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Water is the essence of life on this planet and perhaps throughout the universe. It has been credited with mystical powers through the ages, and today, science has found that water does indeed have strange powers. Life's Matrix chronicles the history of water from the first hydrogen and oxygen atoms, to water's subsequent distribution on planets, moons, and meteors. It also tells of our changing understanding of water, from its being one of the four elements of Aristotle -- along with earth, air, and fire -- to the discovery of its true structure.
This familiar molecule, which moves so easily from solid to liquid to gas on our planet, is unlike any other. Philip Ball has a knack for explaining the behavior of atoms and molecules. This line of research is officially called "materials science," which may sound staid at first, but it is the science that explains why things are the way they are, and how to create new things that have weird and wonderful properties. In this case, water already possesses some of the weirdest. For example, most substances are heavier in their solid state than in their liquid state for the very simple reason that the molecules are packed more tightly together in a solid. Likewise, molecules are even farther apart in a gaseous state, a nice progression. How then, can ice float on liquid water? This question stumped scientists who preferred to study other liquids that behaved in a more logical manner. Ball gives a vivid explanation of this anomaly. The water molecule is bent. To be more exact, the hydrogen atoms are splayed at an angle of 104.5 degrees. This leaves two lone pairs of electrons in the other corners of what should be water's most stable shape, a tetrahedron (a solid that has triangular sides).
Imagine that you are the water molecule. Stand with your arms raised in a V and your legs spread apart. Your hands are the hydrogen atoms, and your feet are the electron pair. You are tumbling around grabbing the ankles of other molecules while they grab yours, everyone grabbing and letting go as they pass by, bumping into one another. That's liquid water. Now everyone stops and keeps ahold of the ankles. There's more space now in between than when everyone was bumping into each other. That's ice. There's actually a way of making super-dense ice where the interlocked rings cross into the empty spaces, but for life on earth, floating ice has meant that oceans have remained liquid underneath, sheltered and protected instead of being frozen solid. This is just one example of water's properties. Ball describes how water works in living organisms and why it is so good at dissolving, which is essential to the planet's task of recycling needed elements.
Ball ends with an epilogue on water as a scarce resource. It's so ironic that water may supplant oil as the irreplaceable resource humankind would fight for the world over, something, though, that desert-dwelling people have understood for millennia.
--Laura Wood, Science & Nature Editor