11. Conservation of Mass,       Charge, and Energy   Previous PageNext Page
       Introduction: You Can't Get Something for Nothing...

The first ten chapters of this book have been mainly descriptive. They have portrayed the material universe as seen by an observer who has the ability to adjust his field of view to encompass entire galaxies or single atoms. At the lowest level we have seen how electrons can be arranged around nuclei in atoms, and how this arrangement limits the different kinds of atoms that can exist. At a slightly higher level of organization we have seen the way in which electrons hold groups of atoms together in molecules of definite size and shape, and how the properties of matter depend on molecular structure. This is the essence of chemistry: to explain matter in molecular terms.

Like any other branch of science, chemistry eventually becomes trivial if it remains descriptive. The essence of science is control of matter by means of successful predictions of behavior; and predictions without measurement are hazy. Sooner or later we must adopt the viewpoint of William Thomson (Lord Kelvin), a pioneer in thermodynamics and electricity, who said in 1891:

"When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. It may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science."

William Thomson (later Lord Kelvin) 1824 - 1907
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