Gravitation

“ So I sometimes have dared to dream that gravitation may be the reservoir that conserves the energy for all mundane forces, and that what we call modifications of force are intermediate conditions, ripples, rapids, or cascades, in gravitation. ”

“ You may consider these, then, as separate particles magnified, so as to be evident to your sight; they are loose from each other—they all gravitate—they all fall to the earth—for the force of gravitation never fails. Now I have here a centre of power which I will not name at present, and when these particles are placed upon it, see what an attraction they have for each other. ”

“ For instance, the law of gravitation—simplest of physical principles—holds the last star in the abyss of space, rounds the dew-drop on the petal of a spring violet and determines the symmetry of living organisms ”

“ Thus, it would be impossible to escape a duality in our conception of gravitation, if by gravitation we imply the cumulative action of both effects, yielding the one observable attraction of matter for matter. ”

“ Universal gravitation is declared to be a vast generalization, telling us that there is no more, but yet just as much, of mystery in the whole sequence of astronomical phenomena, as in the most humdrum processes of every-day experiences. ”

“ We have made comparative estimates of the weight of the earth and planets, and have reason to believe that the force expression of gravitation attains a maximum at about one-sixth the distance toward the center of the earth, then decreases, until at the very center of our planet, matter has no weight. This, together with the rule I repeated a few moments ago, is about all we know, or think we know, of gravitation. Gravitation is the beginning and gravitation is the end; all earthly bodies kneel to gravitation. ”

“ Now, the globe of the earth is a prodigious mass of matter, to which nothing near it can bear any comparison. It draws, therefore, with mighty force, everything within its reach, which is the cause of their falling: and this is called the gravitation of bodies, or what gives them weight. When I lift anything, I act contrary to this force, for which reason it seems heavy to me, and the heavier the more matter it contains, since that increases the attraction of the earth for it. ”

“ The great doctrine of gravitation and attraction, the substratum of the Newtonian philosophy, is amply verified by numerous observations and experiments. Whether that which constitutes the principle of gravity be, in itself, an incorporeal or spiritual substance, or a materia subtilis, some very subtile kind of ethereal fluid, is a question which does not at all affect the actual existence of such a power. ”

“ And just as astronomers and physicists, confining their investigations to the more obvious and perceptible motions of celestial and terrestrial bodies, long remained ignorant of the law of gravitation which constantly forces all things into a state of equilibrium, so in biology the statical condition has been lost sight of in the effort to obtain better views of that moving panorama which a broader knowledge of the phenomena of life so unmistakably unfolds. ”

“ Of course, in the pseudo-formulas of astronomers, gravitation as a fixed quantity is essential. Accept that gravitation is a variable force, and astronomers deflate, with a perceptible hissing sound, into the punctured condition of economists, biologists, meteorologists, and all the others of the humbler divinities, who can admittedly offer only insecure approximations. ”

“ On the other hand, gravitation itself—more universal than anything else in the universe—may be interpreted in terms of strains on world-lines, or, what amounts to the same thing, strains of space-time combinations. ”

“ It is in this sense, and in this sense alone, that I have used above the expressions Force and Life. Astronomers consider gravitation the unknown cause of the movement of the stars; I consider Life as the unknown cause of the phenomena which are characteristic of organised beings. It may be that both gravitation and Life, as well as the other general forces are merely as x, of which the equation has not yet been discovered. ”

“ Let us remember then that, so far as we know, it is a law of nature, that any two material bodies, if they are free to move, approach one another with gradually increasing swiftness; and that the space over which each travels before the two meet, is inversely proportional to the quantity of matter which it contains. Attraction of gravitation is a name for this general fact; weight is the name for the fact in the case of terrestrial bodies; force is a name which we give to the unknown cause of the fact. ”

“ Thus it was that the impenetrability, the mobility, and the impulsive force of bodies, and the laws of motion and of gravitation, were discovered. And to us it is enough, that gravity does really exist, and act according to the laws which we have explained, and abundantly serves to account for all the motions of the celestial bodies, and of our sea. ”

