Early theories regarding the " Origin and structure of the Earth" only focused on the evolution of the solar system, but
modern theory such as the Big Bang theory tries to solve problems such as the origin of the
universe, the evolution of the solar system, the evolution of earth crust and atmosphere, etc. Big Bang theory is a modern theory and it is also called the expanding universe hypothesis; tries to solve the many questions related to the origin of the universe.
Why Big Bang theory is also called the expanding universe hypothesis theory?
Expanding Universe Hypothesis (or Theory) refers to the idea that the universe is currently expanding, meaning that galaxies are moving away from each other as time progresses.
The hypothesis of an expanding universe was initially proposed by Belgian astronomer Georges Lemaître in the early 20th century and was later confirmed through observations of the "increasing distance between galaxies" by Edwin Hubble in 1920.
Using the redshift phenomenon based on the Doppler effect.
- It has been found that light emitted from the star's wavelength is expanding over time, which means stars are going away from us.
- Scientist has discovered the cosmic wave that has the origin of the Big Bang times( that was 13.7 billion years ago). It means the universe is still expanding.
As per Big Bang theory:
Star formation as per Big Bang theory:
- All matter that formed the universe existed in one point called singularity having less than the area of the atom with unimaginable small volume, infinite temperature, and infinite density.
- It exploded with a big bang around 13.7 billion years ago.
- Within 3 minutes of the Big Bang event, the first atom was formed.
- Over time, the energy was converted into matter.
- After the formation of atomic matter, around 3 lakh years after the Big Bang, the universe became transparent.
Star formation as per Big Bang theory:
- It starts 5 billion years ago.
- According to the Big Bang Theory, the universe began as infinite heat and dense material.
- Over time, the universe expanded, due to which it began to cool down, causing the formation of preliminary elements of the universe (hydrogen and helium). These primary elements are raw materials from which the stars will eventually be formed.
- In the early universe, there was an uneven distribution of matter and energy. Due to the initial density difference, gravitational forces vary. Due to this, the substance started gathering among themselves and this collected dust particles later became the basis of the development of the galaxy. At the early time of construction, a huge cloud of hydrogen gas was formed which was called nebula. Within Nebual, many dense cores were formed which is known as a protostar. This protostar continues to accrete matter from its surroundings.
- When the temperature and pressure at the core of a protostar are significantly high, nuclear fusion begins. Hydrogen atoms fuse to make helium, releasing a tremendous amount of energy. It marks the birth of a true star. In this way, stars were formed.
- Comprises of a large number of stars.
- The formation of galaxies started from the nebula which is made up of hydrogen and helium gases.
Formation of planets:
The planets are formed within the protoplanetary disk. These disks surround the protostar ( young stars). The disk contains the remains of gas and dust from which the star is formed.
Over time, these solid particles which protoplanetary disks, collide and stick together, which form large and large objects, which are called planetesimal (infant planets). Over time, small planetesimals (infant planets) merge into large planetesimals (infant planets) due to gravitational pull. Later, full planets are formed at the end of this process.
Formation of the solar system:
In our own solar system, the sun was formed in the center, while the planets and other astronomical bodies are made of the surrounding protoplanetary discs of the Sun.
Evolution of Earth:
Within the protoplanetary disk surrounding the young Sun, solid particles began to collide and stick together, forming planetesimals. Over time, these planetesimals grew larger through accretion and collisions, ultimately forming the planets. Earth, along with the other planets in our solar system, formed from these processes.
Earth has a layered structure from the outmost atmosphere to the center of the earth. It is not uniform.
Development of lithosphere
As Earth grew, it underwent a process of differentiation, with heavier materials sinking to the core and lighter materials forming the mantle and crust. This process generated the Earth's layered structure.
These three layers are:
- Crust
- Mantle
- Core
Evolution of atmosphere and hydrosphere
The present atmosphere is made by three stages:First stages:
Loss of primordial atmospheres such as helium and hydrogen blew off by solar winds.
The hot interior of the earth contributed to the evolution of the atmosphere. During the cooling, gases, and water vapor from the interior of the earth came out into the atmosphere. At this stage, the atmosphere is largely comprised of water vapor, nitrogen, carbon dioxide, methane, ammonia, and very little free oxygen. This process is called degassing.
Third stage:
The composition of the atmosphere was modified by living organisms through photosynthesis and oxygen began to flood the atmosphere.
Carbon dioxide in the atmosphere gets dissolved in rainwater and further decreases causing more condensation and more rain.
Origin of life:
The origin of life is a kind of chemical reaction. It came from inorganic materials. Life began to evolve, 3800 million years ago from blue algae.The conditions on Earth, such as the presence of liquid water and a stable climate, made it conducive for the emergence and evolution of life.
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