In last week’s post, we finished up by learning of Sadi Carnot’s eventual recognition that the phenomenon of heat relates to the smallest-scale motions of matter. I’ll start the last stage in our historical overview by introducing the term energy itself for the first time.Note 1 Up until early in the nineteenth century, the name ‘living force’ prevailed in relation to the quantity mv2, the product of a body’s mass and the square of its speed. Then in 1807, in A Course of Lectures in Natural Philosophy and the Mechanical Arts, Thomas Young (1773-1829) proposed the term ‘energy’ as an alternative to ‘living force’.Note 2 It’s noteworthy that in doing so, Young was not interested in whether this energy had some sort of metaphysical significance i.e. whether it had some sort of inherent existence. Rather, he was interested in the observation that in many physical situations, characteristic effects are proportional to this quantity, that it arises as an invariant feature of certain physical situations. Continue reading
In last week’s post I commenced a brief and highly selective look at the history of the energy concept. The purpose of this historical approach to our inquiry is to get some sense of how the pioneering investigators might have made sense of their experience of the physical world, unaided—and hence also, in a sense, unconstrained—by the conceptual tools that we take for granted today. This in turn might help us to get a better sense of what the energy concept is all about in experiential terms. The aim of all of this is to ensure that, in thinking about societal energy challenges and dilemmas, we hold the conceptual tools, rather than the conceptual tools holding us.
We started out in Part 1 by considering some of the early forerunners of the modern energy concept through the work of Galileo, Descartes and Leibniz, all important pioneers in the branch of physics known as mechanics. While the contributions of these investigators all preceded the arrival of the earliest heat engines—the general class of machines that enabled the rise of industrial society, and that continue to provide the overwhelming majority of electricity and transport today on a global scale—they had little direct influence on the rise of the mechanised world. For most practical intents and purposes, we can consider the historical precedents of the modern energy concept in terms of two largely independent paths: the physicists and mathematicians travelled by one route; on the other, we find the engineers. These paths would eventually undergo a significant convergence, but at the end of the seventeenth century, the two groups typically had quite distinct interests. While we might say that the physicists tended to focus on describing and explaining physical phenomena, the engineers were interested in harnessing physical phenomena for practical human purposes. Nonetheless, there were still important instances of crossover between the groups. The French physicist and mathematician Guillaume Amontons (1663-1705) was an important figure in this respect. Not only did he propose a conceptual design for a novel heat engine, in work published in 1699 he attempted to quantify its useful effect in terms of the labour of “men and horses”, still at that time the dominant prime movers for most areas of economic activity. In doing so, he effectively pre-empted the concept of work. Motivated by the engineers’ need for a means of quantitatively comparing performance amongst different types of machines, the work concept as we know it today emerged during the early years of the eighteenth century. Continue reading
This week’s post is the first in a three-part introduction to the formal language of energy, as a foundation for subsequent discussion about just what it is that the energy concept deals with. My aim is to cover some essential ideas here—where they come from, how they relate to one another—in sufficient detail for later inquiry into the higher-level relationships between energy and societal futures. A central purpose of the approach I’m advocating is to maintain a connection between our understanding and use of energy-related concepts, and day-to-day experience of our physical world. It’s my contention that we might then be better placed to appreciate and respond to the societal dilemmas we’re confronted with through clear eyes—as free as possible from the fog of confused conceptions. To this end, I’ll commence from the outset by situating energy, as is proper to the nature of that concept, in a systems context—and this requires a basic introduction to systems ideas in their own right. Further along the track, we’ll then be able to build on these ideas—systems in general, and energy from a systems perspective—as appropriate to the inquiry at hand. The overall ‘narrative of ideas’ running through the three posts introduces three foundational ‘laws’ relating to the behaviour of physical systems in energetic terms. A very simple situation will be used to illustrate each of the three laws, providing an opportunity to appreciate what each means in terms of familiar experiences. Part 1introduces the systems view as an approach to thinking about any situation in which we’re interested, and with this as background, looks into energy law 1, that of energy conservation. In Part 2, I’ll look at energy law 2, relating to energy dispersal; and in Part 3 I’ll take an in-depth look at energy law 3, sometimes paraphrased as the ‘economy law’.
In last week’s post, I introduced the energy concept as the capacity to do work or transfer heat. In establishing this relationship between energy, work and heat, we have a handy basis for linking energy—an abstract concept used to think and communicate about physical situations in which we’re interested—with direct physical-world experiences. For while work and heat have very precise meanings in this context—they are formally defined, abstract concepts in their own right—these meanings relate closely to the common use of these terms in everyday language. Before we delve further into energy, work and heat though, there’s a more basic matter that we need to deal with, one that goes right to the heart of developing an effective working relationship with the energy idea: a capacity is always a capacity of something. But just what is it exactly that has this capacity that we’re interested in?