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Except in pure mathematics, nothing is known for certain (although much is certainly false).

Carl Sagan

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Carl Sagan
Age: 62 †
Born: 1934
Born: November 9
Died: 1996
Died: December 20
Astronomer
Astrophysicist
Cosmologist
Naturalist
Non-Fiction Writer
Novelist
Physicist
Planetary Scientist
Science Communicator
Brooklyn
New York
Carl Edward Sagan
Sagan
Carl E. Sagan
Carl E Sagan
C. E. Sagan
C.E. Sagan
C E Sagan
C. Sagan
C Sagan
Sagan C
Sagan C.
Sagan C. E.
Sagan CE
Mathematics
Except
Certainly
Pure
Known
Certain
Nothing
False
Much
Although

More quotes by Carl Sagan

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If chimpanzees have consciousness, if they are capable of abstractions, do they not have what until now has been described as 'human rights'? How smart does a chimp have to be before killing him constitutes murder?
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Because men, compared to male chimps, have such relatively small testicles (large testicles indicate a species where many males mate, one after the other, with the same female), we might guess that promiscuous societies were uncommon in the immediate human past.
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The suppression of uncomfortable ideas may be common in religion or in politics, but it is not the path to knowledge it has no in the endeavor of science. We do not know in advance who will discover fundamental insights.
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The wind whips through the canyons of the American Southwest, and there is no one to hear it but us - a reminder of the 40,000 generations of thinking men and women who preceded us, about whom we know almost nothing, upon whom our civilization is based.
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Extraordinary claim requires extraordinary proof.
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The dumbing down of America is evident in the slow decay of substantive content, a kind of celebration of ignorance.
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Better the hard truth, I say, than the comforting fantasy. And in the final tolling it often turns out that the facts are more comforting than the fantasy.
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But nature is always more subtle, more intricate, more elegant than what we are able to imagine.
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Is mankind alone in the universe? Or are there somewhere other intelligent beings looking up into their night sky from very different worlds and asking the same kind of question?
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We can always take but never give.
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Perhaps the depth of love can be calibrated by the number of different selves that are actively involved in a given relationship.
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There is much that science doesn't understand, many mysteries still to be resolved. In a Universe tens of billions of light-years across and some ten or fifteen billion years old, this may be the case forever. We are constantly stumbling on new surprises
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Somewhere, something incredible is waiting to be known.
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If the press descended, the science would surely suffer.
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It's perilous and foolhardy for the average citizen to remain ignorant about global warming, say, or ozone depletion, air pollution, toxic and radioactive wastes, acid rain, topsoil erosion, tropical deforestation, exponential population growth. Jobs and wages depend on science and technology.
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Every star may be a sun to someone.
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A tiny blue dot set in a sunbeam. Here it is. That's where we live. That's home. We humans are one species and this is our world. It is our responsibility to cherish it. Of all the worlds in our solar system, the only one so far as we know, graced by life.
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Any civilization that doesn't develop space travel dies.
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There are as many atoms in one molecule of DNA as there are stars in a typical galaxy.
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Science is not perfect. It's often misused it's only a tool, but it's the best tool we have. Self-correcting , ever changing, applicable to everything: with this tool, we vanquish the impossible.
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