Dear Colleagues,

Shannon’s (1948) work “A Mathematical Theory of Communication”, has generated a great deal of confusion between the general concept of “Information” and so-called “Information Theory.” The latter deals with a specific kind of information, not with any information. This is one source of confusion.

The second confusion arose between Shannon’s measure of information (SMI) and entropy. As Shannon emphasized in his publication the measure of information he defined is not a measure of any information, but rather a measure of information belonging to, or contained within a probability distribution. Entropy, on the other hand, has a similar mathematical form as SMI. Therefore, Entropy can be said to be a special case of SMI. However, the SMI as defined by Shannon is, in general, not Entropy.

Unfortunately, the literature is replete with confusing the two concepts, entropy and SMI. Fanning the confusion are some authors who muddle between entropy and SMI and identify the theory of information with the theory of thermodynamics.

It is our hope that this issue will help to dissolve the issue of entropy and the confusion that goes with it that is quite common in recently published articles and books. It is quite easy to understand why this confusion has seeped and diffused into the two most difficult concepts in science: life and the universe. Both of these are fascinating fields of research, yet far from being understood. It is not surprising that authors of popular science books have capitalized on this fact to use the concepts of SMI and entropy to life phenomena and for the entire universe. SMI and entropy are well-defined concepts. They have been applied successfully to specific and well-defined aspects of life and of the universe. For example, specific chemical reactions in biology, heat engines, and phase transitions in thermodynamics. The question is whether these two concepts can or cannot be applied to either an entire living system or to the entire universe. The main question that we wish to raise in this issue is whether these two concepts can, or cannot, be applied to either an entire living system or to the entire universe. We invite papers that discuss this question. 

Prof. Dr. Arieh Ben-Naim
Guest Editor

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• information
• Shannon’s measure of information
• entropy
• thermodynamics
• the second law
• life and the universe