MIRACULOUS MOLECULE : WATER - 2
|
| |
A Temperate
World
The five different thermal properties of water
mentioned in Henderson's book The Fitness of
Environment also play a key role in bringing
about the mild and balanced climate that Earth
has.
Water's greater
latent heat and thermal capacity as compared with
other liquids are the reasons that bodies of water
heat up and cool off more slowly than does the
land. On land, the difference in temperature between
the hottest and coldest places can reach as high
as 140°C; at sea, that difference varies at most
between 15-20°C. The same situation exists in
the difference between daytime and nighttime temperatures:
in arid environments on land, the difference in
temperature can be as much as 20-30°C; at sea,
this is never more than a few degrees. And not
only the seas are affected in this way: the water
vapor in the atmosphere is also a big balancing
agent. One result of this is that in desert regions
where there is very little water vapor present,
the difference between daytime and nighttime temperatures
is extreme while in regions where a maritime climate
prevails, the difference is much less.
Thanks to these
unique thermal properties of water, the temperature
differences between summer and winter or between
night and day remain constantly within limits
such that human beings and other living things
can survive. If the surface of our world had less
water than it does land, the temperature differences
between night and day would have been much greater,
large tracts of land would have been desert, and
life might have been impossible or, at the very
least, much more difficult. Similarly, if the
thermal properties of water had been different
from what they are, the result would have been
a planet quite unsuitable for life.
Having examined
all these thermal properties of water, Henderson
concludes:
To
sum up, this property appears to possess a threefold
importance. First, it operates powerfully to
equalise and to moderate the temperature of
the earth; secondly, it makes possible very
effective regulation of the temperature of the
living organism; and thirdly it favours the
meteorological cycle. All of these effects are
true maxima, for no other substance can in this
respect compare with water. 1
 
The thermal properties
of water enable us to discharge excessive
heat from our body through sweating.
|
High Surface Tension
The properties
of water that we have considered till now are
thermal: that is, they are its heat-related properties.
Water also has a number of physical properties
which, as it turns out, are also extraordinarily
fit for life.
One of these
is water's surface tension, which is extremely
high. "Surface tension" is defined as a behavior
of the free surface of a liquid to act like an
elastic skin under tension. It is caused by attractive
forces between the molecules in the surface of
the liquid.
The best examples
of the effects of surface tension are to be seen
in water. Indeed, water's surface tension is so
high that some odd physical phenomena take place
as a result. A cup can hold a water mass which
is slightly higher than its own height without
spilling out. A metal needle carefully placed
on a motionless watery surface will float.
Plants are designed to take advantage
of water's high surface tension, thanks
to which, water can be made to rise many
meters up into even the highest leaves
of a forest canopy. |
The surface tension of water is much higher than
that of any other known liquid. Some of the biological
consequences of this are crucial and this is particularly
evident in the case of plants.
Have you ever
wondered how plants are able to convey water from
the depths of the soil many meters into the air
without pumps, muscles, or the like? The answer
to this puzzle is surface tension. The channels
in the roots and stems of plants are designed
to take advantage of water's high surface tension.
These channels grow thinner the higher they reach
and quite literally cause water to "creep up"
on its own.
What makes this
excellent design possible is the high surface
tension of water. If water's surface tension were
as low as it is in most other liquids, it would
be physiologically impossible for large plants
such as trees to live on dry land.
Another
important consequence of water's high surface
tension is the fragmentation of rock. Because
its surface tension is so high, water is able
to penetrate into the deepest recesses of rockthrough
the tiniest of cracks where it freezes when the
temperature drops below zero. Water, as we have
seen, is unusual in that it expands when it freezes.
This expansion exerts interior forces upon rock
that causes it eventually to break up. This process
is vitally important because it releases the minerals
trapped in rock into the environment and also
contributes to the formation of soil.
The Chemical
Properties of Water
In addition
to its physical properties, the chemical properties
of water are also extraordinarily fit for life.
Foremost among these properties is that it is
an excellent solvent: nearly all chemical substances
are capable of being dissolved in water.
