I should teach the world that energy cannot be created or destroyed; it can only be converted from one form to another. This is the simple and elegant statement of the law of conservation of energy - a concept that has profound implications for any discipline that purports to be a science.

This concept is fundamental to the theory of thermodynamics, and is encapsulated in the first of the three laws of thermodynamics - a cornerstone of physics that has enabled us, among other things, to build efficient machines, to analyse the workings of the human body, to synthesise chemicals, and to understand the processes that power our Sun. The concept is also inextricably linked to Albert Einstein's much-quoted special relativity relation, E = mc².

E = mc² is probably the most recognisable equation in science, with countless posters, T-shirts, and coffee mug appearances over the past 100 years. It is also probably the least understood equation in science. In it, the principle of the conservation of energy is given simple mathematical expression, where matter is shown to be a form of energy related by the speed of light, c.

Einstein said of thermodynamics: 'A theory is more impressive the greater the simplicity of its premises, the more different are the kinds of things it relates, and the more extended its range of applicability, therefore, the deep impression which classical thermodynamics made on me. It is the only physical theory of universal content which I am convinced, that within the framework of applicability of it basic concepts will never be overthrown.'

A basic understanding of the conservation of energy and thermodynamics beautifully illustrates the impact that science can have upon the way we live our lives. But the fundamental nature of the subject, and its simplicity, also allow a look at current scientific theories - which can often seem inaccessible, complicated, and therefore unnecessary. In a time when the word 'science' is increasingly used to legitimise concepts and ideas that are far from scientific, a reminder of what real science is and does would benefit everyone.