25 



Information Theory 

 and Biology 



I. Languages 



It is often said that mathematics is the language of physics. Perhaps, 

 more strictly speaking, one should assign this role to calculus. Isaac 

 Newton was a leader in the development of this branch of mathematics ; 

 calculus enabled Newton and those who followed him to more con- 

 veniently describe the physical world. Ever since Newton's time, 

 calculus and its ramifications have developed side by side with physics. 

 Some purely mathematical theorems have been later applied in physics; 

 and some physicists have developed mathematical tools which could 

 not be justified or made rigorous for years to follow. 



In this chapter, information theory is presented as a branch of applied 

 mathematics which has become a convenient language in many varied 

 fields. It is included in this section of the text because information 

 theory is so closely related to the ideas of thermodynamics, particularly 

 the concept of entropy. In biophysics, research workers describe 

 experiments in terms of information theory when discussing sensory 

 biophysics, molecular biology, genetics, and the operation of special 



460 



