Dualistic/ Companion Star Hypotheses: Planetesimal and Tidal Hypothesis Explaination

 

Dualistic Hypotheses of the Origin of the Solar System

• Unlike the Monistic Hypotheses (Kant and Laplace), which assumed that the Sun and planets originated from a single primordial source, the Dualistic Hypotheses proposed that the Solar System formed through the interaction of two celestial bodies.

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For a better contextual understanding of these two upcoming hypotheses, let's understand the

"Hypothetical Variable or Assumption Method"

• Before discussing the two upcoming hypotheses, it is important to understand one of the commonly used techniques in mathematics and scientific reasoning, known as the Hypothetical Variable or Assumption Method.

• In this method, we temporarily assume the existence of a value, condition, or statement, even though it has not yet been proven.
• At this point, an important question arises:
• If something is in a state of non-existence, why do we need it to solve a mystery or achieve a desired objective?
• The answer lies in the fact that an assumption helps us simplify a complex problem and allows us to proceed logically toward a possible solution or explanation.
• The primary purposes of this technique are to:

1. Simplify complex problems,
2. Develop logical arguments,
3. Establish mathematical proofs,
4. Build scientific models.

• By using this temporary assumption tool, we explore its consequences and determine whether the resulting conclusions are logically consistent.
• However, an important caveat must always be remembered: An assumption is not a fact.

• It remains hypothetical until it is subjected to verification through mathematical proof, logical analysis, observation, or experimental evidence.
• Therefore, the assumption method serves as a powerful tool for developing ideas and theories. Nevertheless, its conclusions must ultimately be tested and validated before they can be accepted as scientifically reliable.

Application to the Upcoming Hypotheses

• The two upcoming hypotheses-

1. Planetesimal hypothesis, and
2. Tidal Hypothesis

• are fundamentally based on this Hypothetical Variable or Assumption Method, where the principal assumption is the existence of a "pre-existing companion star". 
• Using this hypothetical variable, both hypotheses attempt to explain the origin and development of the Solar System.
• However, as we have already discussed, while the assumption method is a powerful tool for developing ideas and theories, its conclusions must ultimately pass the tests of validation and verification before they can gain scientific acceptance.
• It is precisely at this stage that criticism becomes important. The criticisms of these hypotheses help us evaluate whether their assumptions can withstand scientific scrutiny. 
• As we shall see, the major challenge for these theories lies in their inability to adequately satisfy the standards of verification and validation, making it difficult for them to sustain long-term scientific acceptance.
• So, let's start with the first hypothesis.

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Planetesimal Hypothesis

(T.C. Chamberlin and F.R. Moulton, 1905)

Basic Idea

According to Chamberlin and Moulton:

1. The Sun already existed as an independent star.
2. This theory is categorised as a "dualistic hypothesis" because with the sun, there was a "pre-existing companion" massive star that passed relatively close to the Sun.
3. Because the size was larger than sun so mass generated a gravitational attraction/pull of the passing star applied on the Sun, as a result, it pulled streams of gaseous material from the Sun.
4. This pulled material turned into detached material, as it was not combined or assimilated into the passing star, because, during this duration of detachment, the companion star continued its orbital motion through space and so moved ahead.
5. The expelled/detached material gradually cooled and condensed into numerous small solid bodies called "planetesimals."
6. Through repeated collisions and accretion, these planetesimals combined to form the planets of the Solar System.

Thus, according to this hypothesis:

Flow Chart of  PLANETESIMAL HYPOTHESIS

Criticism of the Planetesimal Hypothesis

Probability Problem

• The close passage of two stars is an extremely rare event in the universe.

Temperature Problem

• Material pulled from the Sun would have been extremely hot and diffuse, making condensation into planetesimals difficult.

Angular Momentum Problem

• The hypothesis could not satisfactorily explain the present distribution of angular momentum within the Solar System.

Composition Problem

• The differences in composition between the Sun and planets remained insufficiently explained.

 

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Tidal Hypothesis

(James Jeans and Harold Jeffreys, 1917)

Basic Idea

• The Tidal Hypothesis retained the concept of a "close stellar encounter," as the main points were same as of chamberlain but proposed a different mechanism.

• According to Jeans and Jeffreys:

1. A "pre-existing companion star" with the Sun already existed.
2. That pre-existing massive star passed close to the Sun.
3. The gravitational pull of the passing star generated enormous tidal forces on the Sun.
4. These tidal forces drew out a long, cigar-shaped or filament-like stream of solar material.
5. The detached filament broke into several fragments.
6. These fragments cooled, condensed, and eventually formed the planets.

Thus:

Flow Chart of TIDAL HYPOTHESIS

Criticism of the Tidal Hypothesis

Condensation Problem

• Modern physics suggests that extremely hot solar material would disperse rather than condense into planets.

Probability Problem

• A close stellar encounter remains highly unlikely.

Angular Momentum Problem

• The hypothesis failed to explain the present distribution of angular momentum.

Composition Problem

• It did not adequately explain the differences between the Sun and the planets, with respect to structure and composition.

• This hypothesis, like the previous one, failed to explain why only 9 planets are formed.

Planet Formation Difficulty

• The detached filament would be unstable and unlikely to condense into separate planets as proposed.

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Conclusion

• Both the Planetesimal Hypothesis and the Tidal Hypothesis were important attempts to explain the origin of the Solar System through interactions between two stars. At present, this is also true in advanced astrophysics, that the proposed mechanisms were physically improbable and unable to explain several observed characteristics of the Solar System. At the same time, this is also an established fact; these dualistic hypotheses were largely replaced by modern nebular and protoplanetary disk models of planetary formation, but, still, if we are studying these, they certainly must have relevance in contextual understanding, where somebody from the forefront dared and tried to explain the mystery of the formation of the solar system, for betterment of civilisational understanding, to which modern science still exploring to complete answer.

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