Law of Conservation of Energy and Matter

THE LAW OF CONSERVATION OF ENERGY AND MATTER, two closely related and very similar in content laws, lying at the foundation of all exact natural science. These laws have a purely quantitative character and are experimental laws. --The Law (principle) of conservation of energy. Energy is the capacity to do work. Every body possessing energy is capable of producing only a certain amount of work, equivalent to it. Conversely, as a result of expended work, an equivalent amount of some kind of energy is obtained. Quantities of energy of different kinds that are equivalent are called quantities capable of producing the same work. The law of conservation of energy states that energy does not disappear or arise anew, but that energy of one kind can transform into an equivalent quantity of energy of another kind. The law of conservation of energy can be formulated as follows: in an isolated system the sum of energy remains always unchanged. An isolated system is one that cannot give energy outwards nor absorb it from outside; only for such a system is the law of conservation of energy valid. The law of conservation of energy, in its application to phenomena occurring with absorption or release of heat, is called the first law of thermodynamics (mechanical theory of heat). Any transition of a system open to mechanical and thermal influences from one state to another is associated with the following changes in energy: 1) heat is absorbed or released, 2) work is performed by the system or expended on it, 3) the total amount of energy contained in the system decreases or increases (total, internal energy of the system). The energy (U) given to the surrounding environment equals the external work performed by the system (A) reduced by the amount of heat (Q) received by the system: U = A - Q. The law of conservation of energy is an experimental law and follows from the certainty of the fact that it is impossible to construct a perpetual motion machine of the first kind, i.e., a machine working without an influx of energy in place of the expended one. Due to the interaction of all bodies of the universe, there are no perfectly isolated systems; consequently, the law of conservation of energy cannot be applied with full strictness to a real system. However, by including in the system, along with the bodies on which action is performed, and those bodies from which external actions originate, the inaccuracy can be reduced to arbitrarily small values. The law of conservation of energy has a biological origin. It was first stated by Mayer (J. R. Mayer; 1842), who arrived at it through physiological reasoning, and was fully expressed by the physicist and physiologist Helmholtz (Helmholtz; 1847). The first quantitative confirmation were the works of Joule, whose investigations on the transformation of work into heat led to the determination of the mechanical equivalent of heat (1850). The Law (principle) of conservation (constancy) of mass (matter, substance). This law is more correctly called the law of conservation of mass, not of matter, since it concerns only the quantitative side of matter—its mass. The law of conservation of mass states that the total mass of a substance remains constant during chemical and physical changes. The whole quantitative chemical analysis and synthesis can serve as its proof. The constancy of matter was asserted by the Greek philosophers (Empedocles, Democritus, Aristotle) and was recognized by scientists of the 16th–18th centuries. The law of conservation of mass was clearly formulated in 1756 by Lomonosov and received general recognition thanks to the works of Lavoisier (Lavoisier; 1770–89). Landolt (Landolt; 1908) gave an experimental proof of the law of conservation of mass; the differences he found did not exceed the maximum error of weighing ±0.030 mg. Doubts have been repeatedly expressed about the absolute accuracy of the law of conservation of mass, since with the most accurate weighings one can establish only an apparent constancy of mass. Thus, with weighing on Ramsay-Gray microbalances, a precision of up to +0.000002 mg is achievable, which however corresponds, for example, to an error of 80 billions of water molecules. At the present time, it must indeed be recognized that the law of conservation of mass is not entirely accurate. However, this inaccuracy has no practical significance, since the changes in mass associated with chemical and physical processes are so small that they lie within the limits of weighing error (for example, in the formation of a gram-molecule of water, 3.2 millionths of a mg is lost). This result follows from observations on the moving electron, which showed that the mass (m₀) of a resting body increases when the body moves relative to the observer. The greater the speed (v) of the body, the greater its mass (m); ^m₀ = m / sqrt(1 - v²/c²) where c is the speed of light. Since c = 3 * 10¹⁰ cm/sec., it is clear that at ordinary speeds (v) it is very close to zero and the mass m is practically independent of speed. The exception can be only for the fastest beta-particles of radium, the speeds of which approach c. From this it follows (since all kinds of energy can transform into one another) that energy possesses mass. The mass of a body that has given off energy E decreases by the amount Δm = E / c². If the energy E possesses mass m = E / c², then it follows from this that mass and energy are equivalent to each other and that any resting mass is identical with an enormous reserve of energy E, where E = m₀c², i.e., there is an identification of mass and energy, a fusion of the laws of conservation of mass and energy. The law of conservation of mass and energy is fully applicable in the field of biological sciences. Even Lavoisier, in his reasoning about the sources of animal heat, proceeded from the assumption that the substances burning in the organism develop as much heat as they do during oxidation outside the organism. However, much time passed before the validity of the law of conservation of mass and energy was proved by direct experiments on a living organism. For animal organisms, the validity of the law of conservation of matter and energy was proved by the experiments of Rubner (Rubner; 1889–94) and with even greater precision by the extensive investigations of Atwater, performed on animals, including man, at rest and during measurable work in a huge (5 m³) respiratory calorimeter. These experiments have irrefutably proved that food substances, when they burn in the organism, develop, if one takes into account the loss of energy leaving the organism with the constituent parts of urine and other excretions, as much heat as they do when burning outside the organism. The values obtained in Atwater's experiments differ from each other by less than 0.1%, and in the last, most accurate experiments the difference was only 0.005%. This error is smaller than the permissible error of ordinary chemical analyses (0.2%). Thus, the validity of the law of conservation of mass and energy for the animal organism can be considered proved. For plants, the same follows from the works of Pfeffer (Pfeffer) and others.