This paper will cover the evolution of the idea of ‘Entropy’ from the idea of temperature(1) and engines to the Second Law of Thermodynamics which has churned out scientific paradigms and raised philosophical questions; then the origin of the ‘entropy’ as a classical thermodynamics property by Rudolph Clausius in 1865(2), its statistical thermodynamical interpretation by Ludwig Boltzmann in 1877(3), and the using of ‘entropy’ in the Information Theory in 1948 by Claude Shannon(4), opening up its application and interpretation in newer fields – which seems to be an ongoing process.
Application of the ‘entropy’ concept has been in all branches of Engineering (particularly Mechanical, Chemical and Metallurgical), Physics (from Classical to Molecular)(5), Physical Chemistry(6), recently in Information Theory, very recently in Quantum Computing, Reverse Computing. Also, there is the process of entropy generation and its minimization ideas and their application in the Design of Nature by Bejan(7). A Mosaic of Ideas, entropy concept has remained enigma in the field of History of Science.
The paper will trace the application of the phenomena of rise in temperature and the engine concept in the Hellenistic period (Galen & Hero) to Renaissance Europe (Galileo) to the evolution of Steam Engine, the 2nd Law of Thermodynamics, Chemistry and Information Theory.
In India, around 1100 AD, the perpetual motion machine is mentioned but not ‘entropy’, though ‘transformation’ (the Greek word’s meaning) has been a widely discussed topic in Philosophy and Chemistry in India(8).
This review will be useful not only to understand ‘entropy’ but also to show the universal spread of the nature of Science and Technology. This seems to be a path along which we travel, more than a ‘point property’.
Keywords: Second Law, entropy, entropy generation, disorder of molecules, information theory, thermal equilibrium.