A very important
consequence of this is that useful minerals and
similar substances that are locked up in the land
get dissolved in water and transported to the
sea by rivers. It is estimated that five billion
tons of such matter are carried into the sea every
year. These substances are vital for sea-life.
Water
also accelerates (catalyzes) nearly all known
chemical reactions. Another important chemical
property of water is that its chemical reactivity
is at an ideal level. Water is neither too reactive
and thus potentially destructive (as sulfuric
acid for example) nor is it too inert (like argon
which takes part in no chemical reactions). To
quote Michael Denton: "It seems that, like all
other properties, the reactivity of water is ideally
fit for both its biological and its geological
role."2
Additional details
concerning the fitness of the chemical properties
of water for life are constantly being revealed
as researchers investigate the matter more. Harold
Morowitz, a biophysics professor from the University
of Yale, makes this comment:
The
past few years have witnessed the developing
study of a newly understood property of water
(i.e., proton conductance) that appears to be
almost unique to that substance, is a key element
in biological-energy transfer, and was almost
certainly of importance to the origin of life.
The more we learn the more impressed some of
us become with nature's fitness in a very precise
sense… 3
Water's Ideal Viscosity
Whenever we think of a liquid,
the image that forms in our minds is that of
a substance that is extremely fluid. In actual
fact, different liquids have highly differing
degrees of viscosity: the viscosities of tar,
glycerin, olive oil, and sulfuric acid for example
vary considerably. And when we compare such
liquids with water, the difference becomes even
more pronounced. Water is 10 million times more
fluid than tar, 1,000 times more so than glycerin,
100 times more than olive oil, and 25 times
more than sulfuric acid.
As
this quick comparison should indicate, water
has a very low degree of viscosity. Indeed,
if we discount a few substances such as ether
and liquid hydrogen, water appears to have a
viscosity that is less than anything except
gases.
Does
water's low viscosity have any importance for
us? Would things be different if this vital liquid
were a little more or a little less viscous? Michael
Denton answers that question for us:
The
fitness of water would in all probability be
less if its viscosity were much lower. The structures
of living systems would be subject to far more
violent movements under shearing forces if the
viscosity were as low as liquid hydrogen...If
the viscosity of water was much lower, delicate
structures would be easily disrupted... and
water would be incapable of supporting any permanent
intricate microscopic structures. The delicate
molecular architecture of the cell would probably
not survive.
If the
viscosity was higher, the controlled movement
of large macromolecules and particularly structures
such as mitochondria and small organelles would
be impossible, as would processes like cell division.
All the vital activities of the cell would be
effectively frozen, and cellular life of any sort
remotely resembling that with which we are familiar
would be impossible. The development of higher
organisms, which is critically dependent on the
ability of cells to move and crawl around during
embryogenesis, would certainly be impossible if
the viscosity of water was even slightly greater
than it is. 4
| |
| Water's
low viscosity is vitally important to us.
If water were only slightly more viscous,
it would be impossible for blood to be transported
through the body's capillary system. For
example the complex system of veins of our
body's liver
would never have been able to exist. |
Water's low viscosity
is essential not only for cellular motion but also
for the circulatory system. All living creatures
with a body size of more than a quarter of a millimeter
have a centralized circulatory system. The reason
is that beyond that size, it is not possible for
nutriments and oxygen to be diffused throughout
the organism. That is, they can no longer be taken
directly into the cell nor can their by-products
be discharged. There are many cells in an organism's
body and thus it is necessary for the oxygen and
energy taken into the body to be distributed (pumped)
to them through "ducts" of some sort; similarly,
other channels are necessary to carry away the waste.
These "ducts" are the veins and arteries of the
circulatory system. The heart is the pump that keeps
this system moving while the substance carried through
the "ducts" is the liquid we call "blood", which
is mostly water. (95% of blood plasma–the material
remaining after blood cells, proteins, and hormones
have been removed, is water.)
