a. The sun's temperature is right to
provide the range of light wavelengths suitable for life. Higher temperatures would result
in too much ultraviolet radiation, lower temperatures in too much infrared.
b. The sun is at the correct distance
from the earth and has the proper size and temperature to provide the total amount of
radiation required to maintain surface temperatures on earth suitable for life. Even small
changes in any of these factors would probably destroy all life.
c. The nearly circular orbit of the earth
limits temperature variations.
d. The water vapor and carbon dioxide in
the atmosphere produce a so-called "greenhouse effect" which moderates the
temperature extremes.
e. A high altitude ozone layer
effectively absorbs the lethal fraction of solar ultraviolet rays which would destroy life
on the earth's surface were the ozone layer removed.
f. The 23½.degree inclination of the
earth's axis of rotation from the perpendicular to the plane of its orbit provides for the
seasons. It probably also considerably increases the land area in the northern hemisphere
suitable for intensive summer agriculture.
g. The earth's magnetic field, extending
tens of thousands of miles into space, shields the earth's surface from much of the cosmic
radiation which probably would prove deleterious to life.
h. The lunar gravitation produces
important tidal circulation effects in the oceans, which make conditions much more
suitable for sea life, especially in the shallow zones along shores and in estuaries.
i. The mass and size of the earth are
adjusted to provide gravitational force and atmospheric pressure suitable for life, and
also to prevent the escape of the earth's atmosphere.
k. The earth's surface is blessed with a
concentration unknown any-where else in the universe, of liquid water, the only possible
solvent and medium for living cells. The physical properties of water are unique and
absolutely essential to all life processes. These properties of water include (1) the
highest heat of fusion(melting), (2) a liquid temperature range which includes the
temperatures at which enzymes and other life molecules can exist and function, (3) the
highest heat capacity(heat required to increase its temperature), (4) the highest heat of
vaporization, (5) the highest dielectric constant of all of the common liquids, (6) the
greatest solvent powers, (7) the greatest power to form a special chemical bond called a
hydrogen bond, (8) the greatest ionizing power of all the common liquids, (9) the property
(unique except for bismuth) of expanding when it crystallizes, and (10) a strong power to
absorb infrared radiation.
Liquid ammonia is sometimes proposed as a possible liquid for some imagined kind of
life system. It has slightly higher values in several of the above properties, but it is
distinctly inferior to water in the others. The idea of life in any solvent other than
water is mere fantasy.
l. The elements carbon, hydrogen, oxygen,
nitrogen, and phosphorus, together with liquid water, are the basis for the only remotely
possible chemical framework for life. The surface of the earth is the only known place in
the entire universe where these substances are found in suitable quantities and in the
proper forms for life to exist.
The ideal combination of conditions and factors essential to life observed only on
earth surely points to intelligent, purposeful design. To believe that this beautifully
balanced life support system which carries the human race safely at speeds of more than
one thousand miles per minute through hostile space is a mere accident requires invincible
faith in the power of chance. Would not any honest observer have to admit that the earth
appears to have been designed for us to live on, just as David the Psalmist said?