Physical sciences

“ Most people are familiar with the broad academic breakdown of the sciences into physics, chemistry, biology, geology, engineering, and mathematics. It is therefore convenient to examine the activities of scientific personnel in each of these areas, as well as medicine, with emphasis on the nuclear energy aspects of each.
Physics
The physicist is dedicated to investigating the laws that govern the universe. He explores gravity, motion, mass, energy, and the myriad interrelated ways that the world is constructed to gain an understanding of his physical surroundings. ”

“ Modern Astronomy, explains these motions on the principles of Mechanics.
The term Physics, when confined to a peculiar class of Sciences, is usually understood to exclude the Mechanical Sciences on the one side, and Chemistry on the other; and thus embraces the Secondary Mechanical and Analytico-Mechanical Sciences. But the adjective Physical applied to any science and opposed to Formal, as in Astronomy and Optics, implies those speculations in which we consider not only the Laws of Phenomena but their Causes ”

“ As a physical science, considers the earth apart from the solar system with which it is connected, and takes account of its materials and structure, and the forces that unite them. Its position in the group is about midway between mechanics and chemistry, being closely allied to other natural sciences, while its phenomena are occasionally varied by both mechanical and chemical agents. ”

“ The motions of the heavenly bodies, their laws, their causes, are among the subjects of the first division of the Mechanical Sciences; and of these sciences we formerly sketched the history, and have now endeavoured to exhibit the philosophy. If we were to take any other class of motions, their laws and causes might give rise to sciences which would be mechanical sciences in exactly the same sense in which Physical Astronomy is so. The phenomena of magnets, of electrical bodies, of galvanical apparatus, seem to form obvious materials for such sciences ”

“ In mechanics we should be led to analogous conclusions, and should see that the principles of this science, though more directly based on experiment, still partake of the conventional character of the geometric postulates. Thus far nominalism triumphs; but now we arrive at the physical sciences, properly so called. Here the scene changes; we meet another sort of hypotheses and we see their fertility. Without doubt, at first blush, the theories seem to us fragile, and the history of science proves to us how ephemeral they are; ”

“ Sound; Heat and physical chemistry; Electricity and magnetism; Light. Bibliography and index follow.
“The book is a valuable epitome, and should be of special service to students of physics, chemistry, and engineering.”
“Dr Edwin P. Northrup of Princeton has done a very useful service in adding to existing reference books his ‘Laws of physical science.’”
“Students of engineering and the physical sciences have long needed a compact handbook of the established propositions of physical science. Dr Northrup has prepared just such a handbook. ... ”

“ Physicists like to think that all you have to do is say, ‘These are the conditions, now what happens next?’ But all our sister sciences have a completely different problem: in fact all the other things that are studied – history, geology, astronomical history – have a problem of this other kind. ”

“ It is now believed, and to a large extent demonstrated, that the force, apparently lost, has been transformed into heat, electricity, or some other kind of molecular motion, of which the change of shape is only the outward sign. The establishment on a firm foundation of theory and experiment of the so-called conservation of energy, the child of the correlation of physical forces, is one of the first fruits of molecular mechanics. ”

“ Physics and chemistry walk hand in hand. Scientists cannot cut the tie that joins them together in experimental science. Physics treats of the changes of matter without regard to its internal constitution. The laws of gravitation and cohesion belong to physical science. They concern matter without reference to its composition. Chemistry makes us acquainted with the constituents of the different forms of matter, their proportions and the changes which they are capable of bringing about in each other. ”

“ Physical science is one and indivisible. Although, for practical purposes, it is convenient to mark it out into the primary regions of Physics, Chemistry, and Biology, and to subdivide these into subordinate provinces, yet the method of investigation and the ultimate object of the physical inquirer are everywhere the same. ”

“ From what precedes, it results that a quantity of mechanical action and a quantity of heat passing from a hot to a cold body, are quantities of the same nature, and that it is possible to substitute the one for the other reciprocally; in the same manner as in mechanics a body falling from a certain height, and a mass endowed with a certain velocity, are quantities of the same order, and can be transformed one into the other by physical agents. ”

“ This ideal has often played an effective part in popular lectures, but in the workshop of the serious inquirer it has discharged scarcely the least function. What has really been achieved in mechanical physics is either the elucidation of physical processes by more [Pg 160] familiar mechanical analogies, (for example, the theories of light and of electricity,) or the exact quantitative ascertainment of the connexion of mechanical processes with other physical processes, for example, the results of thermodynamics. ”

“ The lectures in physical science embrace nine lectures on the general properties of bodies; heat, climate, electricity, magnetism, galvanism, electro-magnetism, acoustics.
There are twelve lectures in chemistry; on water, atmospheric air, combustibles, gas, principal salts, saltpetre, metallurgy, organic chemistry. ”

“ For this reason mechanics, which treats of motion, forms the fundamental science of natural philosophy, and all other sciences endeavour to reduce the phenomena with which they are concerned to mechanical principles. Astronomy was the first to take to this path of reasoning, and succeeded in many cases in reducing astronomical to purely mechanical phenomena. Chemistry and physics, physiology and biology are proceeding in the same direction. ”

