Humans are very good at dreaming, although you’d never know it from your television.”

Carl Sagan book Contact

Source: Contact (1985), Chapter 20 (p. 359)

Dreams

“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.”

Carl Sagan

As quoted in "Scientists & Their Gods" in U.S. News & World Report Vol. 111 (1991)

God , Law , Idea , Sense

“A general problem with much of Western theology… is that the God portrayed is too small. It is a god of a tiny world and not a god of a galaxy, much less a universe.”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

God , World , Problem , Universe

“That kind of skeptical, questioning, "don't accept what authority tells you" attitude of science — is also nearly identical to the attitude of mind necessary for a functioning democracy. Science and democracy have very consonant values and approaches, and I don't think you can have one without the other.”

Carl Sagan

Talk of the Nation (3 May 1996)

Democracy , Question , Thinking , Science

“The cosmic calendar compresses the local history of the universe into a single year. If the universe began on January 1st it was not until May that the Milky Way formed. Other planetary systems may have appeared in June, July and August, but our Sun and Earth not until mid-September. Life arose soon after.”

Carl Sagan

56 min 20 sec
Cosmos: A Personal Voyage (1990 Update), The Shores of the Cosmic Ocean [Episode 1]

Life , Way , History , Universe

“I have…a terrible need…shall I say the word?…of religion. Then I go out at night and paint the stars.”

Carl Sagan book Cosmos

Quoting Vincent van Gogh, p. 217
Cosmos (1980)

Religion , Star , Painting , Night

“This image of four spectra is taken from one of Huggins's publications. …You can see that the Comet Winnecke resembles olive oil more than it does Comet Brorsen.”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

“History is full of people who out of fear or ignorance or the lust for power have destroyed treasures of immeasurable value which truly belong to all of us. We must not let it happen again.”

Carl Sagan

36 min 20 sec
Cosmos: A Personal Voyage (1990 Update), Who Speaks for Earth? [Episode 13]

People , Fear , History

“As the ancient myth makers knew we're children equally of the earth and the sky. In our tenure on this planet we've accumulated dangerous evolutionary baggage, propensities for aggression and ritual, submission to leaders, hostility to outsiders, all of which puts our survival in some doubt. But we've also acquired compassion for others, love for our children, a desire to learn from history and experience and a great soaring passionate intelligence, the clear tools for our continued survival and prosperity. Which aspects of our nature will prevail is uncertain, particularly when our visions and prospects are bound to one small part of the small planet Earth. But up there in the Cosmos an inescapable perspective awaits.”

Carl Sagan

6 min 10 sec
Cosmos: A Personal Voyage (1990 Update), Who Speaks for Earth? [Episode 13]
Context: Unlike the La Pérouse expedition the Conquistadors sought not knowledge but Gold. They used their superior weapons to loot and murder, in their madness they obliterated a civilisation. In the name of piety, in a mockery of their religion, the Spaniards utterly destroyed a society with an Art, Astronomy and Architecture the equal of anything in Europe. We revile the Conquistadors for their cruelty and shortsightedness, for choosing death. We admire La Pérouse and the Tlingit for their courage and wisdom, for choosing life. The choice is with us still, but the civilisation now in jeopardy is all humanity. As the ancient myth makers knew we're children equally of the earth and the sky. In our tenure on this planet we've accumulated dangerous evolutionary baggage, propensities for aggression and ritual, submission to leaders, hostility to outsiders, all of which puts our survival in some doubt. But we've also acquired compassion for others, love for our children, a desire to learn from history and experience and a great soaring passionate intelligence, the clear tools for our continued survival and prosperity. Which aspects of our nature will prevail is uncertain, particularly when our visions and prospects are bound to one small part of the small planet Earth. But up there in the Cosmos an inescapable perspective awaits. National boundaries are not evident when we view the Earth from space. Fanatical ethnic or religious or national identifications are a little difficult to support when we see our Earth as a fragile blue crescent fading to become an inconspicuous point of light against the bastion and the citadel of the stars. There are not yet obvious signs of extraterrestrial intelligence and this makes us wonder whether civilisations like ours rush inevitably headlong into self-destruction.

