In the Beginning was Information

A3 EnergyA3.1 Energy, a Fundamental QuantityThe concept of energy (Greek energeia = activity) plays such a central rolein all of physics as well as in the other natural sciences and in technology,that it is regarded as a fundamental entity, as information is shown to be.But, in contrast to information, energy belongs to the material world – thelowest level of Figure 14 (Chapter 4). Energy appears in numerous forms,many of which can be converted into another form. Very many physicalprocesses fundamentally involve nothing else than the conversion of oneform of energy into another. The most important forms of energy are:– mechanical work (energy),– potential and kinetic energy (energy of rotation and energy of translation),– the energy of gravitational fields, and of electrical, magnetic, and electromagneticfields,– heat energy,– electrical energy,– the energy which binds nucleons in atomic nuclei,– chemical energy,– radiation energy of particles (electrons, protons, and neutrons), and– the equivalence of mass and energy.All physical events and processes obey two fundamental principles,known in thermodynamics as the “first law” and the “second law”.The first law: This important natural law, also known as the “energy law”or the “law of conservation of energy”, was first formulated in 1842 by aGerman physician, Robert Mayer (1814 – 1879). It states that energy cannotbe created in the observable world, neither can it be destroyed. This law isnot an axiom, but is derived from experience as are all natural laws (see theoremN1, paragraph 2.3). In every chemical or physical process the totalenergy of the system and its environment, and thus also the total quantity ofenergy in the universe, remains constant. It is thus impossible to destroyenergy or to add to the total quantity of energy. It can only be converted intoother forms. Some important consequences of the energy law are:– Only events which do not change the total amount of energy, can occurin nature. Walter Gerlach (1889 – 1979), a German physicist, formulatedthis principle as follows [R1]: “The law of the conservation ofenergy plays the role of a police commissioner: it decides beforehandwhether a line of thought is acceptable or forbidden.”223