Immanuel Kant

Universal Natural History and Theory of Heaven

Second Part

Concerning the first condition of Nature, the development of the celestial bodies, the causes of their movement and their systematic interrelationship both with the structure of particular planets and also with the entire creation.

See plastic Nature working to this end,
The single atoms each to other tend,
Attract, attracted to, the next in place
Form's and impell'd, its neighbour to embrace.
See Matter next, with various life endu'd
Press to one centre still, the gen'ral Good.
Pope

Section One

Concerning the Origin of the Planetary World Structure in General and the Causes of Its Movements

So far as concerns the reciprocal relationships which the parts of the cosmic structure have among themselves and through which they reveal their original cause, observation of this arrangement displays two aspects, both of which are equally probable and worthy of consideration. On the one hand, if we think of the fact that six planets with ten companions describe orbits with the sun at the mid-point, that all move in the same direction, the very same as the axial rotational of the sun itself, which governs all their orbits though the power of attraction, that their orbits do not deviate far from a common plane, namely, the extrapolated equatorial plane of the sun, that among the furthest celestial bodies belonging to the solar system, in the region where the common cause of movement was, according to our hypothesis, not so strong as in the regions close to the mid-point, deviations from the precision of this condition occur, which are significantly related to the lack of impressed motion, if, I say, we consider all this interconnection, then we will come to believe that one cause, whatever it may be, had a pervasive influence throughout the entire system and that the conformity in the direction and position of the planetary orbits is a consequence of a harmony which they must have had with that material cause through which they were set in motion.

On the other hand, if we consider the space in which the planets of our system orbit, then we find it is completely empty and deprived of all material stuff which could have subjected these celestial bodies to a common set of influences and brought harmony to their movements. This emptiness has been established with more perfect certainty and is possibly more likely than the previous condition. Swayed by this matter, Newton could not point to any material cause which must maintain by its extension into the space of the planetary system the commonality of movements. He maintained that the unmediated hand of God had set up this order without the use of any natural forces.

Considering the matter impartially, we see that the reasons here on both sides are equally strong. And they have an equal value as completely certain. However, it is also just as clear that there must be an theory which can and should unite these two apparently widely conflicting reasons and that in this theory we must seek the true system. We wish briefly to indicate that theory. In the present arrangement of space, in which the spheres of all the planetary system move around, there is no material cause present which could impress itself on or govern their movements. This space is completely empty, or at least as good as empty. Thus it must have in earlier times been differently constituted and full of matter capable of conferring movement on all the celestial bodies located there and of bringing them into harmony with its motion and, as a consequence, into harmony with each other. When the power of attraction brought unity to all of space and collected all the scattered matter in particular clusters, the planets must have then freely and unchangingly continued the orbital movement, once impressed upon them, in an unresisting space. The reasons for the first-mentioned probability absolutely require this notion . And since there is no third possibility between the two, we can approve this concept as superior, so that it can be given a higher status than a plausible hypothesis. If we wished to be long winded, we could, with a series of successive inferences in the manner of a mathematical demonstration, with all the display that this involves and with an even greater plausibility than its introduction in physical subjects customarily elicits, finally arrive at the proposal itself, which I will set down concerning the origin of the cosmic structure. But I would rather present my opinions in the form of a hypothesis and leave it to the reader's insight to put it to the test, than render its validity suspect because of the appearance of a devious demonstration, something which might captivate the ignorant but lose the approval of those who understand.

I assume that all the matter making up the spheres belonging to our solar system, all the planets and comets, at the origin of all things was broken down into elementary basic material filling the entire space of the cosmic structure around which these bodies now move. If we consider this state of nature in and of itself, without reference to a system, it seems to be only the simplest which can follow upon nothing. At that time nothing had yet developed. The incorporation of heavenly bodies separate from one another, with their distance from each other controlled according to the power of attraction, and their shape, arising from the equilibrium of the collected materials, are a later condition. Nature, on the immediate edge of creation, was as raw and undeveloped as possible. Only in the essential properties of the elements which made up the chaos can we perceive the sign of that perfection which nature has from its origin, since its being is a consequence arising from the eternal idea of the Divine Understanding. The simplest and most universal characteristics, apparently designed without purpose, had in their most rudimentary state an impulse to develop to perfection by natural means the material stuff, which apparently was merely passive and lacking form and organization. The difference in the types of elements by itself led to the movement of nature and to the development of chaos in the most noble manner, so that the tranquillity which would have ruled with a universal calm throughout the scattered elements disappeared, and the chaos began to develop itself at points where the particles had a stronger power of attraction. The types of this basic material are undoubtedly infinitely different to match the immeasurable size which nature displays in every direction. The materials with the greatest specific density and power of attraction, which by themselves take up less room and are also rarer, were then more scattered in space than the lighter varieties of material. Elements with a specific density one thousand times greater are a thousand, perhaps a million, times more scattered than those with a lighter mass. These differences must be imagined as infinite as possible. One sort of physical component can exceed another in density in the same way that a sphere drawn with the radius of the planetary system exceeds another sphere with the diameter of the thousandth part of a line. Thus, the heavier sort of dispersed elements will be much further from each other than the lighter ones.