This
is why the viscosity of water is so important
for the efficient functioning of the circulatory
system. If water had the viscosity of tar for
example, certainly no organic heart could pump
it. If water had the viscosity even of olive oil,
which is a hundred million times less viscous
than tar, the heart might be able to pump it,
but it would be extremely difficult and blood
would never be able to reach all the billions
of capillaries that wend their ways through our
bodies.
Let's
take a closer look at those capillaries. Their
purpose is to carry the oxygen, nourishment, hormones,
etc that are necessary for life to every cell
everywhere in the body. If a cell is more than
50 microns (a micron is a thousandth of a millimeter)
away from a capillary it cannot take advantage
of the capillary's "services". Cells more than
50 microns from a capillary will starve to death.
This
is why the human body was so created that the
capillaries form a network that pervades it completely.
A normal human body has about 5 billion capillaries
whose total length, if stretched out, is about
950 kilometers. In some mammals, there are as
many as 3,000 capillaries in a single square centimeter
of muscle tissue. If you were to gather ten thousand
of the tiniest capillaries in the human body together,
the resulting bundle might be as thick as the
lead of a pencil. The diameters of these capillaries
varies between 3-5 microns: that's three to five
thousandths of a millimeter.
If
blood is going to penetrate passages that narrow
without blocking them or slowing down, it certainly
needs to be fluid and, thanks to water's low viscosity,
it is. According to Michael Denton, if water's
viscosity were just a bit more than what it is,
the blood circulatory system would be completely
useless:
A
capillary system will work only if the fluid
being pumped through its constituent tubes has
a very low viscosity. A low viscosity is essential
because flow is inversely proportional to the
viscosity... From this it is easy to see that
if the viscosity of water had a value only a
few times greater than it is, pumping blood
through a capillary bed would require enormous
pressure and almost any sort of circulatory
system would be unworkable... If the viscosity
of water had been slightly greater and the smallest
functional capillaries had been 10 microns in
diameter instead of 3, then the capillaries
would have to occupy virtually all of the muscle
tissue to provide an effective supply of oxygen
and glucose. Obviously the design of macroscopic
life forms would be impossible or enormously
constrained... It seems, then, the viscosity
of water must be very close to what it is if
water is to be a fit medium for life.5
In
other words, like all its other properties, the
viscosity of water is also "tailor-made" for life.
Looking at the viscosities of different liquids,
we see that they differ by factors of many billions.
Among all those billions there is one liquid whose
viscosity has been created to be exactly what
it needs to be: water.
Conclusion
Everything
that we have seen in this chapter since its beginning
shows us that the thermal, physical, chemical,
and viscosity properties of water are exactly
what they must be in order for life to exist.
Water is so perfectly designed for life that,
in some cases, the very laws of nature are suspended
to make it so. The best example of this is the
unexpected and inexplicable expansion that takes
place in water's volume when its temperature falls
below 4°C: if that didn't happen ice wouldn't
float, the seas would freeze all but solid, and
life would be impossible.
Water
is "just right" for life to a degree that cannot
be compared with any other liquid. The larger
part of this planet, a world whose other attributes
(temperature, light, electromagnetic spectrum,
atmosphere, surface, etc) are all suitable for
life, has been filled with just the right amount
of water necessary for life. It should be obvious
that this cannot all be accidental and that there
must instead be intentional design.
To
put it another way, all the physical and chemical
properties of water show us that it is created
especially for life. The earth, purposefully created
for mankind to live in, was brought to life with
this water that was specially created to form
the basis of human life. In water, Allah has given
us life and with it He causes the food by which
we are nourished to spring from the soil.
But
the most important aspect of all this is that
this truth, which has been discovered by modern
science, was revealed in the Qur'an, bestowed
upon humanity as a guide fourteen centuries ago.
Concerning water and mankind, Allah's word is
revealed in the Qur'an thus:
It is
He who sends down water from the sky. From it
you drink and from it come the shrubs among which
you graze your herds. And by it He makes crops
grow for you and olives and dates and grapes and
fruit of every kind. There is certainly a Sign
in that for people who reflect. (Surat an-Nahl:
10-11)
|
