THE SYSTEMS CONCEPT 



detectors 



"SYS TEM" 

 Figure 1-1. The Parts of a System. 



the reader should always have this organization in the back of his mind dur- 

 ing study of the following pages. 



Some of systems engineering can be reduced to mathematical description. 

 Many details of medical physics can be reduced to simple arithmetical or 

 algebraic expression. Hence, in this subject of biophysics, mathematical 

 terminology is very useful, and in fact in some special cases quite necessary, 

 if the length of the description of the subject matter is to be kept within 

 reasonable limits. 



INTRODUCTION TO THE TEN PILLARS 



Mathematics has been defined as the concise, quantitative expression and 

 development of ideas. It is in this sense that we shall use the material to 

 follow. 



Concise, quantitative description of natural phenomena is the goal of the 

 physical scientists. Indeed, Lord Kelvin (1883) has written." "I often say 

 that 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 meager and 

 unsatisfactory kind; it may be the beginning of knowledge, but you have 

 scarcely in your thoughts advanced to the stage of science." The approach 

 made in this book introducing biophysics is to use the mathematical method 

 of concise expression wherever possible without allowing the elegance to 

 cloud the facts or ideas being discussed. Cumbersome manipulations have 

 been omitted, and the methods have been used only when they serve in a 

 simple manner to display clearly the material being discussed. 