Love , Hostility , Children , History

“There is no other species on the Earth that does science. It is, so far, entirely a human invention, evolved by natural selection in the cerebral cortex for one simple reason: it works. It is not perfect. It can be misused. It is only a tool. But it is by far the best tool we have, self-correcting, ongoing, applicable to everything. It has two rules. First: there are no sacred truths; all assumptions must be critically examined; arguments from authority are worthless. Second: whatever is inconsistent with the facts must be discarded or revised. We must understand the Cosmos as it is and not confuse how it is with how we wish it to be.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 333

Truth , Understanding , Nature , Science

“Who is more humble? The scientist who looks at the universe with an open mind and accepts whatever it has to teach us, or somebody who says everything in this book must be considered the literal truth and never mind the fallibility of all the human beings involved?”

Carl Sagan

Charlie Rose: An Interview with Carl Sagan http://www.charlierose.com/guest/view/4553, May 27, 1996.

Truth , Books , Universe

“The prediction I can make with the highest confidence is that the most amazing discoveries will be the ones we are not today wise enough to foresee.”

Carl Sagan

Cited in Tim Flannery, Atmosphere of Hope. Solutions to the Climate Crisis, Penguin Books, 2015, pages 162 ISBN 9780141981048.
Others

Confidence

“Those who are skeptical about carbon dioxide greenhouse warming might profitably note the massive greenhouse effect on Venus. No one proposes that Venus's greenhouse effect derives from imprudent Venusians who burned too much coal, drove fuel-inefficient autos, and cut down their forests. My point is different. The climatological history of our planetary neighbor, an otherwise Earthlike planet on which the surface became hot enough to melt tin or lead, is worth considering — especially by those who say that the increasing greenhouse effect on Earth will be self-correcting, that we don't really have to worry about it, or (you can see this in the publications of some groups that call themselves conservative) that the greenhouse effect is a "hoax."”

Carl Sagan book Pale Blue Dot

Source: Pale Blue Dot: A Vision of the Human Future in Space (1994), p. 227

History

“I think people in power have a vested interest to oppose critical thinking.”

Carl Sagan

http://www.sciencefriday.com/segments/carl-sagan-science-is-a-way-of-thinking/
Carl Sagan: 'Science Is a Way of Thinking', Science Friday interview from May 1996
27 December 2013

People , Thinking

“Suppose your father… walked into this room at the ordinary human pace of walking. And suppose just behind him was his father. How long would we have to wait before the ancestor who enters the now-open door is a creature who normally walked on all fours? The answer is a week.”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

Waiting

“In science it often happens that scientists say, "You know that's a really good argument; my position is mistaken," and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion.”

Carl Sagan

Keynote address at CSICOP conference (1987), as quoted in Do Science and the Bible Conflict? (2003) by Judson Poling, p. 30

Pain , Religion , Science , Change

“There is a place with four suns in the sky — red, white, blue, and yellow; two of them are so close together that they touch, and star-stuff flows between them. I know of a world with a million moons. I know of a sun the size of the Earth — and made of diamond. There are atomic nuclei a few miles across which rotate thirty times a second. There are tiny grains between the stars, with the size and atomic composition of bacteria. There are stars leaving the Milky Way, and immense gas clouds falling into it. There are turbulent plasmas writhing with X- and gamma-rays and mighty stellar explosions. There are, perhaps, places which are outside our universe. The universe is vast and awesome, and for the first time we are becoming a part of it.”

Carl Sagan

Planetary Exploration (University of Oregon Books, Eugene, Oregon, 1970), page 15

World , Way , Star , Universe

“Education on the value of free speech and the other freedoms reserved by the Bill of Rights, about what happens when you don't have them, and about how to exercise and protect them, should be an essential prerequisite for being an American citizen — or indeed a citizen of any nation, the more so to the degree that such rights remain unprotected. If we can't think for ourselves, if we're unwilling to question authority, then we're just putty in the hands of those in power. But if the citizens are educated and form their own opinions, then those in power work for us. In every country, we should be teaching our children the scientific method and the reasons for a Bill of Rights. With it comes a certain decency, humility and community spirit. In the demon-haunted world that we inhabit by virtue of being human, this may be all that stands between us and the enveloping darkness.”