“ This becomes still more evident in gravitation. Gravitation is so decidedly an action in space, that it appears to us, together with cohesion, as precisely the bond which binds the entire material world together. ”

“ The law of gravitation is the limitation imposed upon that mysterious force which appears to reside in all matter, that it should attract all other matter. This power of attraction is called gravitation ”

“ THE explanation of gravitation has now risen to the rank of one of the foremost problems of modern science; indeed the day for the ascription of occult qualities to matter is now gone, and phenomena, demand an explanation by the reason. The ascription of an occult quality, so far from throwing light upon a phenomenon, only serves to darken it. The effects of gravity (like all other physical effects) being effects of motion, have, like other physical effects, to be explained. A rational explanation has to be given for the motion of approach of two masses. ”

“ But these apparent deviations are merely appendages to the great general law, in order that creation may be perfect in all its parts. For instance, there is a general law of what is termed gravitation which causes bodies to fall to the earth from a given height, with the same velocity according to their specific gravity. ”

“ We have, then, the same reason for supposing that air and water, in other parts of the system, are governed by universal gravitation, and exercise themselves the attractive force of gravitation, which we have for making the like suppositions with regard to the most solid bodies. ”

“ We should thus have in light a continual, visible appearing of gravitation, and it would be explained why, in the system of worlds, it is exactly those bodies which are the principal seat of gravity that are also the principal source of light. We should then, also, have an explanation of the connection in which the action of light stands to that of gravitation. ”

“ If we regard gravitation as the representative of forces that act or appear to act, at a distance, we may regard cohesion and chemical affinity as the representatives of those forces which, although very powerful, only act or appear to act through a very small interval of distance. ”

“ Beyond the facts of constant and of signal failure, these restless, resolute probings by the human mind in all directions, serve as the cumulative bases of a new induction ; and by the very sharpness of the contrasts brought to view at every point between the tentative conjecture and the determinate experience, they enforce the assurance, that whatever else the principle of gravitation may be, it is not in its essence any form of motion. ”

“ To refer the great fact of gravitation to some unimagined and unimaginable aether-motion, the special arrangements of which for effecting the desired purpose " elude research," is not to proffer an explanation, but to indulge in an illusion ”

“ There, though the weight of a given mass of matter is different from what it is with us, it is nevertheless determined by the law that determines here—the law of gravitation. There energy is indestructible, and is measured as it is measured among us, by work. Then is there any boundary that we can assign to natural law—is it not omnipresent, universal? ”

“ The following remarks upon this theory deserve our attention: "The explanation of any action between distant bodies by means of a clearly conceivable process, going on in the intervening medium, is an achievement of the highest scientific value. Of all such actions that of gravitation is the most universal and the most mysterious. ”

“ Turning from the heavens to the earth, and ignoring such primitive observations as that of the distinction between land and water, we may note that there was one great scientific law which must have forced itself upon the attention of primitive man. This is the law of universal terrestrial gravitation. The word gravitation suggests the name of Newton, and it may excite surprise to hear a knowledge of gravitation ascribed to men who preceded that philosopher by, say, twenty-five or fifty thousand years. ”

“ Propounds the theory of universal gravitation.To the force producing this tendency of bodies to approach each other the designation of attraction of gravitation, or gravity, is given. All heavy bodies fall to the earth in such a way that the direction of their movement is toward its centre. Newton proved that this is the direction in which they must necessarily move under the influence of an attraction of every one of the particles of which the earth is composed, the attraction of a sphere taking effect as if all its particles were concentrated in its centre. ”

“ Conceive the synthesis of both, and you have matter as a fluxional antecedent, which, in the very act of formation, passes into body by its gravity, and yet in all bodies it still remains as their mass, which, being exclusively calculable under the law of gravitation, gives rise, as we before observed, to the science of statics, most improperly called celestial mechanics. ”

“ We find universally distributed in nature the sensation of the mechanical stimulus of gravitation, the most comprehensive statement of which is given in Newton's law of gravity. According to this fundamental and all-ruling law, any two particles of matter are attracted in direct proportion to their mass and inverse proportion to the square of their distance. ”