Forces and Fields

by Mary B. Hesse

Forces and Fields by Mary Hesse is a history of physics surrounding the "How do bodies act on one another across space?" Hesse illustrates this through various answers, discussing period of transition in fundamental physics in which new concepts and ideas have been introduced and made scientifically testable, and makes a certain philosophical interpretation of science from the beginning. Some topics include the logical status of theories, primitive analogies, mechanism in Greek science, the Greek inheritance, Corpuscular Philosophy, The Theory of Gravitation and The Theory of Relativity, as well as others. Mary B. Hesse (born 1924) was a contemporary English philosopher of science. She is now professor emerita of the philosophy of science at Cambridge University. Her publication Models and Analogies in Science is a widely cited and accessible introduction to the topic. Hesse argues, contra Duhem, that models and analogies are integral to understanding scientific practice in general and scientific advancement in particular, especially how the domain of a scientific theory is extended and how theories generate genuinely novel predictions. Examples of such models include the famous billiard ball model of the dynamical theory of gases and models of light based on analogies to sound and water waves. Hesse thinks that, in order help us understand a new system or phenomenon, we will often create an analogical model that compares this new system or phenomenon with a more familiar system or phenomenon. In her book, Hesse makes a distinction between three types of analogues in scientific positive analogies, negative analogies, and neutral analogies. Positive analogies are those features which are known or thought to be shared by both systems, negative analogies are those features which are known or thought to be present in one system but absent in the other, and neutral analogies are those features whose status as positive or negative analogies is uncertain at present. Neutral analogies are by far the most interesting of the three types of analogies, for they suggest ways to test the limits of our models, guiding the way for scientific advancement. In the late 19th century, for example, the idea that light-waves have a physical medium called the luminiferous ether would have been best thought of as a neutral analogy with water and sound waves. Eventually, due to a null result in the Michelson-Morley and Trouton-Noble experiments, as well as other similar experiments, this analogy came to be accepted as a negative analogy - we now accept that light has no physical medium, unlike sound and water waves. The discovery of this negative analogy led to further advancement, including the unification of electro-magnetic theory with optics, and the eventual creation of new and more informative models of light.

Genres: Physics, History, History Of Science, Science

332 pages, Paperback

First published January 1, 1961

Reviews

[J.D. Steens · Rating 3 out of 5]

As best as I can understand this largely inpenetrable book, Hesse explains the basis for action (movement) between objects in the non-organic world. Most interactions between objects are understood mechanically, between one object contacting another in a cause-effect relationship. Gravity challenges this mechanical explanation as there is evident movement between two objects without contact. Beginning with Faraday, the development of field theory provides an explanation for this "action at a distance" by stating that "'matter' is everywhere continuous and that "'atoms' are highly elastic and deformable, mutually penetrable, and," quoting Faraday, "'that matter fills all space, or, at least, all space to which gravitation extends.'" In this way, Hesse appears to be saying that atoms are seamed together, creating the fabric of space, and that it is this field that creates a linkage between two bodies.

While this explanation applies to substantive (such as they are) atoms, it is less clear if Hesse includes photons as part of the field as she writes that "photons can be called 'particles' only in the sense that they are bearers of this energy...but that they have none of the other usual mechanical properties of particles." This, in turn, prompts a question about whether a field in this sense is the same thing as dark energy and dark matter that is said to be space (fill space or space itself?).

Hesse exclusively focuses on inorganic matter, but there are questions about how the field concept might apply to life. She says that fields also operate at the micro level (electricity, magnetism; radiation) and, therefore, within our bodies. Are our bodies held together and moved not just by mechanical linkage (muscles, tendons) but also by fields of interconnected atoms? Is this how we pick up "vibes" from others?