The French scientist Pier de Laplace proposed the nebula hypothesis in 1796. He described this hypothesis in his book "Exposition of the World System"
In fact Laplace's hypothesis is a modified form of Kant's hypothesis. Laplace isolated the elements on which Kant was criticized and presented this hypothesis. Kant's hypothesis had the following three drawbacks:
(1) Motion cannot be generated by the collision of primordial substances, (2) they cannot connect with each other due to collision of substances, (3) The speed of nebula cannot increase as size increases.
Laplace started his hypothesis with a dynamic nebula in the universe, with the aim of removing these criticisms. According to Laplace, there was a dynamic and aural nebula in the universe from the beginning that resembled the nectar of Kant. This nebula was slowly being cooled by radiation. This caused the upper cover of the nebula to cool down and shrink. The volume of the nebula decreased and the speed started increasing. Due to excessive speed, the Centrifugal Force was generated in its center. At the same time the upper cover could not rotate with the inner core due to cooling. Therefore, a round ring came out from the top of the nebula and started moving around the nebula. Later 9 rings came out of this ring, which went away from each other and each ring has formed different 9 planets. The material left in the nebula after the exit of this ring is the present sun.
Explaining the nebula hypothesis:
Laplace's hypothesis was given long-term importance. This is a simple hypothesis and it solves many problems related to the origin of the solar system. (1) Due to this principle, the rotation of planets on their axis and their orbit becomes clear. (2) Initially, the planets were in an aerial state and gradually cooled down. It has now been proved that the earth was hot in the beginning and gradually cooled down. This appears to be the truth in this theory. (3) All the planets of the solar system revolve on the same plane and the same direction, this also reinforces the hypothesis of Laplace. (4) All planets are formed from similar substances. A similar thing has been said in this hypothesis. (5) The nebulaes that are roaming around in the universe at this time are exactly the same as those of the nebula Laplace.
Criticism of the Nabular hypothesi
Laplace's hypothesis was given long-term importance. This is a simple hypothesis and it solves many problems related to the origin of the solar system. (1) Due to this principle, the rotation of planets on their axis and their orbit becomes clear. (2) Initially, the planets were in an aerial state and gradually cooled down. It has now been proved that the earth was hot in the beginning and gradually cooled down. This appears to be the truth in this theory. (3) All the planets of the solar system revolve on the same plane and the same direction, this also reinforces the hypothesis of Laplace. (4) All planets are formed from similar substances. A similar thing has been said in this hypothesis. (5) The nebulaes that are roaming around in the universe at this time are exactly the same as those of the nebula Laplace.
Criticism of the Nabular hypothesi
(1) According to this hypothesis, the angular Momentum of the planets and the Sun should be equal while the Sun has only 2 percent angular velocity and the remaining 98 percent is on the planets. On this basis, the hypothesis does not seem correct. (
2) According to this hypothesis, all the planets are formed by a ring coming out of the nebula and many small rings come out of it, so as the planets get away from the nebula (Sun), the size of the planets should be incident, but such Is not. In the present solar system, along with the distance from the Sun, there are first small planets, larger in the middle and then smaller. Laplace's theory is wrong on this basis.
(3) Round planets cannot be formed due to condensation of rings. In fact the ring will break into small pieces.
(4) If the planets are formed by a rotating nebula (Sun), then the Sun should rotate very fast as the size of the object increases as the size decreases. But the speed of the Sun is very low.
(5) According to this theory, planets revolve around the Sun and satellites should revolve their parent planet in a certain order. But currently there are many satellites that rotate in the opposite direction of their parent planet.
6.If the planets originate from the Sun, then all the planets should rotate in one direction .
7.According to Laplace, the sun is the residual part of the nebula, so the process of planet formation must be repeated, that is, it should rise in the middle part. But no bulge is visible on the surface of the Sun.
6.If the planets originate from the Sun, then all the planets should rotate in one direction .
7.According to Laplace, the sun is the residual part of the nebula, so the process of planet formation must be repeated, that is, it should rise in the middle part. But no bulge is visible on the surface of the Sun.
8.Laplace did not explain the origin of the Nebula in the universe.
9. The temperature and speed of the nebula have also not been clarified. How did heat and motion arise in the Nebula and where did the Nebula come from?
(10) Why only 9 rings came out of a ring emanating from the nebula, less or more of it could have come out. Laplace is not sloved with this problem. (11) By the small degree of cohesion between the particles of Nebulae, the order of release of rings will not be released if the nebula's particles continue.
Thus although the nebula hypothesis of Laplace is simple, many facts were not explained in it. Secondly, this hypothesis reveals many erroneous facts, hence this hypothesis is not recognized in modern times.
9. The temperature and speed of the nebula have also not been clarified. How did heat and motion arise in the Nebula and where did the Nebula come from?
(10) Why only 9 rings came out of a ring emanating from the nebula, less or more of it could have come out. Laplace is not sloved with this problem. (11) By the small degree of cohesion between the particles of Nebulae, the order of release of rings will not be released if the nebula's particles continue.
Thus although the nebula hypothesis of Laplace is simple, many facts were not explained in it. Secondly, this hypothesis reveals many erroneous facts, hence this hypothesis is not recognized in modern times.
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