History of Energy - Thermodynamics

Thermodynamics

The development of steam engines required engineers to develop concepts and formulas that would allow them to describe the mechanical and thermal efficiencies of their systems. Engineers such as Sadi Carnot, physicists such as James Prescott Joule, mathematicians such as Émile Clapeyron and Hermann von Helmholtz, and amateurs such as Julius Robert von Mayer all contributed to the notion that the ability to perform certain tasks, called work, was somehow related to the amount of energy in the system. In the 1850s, Glasgow professor of natural philosophy William Thomson and his ally in the engineering science William Rankine began to replace the older language of mechanics with terms such as "actual energy", "kinetic energy", and "potential energy". William Thomson (Lord Kelvin) amalgamated all of these laws into the laws of thermodynamics, which aided in the rapid development of explanations of chemical processes using the concept of energy by Rudolf Clausius, Josiah Willard Gibbs and Walther Nernst. It also led to a mathematical formulation of the concept of entropy by Clausius, and to the introduction of laws of radiant energy by Jožef Stefan. Rankine, coined the term "potential energy". In 1881, William Thomson stated before an audience that:

The very name energy, though first used in its present sense by Dr Thomas Young about the beginning of this century, has only come into use practically after the doctrine which defines it had ... been raised from mere formula of mathematical dynamics to the position it now holds of a principle pervading all nature and guiding the investigator in the field of science.

Over the following thirty years or so this newly developing science went by various names, such as the dynamical theory of heat or energetics, but after the 1920s generally came to be known as thermodynamics, the science of energy transformations.

Stemming from the 1850s development of the first two laws of thermodynamics, the science of energy have since branched off into a number of various fields, such as biological thermodynamics and thermoeconomics, to name a couple; as well as related terms such as entropy, a measure of the loss of useful energy, or power, an energy flow per unit time, etc. In the past two centuries, the use of the word energy in various "non-scientific" vocations, e.g. social studies, spirituality and psychology has proliferated the popular literature.