Carl Sagan

Source: The Demon-Haunted World : Science as a Candle in the Dark (1995), Ch. 25 : Real Patriots Ask Questions

Children , World , Education , Exercises

“A googolplex is precisely as far from infinity as is the number 1… no matter what number you have in mind, infinity is larger still.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 220

“Jingoistic rhetoric and puerile self-congratulatory nationalism.”

Carl Sagan book Contact

Source: Contact (1985), Chapter 11 (p. 181)

“You see, the religious people — most of them — really think this planet is an experiment. That’s what their beliefs come down to. Some god or other is always fixing and poking, messing around with tradesmen’s wives, giving tablets on mountains, commanding you to mutilate your children, telling people what words they can say and what words they can’t say, making people feel guilty about enjoying themselves, and like that. Why can’t the gods leave well enough alone? All this intervention speaks of incompetence. If God didn’t want Lot’s wife to look back, why didn’t he make her obedient, so she’d do what her husband told her? Or if he hadn’t made Lot such a shithead, maybe she would’ve listened to him more. If God is omnipotent and omniscient, why didn’t he start the universe out in the first place so it would come out the way he wants? Why’s he constantly repairing and complaining? No, there’s one thing the Bible makes clear: The biblical God is a sloppy manufacturer. He’s not good at design, he’s not good at execution. He’d be out of business if there was any competition.”

Carl Sagan book Contact

Source: Contact (1985), Chapter 16 (p. 285)

God , Children , People , Way

“The Platonists and their Christian successors held the peculiar notion that the Earth was tainted and somehow nasty, while the heavens were perfect and divine. The fundamental idea that the Earth is a planet, that we are citizens of the Universe, was rejected and forgotten.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 188

Idea , Universe , Perfection

“Human beings have a demonstrated talent for self-deception when their emotions are stirred.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 135

“I wish to propose a doctrine which may, I fear, appear wildly paradoxical and subversive. The doctrine in question is this: that it is undesirable to believe a proposition when there is no ground whatever for supposing it true. I must, of course, admit that if such an opinion became common it would completely transform our social life and our political system; since both are at present faultless, this must weigh against it.”

Carl Sagan book Contact

Source: Contact (1985), Chapter 2 (p. 15, quoting Bertrand Russell)

Life , Fear , Question , Appearance

“If a marker were to be erected today, it might read, in homage to his scientific courage: “He preferred the hard truth to his dearest illusions.””

Carl Sagan book Cosmos

On the character of Johannes Kepler, p. 67
Cosmos (1980)

Truth , Courage , Reading

“At birth all of us imagine that we are the universe, and we don't distinguish the boundaries between ourselves and those around us. …in some social situations, there is the sense that we are central, important. …there was a natural projection of those attitudes upon the universe.”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

Imagination , Birth , Nature , Sense

“Something dreadful happens to students between first and twelfth grades, and it's not just puberty.”

Carl Sagan

http://www.sciencefriday.com/segments/carl-sagan-science-is-a-way-of-thinking/
Carl Sagan: 'Science Is a Way of Thinking', Science Friday interview from May 1996
27 December 2013

“A central lesson of science is that to understand complex issues (or even simple ones), we must try to free our minds of dogma and to guarantee the freedom to publish, to contradict, and to experiment. Arguments from authority are unacceptable.”

Carl Sagan

Source: Billions and Billions: Thoughts on Life and Death at the Brink of the Millenium (1997), Chapter 14, "The Common Enemy".

Understanding , Freedom , Science

“Relativity does set limits on what humans can ultimately do. But the universe is not required to be in perfect harmony with human aspirations.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 201

Universe , Perfection

“Humans may crave absolute certainty; they may aspire to it; they may pretend, as partisans of certain religions do, to have attained it. But the history of science — by far the most successful claim to knowledge accessible to humans — teaches that the most we can hope for is successive improvement in our understanding, learning from our mistakes, an asymptotic approach to the Universe, but with the proviso that absolute certainty will always elude us.”

Carl Sagan

Source: The Demon-Haunted World : Science as a Candle in the Dark (1995), Ch. 2 : Science and Hope, p. 28

Religion , Hope , History , Understanding