GASEOUS HYPOTHESIS OF KANT

Immanuel Kant, the Prussian philosopher, presented his gaseous hypothesis in his treatise entitled “The General Natural History and Theory of the Heavens or the Essay on the Working and Mechanical Origin of the Entire Universe on the Basis of Newtonian Laws" in 1755.

Obviously, Kant’s hypothesis was primarily based on Newton’s laws of gravitation and rotatory motion. He assumed that primordial matter (conceived as supernaturally created) was scattered in the universe. This matter consisted of small, hard and cold particles. These particles were attracted towards one another under the influence of gravitational pull.

In due course of time they began to collide against one another. The friction between these particles generated heat and the temperature of the primordial matter started rising. The collision also generated random motion in the primordial matter and angular velocity was produced.

Thus, the original cold and motionless cloud of primordial matter became a vast hot nebula. It was so vast that it extended from the sun in the centre to as far away as the orbit of the outer-most planet. The rise in temperature changed the state of primordial matter from solid to gaseous.

​The repeated collision of the particles increased random motion and angular velocity to such an extent that the nebula started rotating at a terrific speed and large amount of centrifugal force1 2 was generated. When centrifugal force became larger than the gravitation force (force towards the centre), a ring was thrown away from the equator of the nebula. This process was repeated nine times and nine rings were formed. The irregularity of the rings caused the development of cores (knots) which led to the formation of corresponding planets.

Our earth is a planet formed from one of the nine rings which got separated from the nebula. By small scale repetition of the same process, the gaseous mass of some of the planets throw away rings which became their satellites.

The remaining part of the original gaseous mass is our present sun. Thus the entire solar system comprising the sun, nine planets and their satellites came into being.

Kant was so confident about his hypothesis that he proclaimed, “Give me matter, and I will show you how to make a world of it.”

Merits of Kant's Theory

1. First theory based on gravity and motion. Kant’s theory was the first theory which is based on fundamental scientific facts such as Newton’s laws of gravity and motion.
2. Simple. Kant’s hypothesis appears to be simple and sounds more logical.
3. Trend setter. This theory provided ground for developing future ideas about the origin of the earth. For example the Nebular theory of Laplace was immensely influenced by his theory and it paved way for postulation of Laplace’s theory.​

Demerits of Kant's Theory

Although this theory was held in high esteem for about half a century, it has been criticised on the following ground :

1. Origin of primordial matter not explained. The basic assumption on which Kant based his hypothesis was that there was primordial matter in the universe. He has not explained the source of origin of the primordial matter.
2. Problem of Gravitational Pull. According to Kant’s view, the collision between the particles of the primordial matter was due to gravitational pull. Scientists have asked whether this force did not exist before the collision, and if it existed, what prevented it to act and collision to take place.
3. Generation of angular momentum not explained. Kant did not explain how angular momentum was generated in the primordial matter after collision of its particles. According to Newton’s first law of motion ‘a body remains at rest or in uniform motion unless and until an external force is applied on it.’ Thus, it is clear that some external force is required to generate angular momentum. Kant did not mention any such force and could not explain it satisfactorily.
4. Against the Law of Conservation of Angular Momentum. Kant assumed that rotation was set up, i.e., angular momentum was produced in the nebula by the collision of its particles. This is against the well known law of conservation of angularmomentum. In the words of Otto Schmidt, ‘‘According to law of conservation of angular momentum, the sum total of rotation in a closed system remains constant. The rotation may be transferred from one body to another, but the sum neither increases nor decreases.”