“ Physics has experienced an equally important development. It, too, at the beginning of the nineteenth century was in the preliminary state of collecting, coördinating, and trying to interpret data. In a century physics has, by experimentation and the application of mathematics to its problems, been organized into a number of exceedingly important sciences. In dynamics, heat, light, and particularly in electricity, discoveries and extension of previous knowledge of the most far-reaching significance have been made. ”

“ You are in the prime of life, in the beginning of your career, and you have powers and acquirements capable of illustrating and extending every branch of physical enquiry; and, in the field of science, how many are the spots not yet cultivated! Where the laws of sensible become connected with those of insensible motions, the mechanical with the chemical phenomena, how little is known! In electricity, magnetism, in the relations of crystallized forms to the weight of the elements of bodies, what a number of curious and important objects of research! ”

“ Is it not fully as important that, in our physical laboratories, we should organize our routine work, and provide some great generalizer, like Sir Isaac Newton, with sufficient data of electro-motive force, or, as I prefer to call it, the relations of superficial energy, in order that the relations between this energy and the ultimate motions of the molecular worlds may become better known to us? ”

“ When all these great truths respecting molar motion, or the movements of visible and tangible masses, had been shown to hold good not only of terrestrial bodies, but of all those which constitute the visible universe, and the movements of the macrocosm had thus been expressed by a general mechanical theory, there remained a vast number of phenomena, such as those of light, heat, electricity, magnetism, and those of the physical and chemical changes, which do not involve molar motion. ”

“ It may be added that the temperature, electric condition, pressure, state of motion, chemical qualities, and all other circumstances concerning matter, except its mass, are indifferent as regards its gravitating power.
As natural science progresses, physicists gain a kind of insight and tact in judging what qualities of a substance are likely to be concerned in any class of phenomena. The physical astronomer treats matter in one point of view, the chemist in another, and the students of physical optics, sound, mechanics, electricity, &c., make a fair division of the qualities among them. ”

“ To emphasize the importance of a solid grounding in basic physical principles, we have tried to have our problems touch on most of the general 40 areas of physics: mechanics, heat, sound, light, electricity and magnetism, electronics, the properties of matter, atomic physics, physics of the solid state. ”

“ New and important theoretical views of science have been reached in all departments. Recent chemistry, for instance, is a very different thing from the chemistry of a century ago. Geology has been largely transformed within the century. Heat, once supposed to be a substance, is now known to be a motion; light, formerly thought to be a direct motion of particles, is now believed to be a wave motion; new and important conceptions have been reached concerning electricity and magnetism; and our knowledge of the various sciences that have to do with the world of life is extraordinarily advanced. ”

“ The various branches of physical science differ in the extent to which at any given moment of their history, observation on the one hand, or ratiocination on the other, is their more obvious feature, but in no other way, and nothing can be more incorrect than the assumption one sometimes meets with, that physics has one method, chemistry another, and biology a third. ”

“ The principles of the science of mechanics, the only example yet existing of a complete physical theory, are altogether formed from the data of experience by the abstractive method. The class of objects to which the science of mechanics relates,—viz.,—material bodies,—are defined by means of those sensible properties which they all possess, viz., the property of occupying space, and that of resisting change of motion. The two classes of phenomena to which the science of mechanics relates are distinguished by two words, motion and force ”

“ Every form, whether inorganic or organic, which we can discover within the limits of human search, is composed of atoms, which are capable of assuming, under the influence of certain physical forces, conditions essential to the physical state of that body of which they constitute a part. [1] The known forces, active in pro [Pg 5] ducing these conditions, are modes of motion; gravitation and aggregation, heat, light; and associated with these, actinism or chemical radiation; electricity, under all its conditions, whether static or dynamic ”

“ Having aided the student in choosing his apparatus or constructing it, and given him some insight into the secrets of physical manipulation, the author, in the second part of the book, gives directions for making experiments illustrative of the principal laws of physics, as the equilibrium of forces, motion, acoustics, light, magnetism, heat, etc. The work appears to be very well adapted to meet the wants of the reader for whom it is intended. ”

“ From these considerations it must be evident that the usefulness of the physical laboratory can not be inferred from the benefits derived from the laboratory teaching of chemistry, but must be judged by a scale of values peculiarly its own. We have called physics an exact science. ”

“ The influence which forces have upon the form, state, arrangement, and motions of material substances is the principal object of physical science. In its strict sense, Mechanics is a term of very extensive signification. According to the more popular usage, however, it has been generally applied to that part of physical science which includes the investigation of the phenomena of motion and rest, pressure and other effects developed by the mutual action of solid masses. ”

“ But our usual scientific custom of interpreting hidden molecular events after the analogy of visible massive ones enables us to frame easily an abstract and general scheme of processes which the physical changes in question may be like. And when once the possibility of some kind of mechanical interpretation is established, Mechanical Science, in her present mood, will not hesitate to set her brand of ownership upon the matter, feeling sure that it is only a question of time when the exact mechanical explanation of the case shall be found out. ”

“ Finally the methods of physics have invaded a new domain, that of chemistry; physical chemistry is born. It is still very young, but we already see that it will enable us to connect such phenomena as electrolysis, osmosis, and the motions of ions. ”

“ On the remaining pages of this paper I desire to direct attention to some of the facts connected with the main subject of my present inquiry—the concept force.
Physical forces are distributed by modern science into two classes, molecular and molar forces. Molecular forces are those which determine the internal changes of a body, while molar forces cause the motion of the entire mass. ”