The universal tranquillity in space replete in this way lasts only for an instant. The elements have inherent forces which set each other in motion and are, indeed, themselves, an origin of life. The material is under an immediate impulse to develop. The denser type of scattered materials, through the power of attraction, collect from a spherical area around them all the material with a lesser specific gravity. These materials, together with the stuff which they have united with them, are assembled in the points where the small pieces of an even denser type are located, and these again to even denser points, and so on. When we think about this idea of a self-developing nature throughout the entire extent of chaos, we will easily see that all the consequences of this process will finally consist of the assembling of different clusters, which, according to the way in which they developed, would be calm and eternally motionless because of the equilibrium in the force of attraction.

But nature has still other forces in store, which manifest themselves especially when the material is dispersed in fine particles, so that these particles repel each other and by their conflict with the power of attraction induce movement, which is, as it were, the enduring life of nature. This force of repulsion reveals itself in the elastic nature of vapours and the diffusion of all gasses and from objects with a strong smell. It is an uncontested feature of nature. Because of it, the elements sinking towards the point of attraction will move each other sideways from their vertical movement, and the straight linear descent will end up as an orbital movement with the point towards which they were sinking at the centre. In order clearly to grasp the development of the cosmic structure, we want to limit our observation of the infinite essence of nature to a particular system, similar to the one to which our sun belongs. Once we have explored the development of this system, then we will be able to proceed in a similar way to the origin of the higher world order and bring together into one theory the infinite nature of the entire creation.

Thus, when a point is located in a very large space where the power of attraction of the elements placed there exerts a stronger influence than at any other points around it, then the basic material stuff of elementary particles in all the surrounding area will sink to this point. The first effect of this general sinking is the development of a body at the mid-point of the forces of attraction which, so to speak, proceeds to grow from an infinitely small seed in rapid stages. As this mass increases, it will, in exactly the same proportion, through its more powerful force move the surrounding particles to unite with it. When the mass of this central body has grown so extensive that the velocity with which it draws the small particles to itself from great distances is diverted sideways by the weak level of the force of repulsion with which these particles interfere with one another, it produces lateral movements, which, thanks to the centrifugal force, are such that they move in a circle around the central body. Thus, large eddies of particles develop, each of which, because of the combination of the force of attraction and the force leading to a sideways rotation describes its own curving path. These sorts of circles all intersect each other, as a result of their large scattering in this space. Meanwhile, these movements, in various ways in conflict with each other, strive naturally to bring each other into equilibrium, that is, into a single state where the movement of one hinders the movement of another as little as possible. This occurs, firstly, because the small particles limit the movement of other particles until they all are moving forward in one direction; second, because the particles restrict their vertical movement, which brings them closer to the centre of the attraction, until the time when they are all moving horizontally, that is, in circles running parallel around the sun at the mid-point. At this stage, they no longer intersect with one another. They maintain constant free circular orbits at the heights where they are suspended, thanks to the equilibrium between the projectile force (centrifugal force) and the force drawing them downwards (centripetal force). Thus, finally only those particles remain suspended in celestial space which have attained through their fall a velocity and through the resistance of other particles a direction by means of which they can continue a free circular movement. In this condition, where all the small particles run around the central body in one direction and in circles arranged in parallel, namely, in free circular movements by means of the required projectile force, the conflict and the collision of the elements disappear. Everything is in the condition of the smallest reciprocal interaction. This result always occurs naturally with materials subject to conflicting movements. It is also clear that from the scattered number of particles a large number must, on account of the resistance through which they seek to bring each other to this state, succeed in attaining such an exact arrangement, although a much greater number do not reach this condition and serve only to increase the cluster of the central body, into which they sink, since they cannot maintain themselves freely at the height where they are suspended, but intersect the circles of the lower particles and eventually through the resistance lose all their movement. Consequently, because of the amount of its assembled material, this body at the mid-point of the attraction will become the main piece of the planetary structure. This is the sun, although at this time it does not yet immediately have that flaming glow, which breaks out on its surface when its development is fully complete.

