One of the four Aristotelian elements, water has played a central role in scientific thought for millennia. 1 To the physical scientist it is a continuing source of fascination because of its many unusual and counterintuitive properties. For example, liquid water, if sufficiently cold, expands and becomes more compressible when cooled, and less viscous when compressed. Water can also exist in at least two distinct glass forms–a phenomenon known as polyamorphism.
Water is not only fascinating, but it is also one of the most important and ubiquitous substances on Earth. There are 1.3 × 109 km3 of water in the oceans, 3.3 × 107 km3 in the polar ice caps, 2 × 105 km3 in glaciers, 105 km3 in lakes, and 1.2 × 103 km3 in rivers. In addition, 2.2 × 105 km3 of water fall annually as...
