Release notes: The many faces of energy

Energy is everywhere. It powers our homes and businesses, our trains and automobiles; a whole industry has built up around it. We count it in calories, yet we often wish we had more of it. We admire it in art, literature, and film. We feel it in a football stadium, at a rock concert, and in a romantic encounter. Alternative medicine taps into it, and science fiction wields it as a weapon. But what is energy? Over the past eighteen months, our energetic lexicographers have devoted some of their energies to revising the noun energy and related entries from energate to energizing. We have also added dozens of new energy-related senses, subentries (from energy bill to zero-point energy), and entries (from energeticism to energy vampire to positive energy). Now is an opportune moment to offer a short overview of the history and development of this pervasive word, energy.

Power, strength, efficacy

In a way, energy has only one core meaning: ‘power, strength, force; the ability or capacity to produce an effect’. This general concept underlies various more specific senses of energy and its immediate etymons, Latin energia and Greek ἐνέργεια. In fact, by the time energy entered English in the mid-sixteenth century, the Latin and Greek terms already had long-established applications in a number of different contexts, such as rhetoric and philosophy, and as a result, corresponding senses of energy soon emerged in English. Many of these early senses of energy are now rare or obsolete. In rhetoric, energy is the capacity of words or language to effectively express an idea. According to Aristotelian metaphysics, energy (ἐνέργεια) is the actual working of something, as opposed to its potential or capacity to do work (δύναμις).

In the eighteenth century, new specific applications of energy‘s core meaning began to emerge. Philosopher and sometime grammarian James Harris—called ‘Hermes Harris’ after his book Hermes: or, A Philosophical Inquiry Concerning Language and Universal Grammar (1751)—co-opted energy as a grammatical term, calling the action of a verb its energy; he also called a verb which expresses action an energy. These terms ceased to be used by the end of the nineteenth century; grammarians now use the terms action and action verb, respectively. Perhaps harking back to the Aristotelian sense mentioned above, the plural form energies came to refer first to a person’s collective actions, and later to a person’s collective physical and mental powers. This sense is still current today, in phrases such as to devote one’s energies to something.

It was also towards the end of the eighteenth century that energy developed one of the senses most familiar to us today: that of ‘vigour, intensity, or dynamism’. This sense was first applied as a quality of movement, activity, art, and so forth (e.g. ‘the piece of music concluded with energy’), and subsequently as a personal quality (e.g. ‘the poet admires a person of energy’). There will be more to say about this sense below.

The science of energy

In January 1802 one man changed energy forever. A young English physician named Thomas Young had recently been appointed Professor of Natural Philosophy at the Royal Institution in London. Young’s main task was to prepare and deliver a series of fifty lectures on natural philosophy, the first seventeen of which dealt with mechanics, the branch of physics that deals with objects in motion and the action of forces. A detailed syllabus of Young’s lectures was issued on 19 January 1802, the day before the first lecture. In the syllabus for the eighth lecture, ‘On collision’, Young termed ‘the product of the mass of a body into the square of its velocity’ (previously called vis viva) its energy because this quantity represents the capacity of a moving body to perform mechanical work. For instance, the depth to which a bullet can penetrate a substance is proportional to this quantity, as is the height which a vertically ascending projectile will attain before it begins to fall. What Young termed energy is now called more specifically kinetic energy (½mv2), and energy has been generalized to include not only kinetic energy, but also the capacity of a body or system to do work by virtue of its position, chemical structure, etc., called potential energy. A plethora of terms such as radiant energy, rest energy, and dark energy, in which the first element indicates the nature, form, or source of energy, have already been revised or added to the OED.

Energy became such an important scientific concept that there developed an entire field, energetics (recorded earliest in 1855), concerned with the use, transfer, loss, etc., of energy in physical, chemical, and biological systems and processes. Towards the end of the nineteenth century, a doctrine or theory of energeticism (also called energism or energetics) emerged. Energeticists argued that changes in energy form the basis of all physical phenomena, and that energy (rather than atoms) is the fundamental constituent of the universe. Einstein’s realization that there is a physical relationship between energy and mass, given by the equation E = mc², helped render moot the debate between energeticists and atomists. Energy‘s primordial nature still captures the imagination in science fiction, where pure energy can be formed into a projectile or beam and fired from an energy gun (1917), typically with destructive effect. This sense, new to OED in this update, has been traced as far back as 1903.

Machines and devices require energy, in the form of fuel or electricity, in order to operate: this energy, derived from the exploitation of physical and chemical resources, is frequently regarded as a resource or commodity. The importance of the energy industry in the modern world is reflected in an explosion of energy compounds relating to the production and supply of electricity and gas and other fuels, or to government control and regulation of this; many of which date from the early decades of the twentieth century. Terms revised and drafted in this update include energy company (1910), energy bill (1911), energy market (1920), energy audit (1936), energy crisis (1953), and energy crunch (1970). These are in addition to numerous terms already revised or added to OED3, such as renewable energy (1909), nuclear energy (1927), alternative energy (1975), and green energy (1980).

A quantifiable resource: energy for a New Age

The scientific and industrial senses of energy had a lasting impact on other senses of the word. Perhaps the most profound change was that energy acquired a new semantic dimension: quantity. Prior to the nineteenth century energy was normally used as an unmeasured quality or attribute; a person or thing either possessed energy or did not. Once Young defined energy as mv² it became quantifiable. An object of greater mass, or moving at a greater speed, possesses more energy than a lighter or slower object. This idea began to be readily applied to other senses of energy. For example, in the familiar sense ‘vigour, intensity, or dynamism’, discussed above, energy is commonly regarded as a quantifiable attribute or resource. A piece of music can end with ‘a great deal of energy’; one person can have ‘more energy’ than another.

As a personal quality or resource, energy has become conceptually linked to the physical energy required by the biochemical system we call the human body. If a person has low energy, it might be attributed to a slow metabolism, while children can ‘burn off’ excess energy running and playing in the schoolyard. Supermarket shelves are stocked with endless varieties of energy drink (1904) to help you excel in sports or overcome tiredness, and an energy bar (1917) might be just what you need to ‘fuel’ your next workout.

The sense of energy used in the context of certain Eastern religions and New Age philosophy to mean ‘a spiritual or ethereal force held to be present in all living things’ has been added to the OED in this update, and is attested as far back as 1816. Like the energy industry, this sense has engendered a raft of energy compounds dating back to the first half of the twentieth century, such as energy channel and energy centre, as well as more recent compounds relating to alternative medicine, such as energy healing (1978).

Energy as vigour or intensity seems to meld with the scientific and New Age senses in the newest sense of energy to enter the OED in this update, that of ‘a perceptible quality, state, or feeling present in a place or within a group at a given time, esp. one of excitement, antagonism, tension, suspense, etc.’ (1957). Despite its relatively recent emergence, this sense has become very familiar, from the energy in the room to the energy at a rock concert, from the negative energy of a defeated team to the positive energy of the victors. We have all experienced this kind of energy at one time or another; and like the very earliest senses of energy, it has power, strength, and the capacity to produce an effect in us.

The opinions and other information contained in the OED blog posts and comments do not necessarily reflect the opinions or positions of Oxford University Press.