We must also observe that while all the elements of self-developing Nature, as demonstrated, move in one direction around the sun as the mid-point, in the case of such orbits which are set up in a single direction and which occur, so to speak, around a common axis, the rotation of fine material cannot remain in this way, because, according to the laws of the centripetal force, all orbital movements must intersect the mid-point of the force of attraction with the plane of their rotation. Among all these orbits moving in one direction around a common axis, however, there is only one which intersects the mid-point of the sun. Thus, all the material from both side of this imagined axis moves quickly to that circle which goes directly through the axis of rotation at the central point of the common downward movement. This circle is the plane of movement for all the elements orbiting around; as much as possible they accumulate there and, by contrast, leave the regions far away from this plane empty. Those elements which cannot approach so closely to this plane towards which everything is drawn will not be able to maintain themselves indefinitely in those place where they are suspended, but, as they collide with the orbiting elements, will initiate their own fall toward the sun.

If we also consider this fundamental material of the planets whirling about in a state where it develops itself through the power of attraction and the mechanical consequence of the general law of repulsion, then we see a space which is contained between two planes standing not far from each other. In the middle of these planes is located the common interconnecting plane, extending from the mid-point of the sun out to an unknown extent. All the particles we can conceive have their mathematically precise circular orbits on this common plane, each proportional to the extent of its distance and to the force of attraction which governs there. Because in such an arrangement they interfere with each other as little as possible, they would remain in this form for ever, if the force of attraction of these particles of basic matter did not then start to have an effect and initiate developments, thus producing the seeds of planets which are to arise. For as the elements moving around the sun in parallel circles take up positions where the distances from the sun are not very different, circles which, because of the equality in the parallel movements, are almost in relative calm in relation to each other, then the force of elements there with an excessive specific power of attraction begins at once a significant process of collecting the nearest particles for the development of a body. As the mass of its growing cluster increases, the power of attraction of this body expands, and elements from a wide area move to combine with it.

In this system, the development of the planets has this advantage over any other theoretical possibility: the cause of the masses provides simultaneously the cause of the motion and the position of the orbits at the same moment in time. Indeed, even the deviations from the greatest precision in this arrangement, as well as the harmonies, are illuminated. The planets are developed out of particles, which at the heights where they are suspended have precise movements in circular orbits. Thus, the masses formed by their combination will continue exactly the same movement at the same level and in exactly the same direction. This is sufficient to understand why the paths of the planets are approximately circular and why their orbits are on a single plane. Moreover, they would be exactly circular if the distance from which the elements gather in their development were very small and also if the differences in their movements were very insignificant. But because the development of a thick planetary cluster involves a wider surrounding area, throughout which the fine basic stuff is scattered in celestial space, the difference in the distances of these elements from the sun and thus, in addition, the difference in their velocities is no longer insignificant. As a result, given this distance in the movements, it would be necessary, in order to maintain on the planet an equilibrium between the centripetal forces and the circular velocity, for the particles which collide with the planet from different distances and with different velocities mutually to offset each other's aberrations. Although this occurs fairly accurately, it is not perfect, and brings the deviations from circular movement and eccentricity with it. Similarly it is easy to see that although the orbits of all planets should properly be in one plane, nevertheless here also we will come across a small deviation, because, as already discussed, the elementary particles located as close as possible to the general plane of movement nevertheless take up some space on either side. It would be a really fortunate coincidence if all the planets should begin to develop exactly half way between these two sides on the plane connecting them, which would already cause some inclination of their orbits relative to each other, although the impulse of the particles from both sides restricts this deviation as much as possible, allowing it only within narrow limits. Moreover, we should not wonder about the fact that here we rarely come across the most precise accuracy in the arrangements, as is the case with all natural things, because generally the multiplicity of circumstances involved in every natural condition does not permit an exact regularity.