PRE-ORGANIC EVOLUTION 



cations been expanded to a point where it bears very 

 little apparent relationship to its original definition in 

 terms of available energy. The manner in which the 

 term entropy is used, for example, in cybernetics has 

 transformed it fully into a concept that measures the 

 probability of a system, rather than the energy levels. 

 It is indeed difficult to understand the relation to avail- 

 able energy if one considers such a statement as "the 

 entropy of a message" or "of a book" or "of a clock 

 mechanism." Because of this situation, the author in- 

 tends for use in this book, to re-define the term entropy 

 to distinguish between the meaning that entropy has 

 in classical thermodynamics and the concept of en- 

 tropy used as a measure of randomness. To do so may 

 appear unnecessary to some readers. The separation 

 however, cannot do any harm, but will prevent confu- 

 sion. From now on therefore, the term entropy as used 

 in this text shall refer exclusively to the concept of 

 randomness of a system. 



As most of the material in this book will be con- 

 cerned with orderly systems, a term expressing order- 

 liness is more convenient to use than one dealing with 

 randomness. Such a term can be found, by giving a 

 name to the reciprocal of "entropy". We shall name 

 this reciprocal "extropy."* 



If one follows the evolutionary development of our 



^The use of the terra extropy has been suggested to the author by Pro- 

 fessor Paul Kosok of Long Island University. The meaning of this term 

 is quite similar to the "negentropy" referred to by Erwin Schroedinger 

 in his book What is Life? 



17 



