Sir James Jeans, a British scientist, propounded his Tidal hypothesis to explain the origin of the earth in the year 1919, while another British scientist, Harold Jeffreys, suggested modifications in the Tidal Hypothesis in 1929 and thus made it more relevant and significant. Tidal hypothesis is one of the most modern hypothesis of the origin of the earth and the solar system.
- The solar system was formed from the sun and another ‘Intruding Star’.
- In the beginning the sun was a big incandescent gaseous mass of matter.
- Besides the sun, there was another star termed as ‘ Intruding star’ in the universe. This ‘Intruding Star’ was much bigger in size than the’ Primitive Sun’.
- The ‘Primitive Sun’ was stationary and rotating on its axis.
- The ‘Intruding Star’ was moving along such a path in such a way that it was destined to come nearer to the ‘Primitive Sun’.
- There was a great impact of the tidal force of the intruding star on the surface of the ‘Primitive Sun’.
James Jeans postulated that due to massive gravitational force of the ‘intruding star’, huge amount of matter was ejected from the primitive sun, which later on became the building material of future planets. According to Newton’s law of universal gravitation every body in the universe attracts every other body with a force which is directly proportional to the product of the masses of the two bodies and inversely proportional to the square of the distance between them. It means that the intensity of the gravitational force of the ‘intruding star’ and the ‘primitive sun’ would depend upon two factors, e.g.
- Product of the masses of the ‘Intruding star’ and ‘Primitive Sun’
- The distance between the two stars.
It means if the product of the masses of the ‘Intruding Star’ and the ‘Primitive Star’ is high, the amount of gravitational force between them will also be high and if the product of masses of the two star is low the amount of gravitational force will also be low. Thus, if the mass of the intruding star is high, the gravitational force exerted by it will also be high. Since, James jeans assumed the ‘Intruding Star’ to be much bigger than the ‘Primitive Sun’, the former exerted larger amount of gravitational pull on the surface of the primitive sun than the gravitational pull of the ‘Primitive Sun’ which caused ejection of matter from the ‘Primitive sun’.
Secondly, there is an inverse relation between the gravitational force of two stars and the distance between them.
Gravitational force (α) = (1/d)
d stands for ‘distance between the Intruding Star and the Primitive Star’
It means, when the distance between two stars decreases gravitation increases, when the distance between two stars increases gravitation decreases. Since, the ‘Intruding Star’ was coming closer to the primitive star and hence the amount of gravitational force between them was also increasing.
Evolution of Filament:
According to James Jeans, the ‘Intruding Star’ was moving along such a path that it was continuously come nearer to the primitive sun and thus exerted gaseous tidal force on the outer surface of the ‘Primitive Sun’ also increase. When intruding star come nearest to the ‘Primitive Sun’, its gravitational force become maximum and thus a giant cigar shaped tide, thousand of km in length and huge masses was created on the outer surface of the primitive sun and ultimately was ejected from the primitive sun. Jeans called this cigar- shaped matter as ‘filament’, which was much thicker in the centre and thinner sharper at the eds.
The explanation of the shape of the ‘Filament’:
- When the intruding star was at distant place from the ‘primitive sun’ the gravitational attraction exerted by it on the surface of the primitive sun was also low due to greater distance between them. Thus, a small quantity of the first part of the incandescent matter came out from the surface of the ‘Primitive Sun’.
- When the ‘intruding star’ came nearest to the ‘Primitive Sun’ , maximum gravitational attraction was exerted by it on the outer surface of the primitive sun. Thus, the ejection of maximum amount of incandescent matter.
- Again, when the ‘Intruding Star’, moved away from the ‘Primitive Sun’, gravitational attraction became again minimum and thus a small amount of matter was ejected from the outer surface of the ‘Primitive Sun’. Thus, the shape of matter ejected from the ‘Primitive Sun’ became like a cigar which was called by Jeans as ‘Filament’.
- Gradually the intruding star moved far away from the ‘Primitive Sun’ and thus, went on the domain of the gravitational field over ‘Primitive Sun’. In the beginning when the filament was detached from the ‘Primitive Sun’, it followed the’ Intruding Star’, as it was pulled by the ‘Intruding Star’. The filament tried keep pace with the ‘Intruding Star’, but could not succeed and ultimately it started revolving around the ‘Primitive Sun’.
Formation of planets from the filament:
According to James Jeans nine planets our solar system were formed due to cooling and condensation of the incandescent mass of gaseous matter of the filament. The filament after being detached from the ‘Primitive Sun’, began to cool down. Thus, the filament started contracting in size on cooling. The contraction of filament led to its breaking in several pieces and each pieces was condensed to form one separate planet. This process led to the formation of nine planets.
The filament of incandescent gaseous matter allowed bigger planets to form in its middle portion and smaller ones towards its tapering end. The remaining part of the ‘Primitive Sun’ became our sun. The satellites of the planets were formed due to gravitational pull and tidal effect exerted by the sun on the outer surface of the newly formed planets.
Evidences in favour of the hypothesis:
The ‘Tidal Hypothesis’ of James Jeans has not only explained the origin of the solar system but he also should explain various problems of the solar system related to its shape, size, structure and peculiar motion. The following characteristics of the solar system are more or less explained on the basis of this hypothesis.
Shape and ordering of planets:
The filament ejected from the primitive sun was cigar- shaped. It was thick in the middle portion and thin at the ends. The planets formed from the condensation of the incandescent gaseous matter of the middle portion of the filament were in bigger size than the planets formed from the condensation of matter at the tapering ends of the filament. This arrangement of the planets formed of the filament clearly matches with the present planetary arrangement of our solar system.
Ordering and arrangement of satellite:
According to this hypothesis the satellites of the planets were formed through the condensation of incandescent gaseous matter ejected from the planets in the same manner as the planets were formed through the condensation of incandescent matter ejected from the sun. Thus, there is almost the same type of arrangement of the satellite around the planets as like as the arrangement of planets around the sun.
Rotation, revolution and inclination of the planets axis:
In our present solar system all planets are revolving around the sun in the same direction and also in the same orbital plane. Similarly, almost all their satellites of their planets are also revolving around their respective planets in the same direction as their father planets are revolving around the sun.
Number and size of satellites:
Larger number of satellites were formed from bigger planets, because, bigger planets took longer time to cooling and condensed. But, the size of the satellites of these bigger planets were relatively small, whereas fewer numbers of satellites were formed from medium planets, but, their size was relatively larger.
The tidal hypothesis as propounded by James Jeans enjoyed a long lease of popularity and wide appreciation till the end of the 1st and 20th century because of its simplicity, inherent logic and scientific appeal but the hypothesis was severely criticized on various grounds. The following criticism have been labelled against this hypothesis.
- According to B.Levin the universe is infinite in space and time and the stars are so distant from each other that such a close encounter between them is remote possibility.
- James Jeans did not explain the where about and density of the intruding star which caused tidal eruption on the surface of the primitive sun in the form of filament.
- James Jeans could not elaborate the process and mechanism of the condensation of matter ejected from the ‘Primitive Sun’.
- The planets of our solar system are largely formed of the elements having high atomic weight, but, the constituent elements of the sun are of lighter atomic weight e.g. hydrogen and helium. The tidal hypothesis fails to offer convincing explanation for such anomalous situation.
- The satellites were formed from the tidal effect exerted by the primitive sun on the newly born planets, then question arises, why no satellite was formed from mercury and Venus though these planets were nearest to the sun.
- N.N. Parisky has proved on the basis of mathematical calculation that tidal hypothesis fails to explain the real distances between the sun and the planets in our present solar system.
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