The Division of the Waters (Part 3)
(This is excerpted from my The Everlasting Detective - a collection of unpublished essays)
At nearly the very beginning of Genesis, we read: "God said, `Let there be a vault in the waters to divide the waters in two.'" [Genesis 1:6] I will resist temptation: I will not speculate on what reality this corresponds to in nature. Certainly, for anyone who has seen the ocean, this description conveys an image of the sheer power and authority of God. Much more subtle is this placing of water in second place after light; it is now "organized" water - water which has been divinely divided, and not "primeval chaos" of the waters above which the Spirit hovered. And science pays homage to this primacy: most of the known matter of the universe is hydrogen, which is Greek for "that which gives birth to water." Even more subtle, water has been assigned a purpose - a purpose associated with God's power and authority to divide. Finally, this divided water is a symbol of the beginning of something.
There is another division of waters, and though on a much smaller scale, it also is the beginning of something, and powerful act of a divine purpose. This division is described in Exodus 14:19-22, though the arguments continue as to what body of water was affected. It was the culmination of that great event which "is to stand at the head of your calendar" - the Passover - the escape of the People of Israel from their slavery under the Egyptians. Awesome descriptions of this event appear in the Psalms, and echo in the many praises of God's power in the wonder of water:
The waters saw you, O God,
the waters saw you and trembled;
the depths were moved with terror.
The clouds poured down rain,
the skies sent forth their voice;
your arrows flashed to and fro.
Your thunder rolled round the sky,
your flashes lighted up the world.
The earth was moved and trembled
when your way led through the sea,
your path through the mighty waters,
and no one saw your footprints. [Psalm 77 from Morning Prayer of Wednesday Week II]
(Note: there are several other psalms which I quoted here originally: 93, 42, 147, 29, 74)
Perhaps there is nothing more amazing about God's division of the waters than the fact that water itself is a divider. Naturally, the idea of being divided by water suggests the ocean or a river. But even as a substance, water has a power of division. Water has many other properties, and the scientific knowledge about this ordinary marvel will indicate the cleverness with which it was planned.
H2O - the isosceles triangle
Chesterton's curious poet (or lunatic) named Gabriel Gale stared at a fishbowl and asked: "Were you ever an isosceles triangle?" [The Poet and the Lunatics,39] If he had taken about 18 grams (a little more than half an ounce) of water from that fishbowl, he would have about 600,000,000,000,000,000,000,000 very tiny isosceles triangles, each one an individual water molecule [The number 6.023e23, the number of things in a mole, is called Avogadro's number.].
One water molecule would fit into a box about 0.4 nanometers, or about 16 billionths of an inch, on a side. It is formed of three atoms: two hydrogens (H) and one oxygen (O). The three atoms are arranged in an isosceles triangle, with an angle of 104.5 degrees between the O-H bonds, which are 0.099 nanometers long (about 4 billionths of an inch). The bonds between the hydrogen and oxygen are "covalent" which means there is a sharing of electrons between the two atoms. But because of the stronger attraction of the oxygen, the electrons which are shared in the bonds of the water molecule tend to stay closer to the oxygen. This means that water is a dipole: it has a positive end (the two hydrogens) and a negative end (the oxygen), and is thus similar to a magnet.
This polarization is responsible for the various unusual properties of water. The positive ends of one water molecule attracts the negative end of another water molecule. Though this attraction between two separate molecules (which is known as hydrogen bonding) is not as strong as the attraction within one molecule, it is strong enough to have important effects. The most well-known of these is the fact that water expands when it freezes, and thus ice floats on water.
To explain this, it is well to remind ourselves that the water molecule exists in three dimensions. One should imagine a tetrahedron - a pyramid with a triangular base - with the oxygen in the center, the two positively charged hydrogens at two corners and two negatively charged electron pairs (in what are called sp3 hybrid orbitals) at the other two corners. One molecule of water thus has two positive corners and two negative corners, and can form the weaker hydrogen bonds with four other molecules of water. A mystic or a poet might here remark that the four arms of water (if viewed from the edge of the tetrahedron) would appear in the form of a cross, and its power of attraction might bring to mind the words of Christ: "And when I am lifted up [on the cross] from the earth, I shall draw all men to myself."[John 12:32]
As water is cooled, the molecules move slower and slower, and so they are more able to bond to each other. As they bond, they form regular crystalline shapes which occupy more space than when they are moving and not bonded. Thus, ice takes up more volume, more room than the same amount of liquid water, and so it is lighter and floats. These hydrogen bonds are also the reason why water requires so much heat before it will boil, since additional energy is required to break those bonds before the molecules are able to move freely.
The cruciform dipole of water and its ability to form hydrogen bonds gives it thermal properties which are unusual, or even, according to Harold McGee, "peculiar." The following comments on these properties are worth pondering:
The consequences of this peculiarity are considerable. It makes it possible for living organisms, which are from 50 to 95% water, to moderate the effect of sudden environmental temperature changes. Our bodies can absorb or lose substantial amounts of energy without becoming dangerously hot or cold.[On Food and Cooking 581]
Water's heat of vaporization, that is, the amount of heat required to convert water from a liquid to a gas at its boiling point (100 degrees C) is much larger than that of other liquids of comparable molecular weight. A large amount of heat is required to vaporize water even at its boiling point because on the average three hydrogen bonds must be broken before a water molecule escapes from the liquid into the gas phase.[Biochemistry 32-34]
Water requires a large exchange of heat to change its temperature and its state [state here means solid, liquid or gas]. Since water is a major component of all cells, its constancy of temperature minimizes temperature fluctuations within cells. This is of critical biological significance because important biochemical reactions occur only within a narrow temperature range. [Biochemistry 34]
Water has an abnormally high specific heat, the amount of energy required to raise its temperature by a given amount. That is, water will absorb quite a bit of energy before its temperature rises. For example, it takes 10 times the energy to heat an ounce of water 1 degree as it does to heat an ounce of iron 1 degree. In the time it
takes to get an iron pan too hot to handle on the stove, water will have gotten only tepid. One natural substance has a higher specific heat than water, and that is liquid ammonia.[On Food and Cooking 580-581]
(to be continued)