Search: Submit Search Home Encyclopedia Summa Fathers Bible Library A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Home > Catholic Encyclopedia > E > The Law of Conservation of Energy The Law of Conservation of Energy Please help support the mission of New Advent and get the full contents of this website as an instant download. Includes the Catholic Encyclopedia, Church Fathers, Summa, Bible and more — all for only $19.99... Amongst the gravest objections raised by the progress of modern science against Theism, the possibility of miracles, free-will, the immateriality of the human soul, its creation and immortality, are, according to many thoughtful men, those based on the Law of the Conservation of Energy. Consequently, as full a treatment of this topic in its philosophical aspects as the limits of space will allow, is here attempted. Explanation of the doctrine The word energy comes from the Greek ’enérgeia, "operation", "actuality". This term is itself a compound of ’en and ’érgon, "work". In modern physical science the notion of energy is associated with mechanical work. It is commonly defined as "the capacity of an agent for doing work". By "work" scientists understand the production of motion against resistance. Such energy, whilst existing in many forms, is considered especially in two generically distinct states known as kinetic energy, or energy of motion, and potential energy, or energy of position. The power of doing work in the former case is due to the actual motion possessed by the body, e.g. a cannon-ball on its course, or a swinging pendulum. Potential energy, on the other hand, is exemplified by a wound-up spring, or by the bob of a pendulum when at its highest point; as the bob swings upwards its velocity and kinetic energy continuously diminish, whilst its potential energy is increasing. When at its highest point its potential energy is at a maximum, and its kinetic is nil. Conversely, when, moving downwards, it reaches its lowest point, it will have recovered its maximum kinetic energy, whilst its potential will have vanished. Energy is also recognized in the heat of a furnace, or the fuel of the same, in explosives, in an electric current, in the radiations of the ether which illuminates and warms the earth. Now, it has been found that these different forms of energy can be changed into one another. Further, the amount of a sum of energy in different forms can be measured by the quantity of work it can accomplish. A weight suspended over a pulley can be employed to do work as it sinks to a lower level; likewise a steel spring as it expands, heat as it passes to a cooler body, electric current as it is expended, and chemical compounds in the course of decomposition. On the other hand, a corresponding amount of work will be required in order to restore the original condition of the agents. Perhaps the greatest and most fruitful achievement of modern physical science during the past century has been the establishment of a law of quantitative equivalence between these diverse forms of energy measured in terms of work. Thus a certain amount of heat will produce a definite amount of motion in a body, and conversely this quantity of motion may be made to reproduce the original amount of heat—assuming that in the actual process of transformation there were no waste. In other words, it is now accepted as established that, in any "conservative" or completely isolated system of energies, whatever changes or transformations take place among them, so long as no external agent intervenes, the sum of the energies will always remain constant. The Principle of Law of the Conservation of Energy has been thus formulated by Clerk Maxwell: "The total energy of any body or system of bodies is a quantity which can neither be increased nor diminished by any mutual action of these bodies, though it may be transformed into any other forms of which energy is susceptible" (Theory of Heat, p. 93). Thus stated, the law may be admitted to hold the position of a fundamental axiom in modern physics; the nature of the evidence for it, we shall consider later. But there is a further generalization, advancing a considerable way beyond the frontiers of positive science, which affirms that the total sum of such energy in the universe is a fixed amount "immutable in quantity from eternity to eternity" (Von Helmholtz). This is a proposition of a very different character; and to it also we shall return. But first a brief historical account of the doctrine. History The doctrine of the Conservation of Energy was long preceded by that of the Constancy of Matter. This was held vaguely as a metaphysical postulate by the ancient materialists and positively formulated as a philosophical principle by Telesius, Galileo, and Francis Bacon. Descartes assumed in a somewhat similar a priori fashion that the total amount of motion (MV) in the universe is fixed—certam tamen et determinatam habet quantitatem (Princip. Philos., II, 36). B...