Mysterious origin of Earth is explained by the early theories of “Gaseous Hypothesis of Kant”, “Jean and Jeffery’s Tidal or Gravitational Theory”, “The Nebular Hypothesis of Laplace”, “Hoyle’s Supernova Hypothesis”, “Schmidt’s Interstellar Hypothesis”, “The Planetesimal Hypothesis of Chamberlin” and Binary Theory or Planetesimal Hypothesis of Chamberlin. Big Bang Theory is also one of the most accepted theory related to origin of earth. While these early ideas offered fundamental insights into Earth's formation and laid the groundwork for understanding our planet's origins but were not without their challenges and debates among researchers providing a comprehensive overview of Earth's extraordinary genesis in the realm of Geomorphology which is an important part of the UPSC exam geography syllabus.

Theories of Origin of Earth

Theories for the earth's origin has been classified into two categories i.e., early theories and modern theory which are as follows:

• Early Theories: Early Theories explained how the earth was formed. The early theories were the Gaseous hypothesis of Kant, the Nebular Hypothesis of Laplace, the Planetesimal hypothesis of Chamberlin, Jean and Jeffery's tidal theory/Gravitational Theory, Russel's binary star hypothesis, Hoyle's supernova hypothesis, Schmidt's interstellar hypothesis.
• Modern Theories: Modern theories state the need to find how the universe has formed then automatically we will be able to find the formation of the earth.
  • Early theories focused solely on the evolution of the earth and planets, whereas recent theories attempt to solve the questions of the universe's creation.
  • Big Bang theory is an example of modern theory.

The Gaseous Hypothesis of Kant

• Immanuel Kant, a German philosopher, proposed his own theory regarding the origin of the earth in 1755, which was based on Newton's law of gravity.
• Kant believed that the original substance was initially distributed and was made up of cold, unmoving, solid particles.
• They clashed with each other because of gravity, which produced heat, which induced angular momentum, and it began to rotate.
• Later, it evolved into a hot nebula that began rotating, causing the speed to progressively increase.
• This rotation resulted in a strong centrifugal force, which produced rings of matter, which cooled to become planets and satellites.
• According to the widely accepted nebular hypothesis, the earth formed from a massive cloud made primarily of hydrogen and helium.
• Contraction, rotation, and lowering temperatures resulted in the formation of small particles. After tens of millions of years of condensation and accretion, these started to clump together, and the earth was created about 4.5 billion years ago.

Gaseous Hypothesis of Kant

Criticism of Kant’s Theory

• Kant claimed that the universe included primordial matter, but he did not explain where the primordial matter came from.
• Kant did not explain the source of energy that caused the random motion of the original matter particles, which were first cold and unmoving.
• It is impossible for the primordial matter's particles to collide and produce rotatory motion. It's an incorrect mechanism statement.
• Law of conservation of angular momentum: Kant believes that the rotatory speed of the nebula increased as its size grew, which contradicts the law of conservation of angular momentum.

Nebular Hypothesis of Laplace

• Kant's theory was revised in 1976 by mathematician Laplace.
• According to the nebular hypothesis, the Sun was encircled by a solar nebula made up primarily of hydrogen and helium, as well as dust.
• The development of a disk-shaped cloud is caused by particle impact and friction.
• Planets were formed from material associated with the young sun as a result of the accretion process.

Nebular Hypothesis-Origin of the Planets

Criticism of Nebular Hypothesis

• The nebula's origins are not explained by the nebula hypothesis.
• It was unable to explain the sources of nebula heat and motion.
• According to the nebular hypothesis, because the nebula is gaseous, the planet should likewise be gaseous, however, this is not the case.
• The hypothesis fails to explain how the development of solid planets is caused by house gas nebulae.
• The planets and satellites should all rotate in the same direction as the nebula, however, this isn't the case.

Binary Theory or Planetesimal Hypothesis of Chamberlin

Planetesimal Hypothesis of Chamberlin

• In 1900, Chamberlain and Moulton gave this theory.
• According to this theory, another wandering star approached the sun.
• As a result, the material's cigar-shaped extension from the solar surface was separated.
• The sun with its very high-temperature projects hot material called the prominences.
• The particles of this material got coalesced to form the planets. A lot of heat was generated in the process.
• Separated material slowly condensed into a planet as the passing star moved away, and the sun continued to spin.

