The faint young Sun paradox or problem describes the apparent contradiction between observations of liquid water early in the Earth's history and the astrophysical expectation that the Sun's output would be only 70% as intense during that epoch as it is during the modern epoch. The issue was raised by astronomers Carl Sagan and George Mullen in 1972. Explanations of this paradox have taken into account greenhouse effects, astrophysical influences, or a combination of the two.
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Famous quotes containing the words faint, young, sun and/or paradox:
“I have a faint cold fear thrills through my veins,
That almost freezes up the heat of life.”
—William Shakespeare (1564–1616)
“There were those young men,
those village lands
and that youthfulness of mine.
People tell it
like a tale
that I must listen to.”
—Hla Stavhana (c. 50 A.D.)
“The angels all were singing out of tune,
And hoarse with having little else to do,
Excepting to wind up the sun and moon,
Or curb a runaway young star or two,”
—George Gordon Noel Byron (1788–1824)
“The conclusion suggested by these arguments might be called the paradox of theorizing. It asserts that if the terms and the general principles of a scientific theory serve their purpose, i. e., if they establish the definite connections among observable phenomena, then they can be dispensed with since any chain of laws and interpretive statements establishing such a connection should then be replaceable by a law which directly links observational antecedents to observational consequents.”
—C.G. (Carl Gustav)