Jean and Jefferys Tidal Theory/Gravitational Theory

Jean and Jeffery's tidal theory

• Jeans and Jeffrey were both scientists from the United Kingdom. To explain the formation of Earth and our solar system, they proposed the "Jeans Jeffreys Tidal Hypothesis."
• The gravitational force of two stars has resulted in the formation of our solar system.
• Primitive Sun: The primitive sun is the early stage of the sun.
• Intruding Star: In comparison to the primitive sun, it was much larger.
• When intruding stars passed close enough to the primitive sun, hot gas tides rose on it.
• Cigar-shaped hot gaseous particles were separated from the primordial sun when the intruding star was closest to it across the entire traveled distance. Jeans and Jeffrey refer to filament as cigar-shaped.
• Because the filament's central sectors were bulgy and had more gas material, bigger planets like Jupiter and Saturn were formed.
• On both sides of the filament, smaller planets were produced.

Criticism of Jean and Jeffreys Tidal Theory

• Our solar system's planets are made up of heavier atomic material, but if the planets' material is carved from the sun, it should be made up of lighter atomic material like helium and hydrogen.
• The process and mechanism of condensation were not explained.
• In the universe, stars are so far apart that there are few chances of intruding stars.
• Jean Jeffrey did not give much information about the intruding star and its origin.

Russell's Binary Star Hypothesis

Binary Star Hypothesis by Russell

• The theory propounded the existence of binary (two) stars, the bigger one of which ejected mass under the influence of a third one coming close at higher speed, leading to the formation of planets.

Criticisms of Russell's Binary Star Hypothesis

The intruding star and the remnant of the star from which stuff was ejected are not explained by Russell's binary Star Hypothesis.

Hoyle's Supernova Hypothesis

False color image of Kepler Supernova remnant from Chandra X-ray Observatory

• In 1946, Fred Hoyle proposed this theory.
• The sun used to be twinned with another star, which burst due to nuclear processes that transformed lighter components into heavier ones.
• The companion star's explosion produced a cloud of incandescent gases, which he refers to as the "Supernova stage."
• As the nucleus receded far away, the sun's gravitational power kept this gaseous cloud and the rest of the star together.
• The gaseous cloud at the supernova stage contains iron and other earth elements.
• The earth, as well as other planets and satellites, were formed from these particles.
• They revolved around the sun because they were in the sun's gravitational field, and gradually cooled to the solid form in which the planets and satellites exist today.

Schmidt's Interstellar Hypothesis

• According to this theory, the primordial dust began to coalesce into a disk-shaped configuration as it moved at a high pace.
• These disk-shaped nebulae were further subdivided into rings, each holding asteroids that eventually merged into planets.

Criticism of Schmidt's Interstellar Hypothesis

• Schmidt didn't go into detail about how these mysterious substances came to be. Schmidt dubbed these black particles "interstellar dust".

Big Bang Theory

Timeline of Big Bang Theory

• After Edwin Hubble proposed the constant expansion of the Universe, another Belgian cosmologist came up with the Big Bang Theory in 1931.
• According to the big bang theory, all of the matter that made up the universe resided in a single location with a volume smaller than an atom, an unlimited temperature, and an infinite density.
• The theory suggests that the Universe, at some point in time, was condensed into a single particle and later started expanding infinitely after a huge explosion.
• The expansion later gave birth to nebulae that in turn, coalesced into stars and planets.
• The science community unanimously agrees over the age of the Universe to be around 13.8 billion years.
• Around 3 lakh years after the big bang, the universe turned transparent due to the production of atomic matter.

Conclusion

Origin of Earth is a captivating journey spanning 4.54 billion years, shaped by early theories like Kant's Gaseous Hypothesis and Laplace's Nebular Hypothesis. As we explore diverse perspectives, from Chamberlin's Planetesimal Hypothesis to Hoyle's Supernova Hypothesis, and embrace modern theories like the Big Bang Theory, we gain profound insights into the dynamic processes that birthed our planet. Despite the criticisms, these theories collectively contribute to our understanding of Earth's remarkable evolution within the vast cosmic tapestry.