The Universe

Defining the universe and celestial bodies

Cosmology, the detailed study of the universe, covers a diverse range of celestial elements, from planets and stars to galaxies, intergalactic space, and the smallest subatomic particles. Let’s delve deeper into the intricacies of this captivating region.

Celestial bodies and astronomy

The term “celestial objects” includes stars, planets, satellites, asteroids, meteors, comets, dust, and gases. The collective presence of these celestial bodies creates the vast expanse known as the universe. Scientifically, the study of these celestial entities is aptly called astronomy, and those who delve deeper into this field are known as astronomers.

Theories about the origin of the universe

The quest to understand the origins of the universe has fascinated the human intellect throughout history. Scholars have proposed various theories, broadly classified into early theories and modern theories.

Initial Theory

Geocentric theory
– It was originated by Ptolemy in 140 AD.
– It propounds that the Earth holds an important place at the center of the universe.

Heliocentric theory
– Presented by Copernicus in 1543 AD.
– Presents the Sun as the central power in the universe.

Modern theory

Five notable modern theories attempt to unravel the mysteries of the origin and evolution of the universe.

Big bang theory
– Conceived by Georges Lemaitre in 1927.
– Tells the history of the birth of the universe from an extremely small, dense sphere (singular atom) spanning 15 billion years.

Higgs boson theory
– Groundbreaking experiments at the Large Hadron Collider (LHC) aimed to recreate conditions after the Big Bang.
– The discovery of the Higgs boson particle in 2012 confirmed the existence of the mass-providing field.

Red shift theory
The Doppler effect, which manifests itself through the red shift of light, symbolizes the rapid and accelerating expansion of the universe.

Steady state theory
– Created by Bondi, Gould and Fred Hoyle.
– Suggests a constant number of galaxies in the observable universe, with new galaxies constantly emerging.

Pulsating Theory
– Advanced by Dr. Alan Sundar.
– Visualizes the universe oscillating between expansion and contraction, creating a pulsating rhythm.

Age of the Universe

Astronomers estimate that the Big Bang occurred 12 to 14 billion years ago, with the current accepted age of the universe being 13.7 billion years. This estimate is derived from measurements of the cosmic microwave background radiation (CMBR) and observations of globular clusters. In parallel, our solar system is estimated to be 4.5 billion years old.

Fate of the Universe

The fate of the universe depends on a delicate interrelationship between the speed of expansion and the gravitational pull. Important factors include the Hubble constant and the density of the universe. If the density becomes less than the critical density, the expansion will be continuous. Conversely, high density can lead to collapse, known as the “major crisis”. A mysterious force, called dark energy, could have a significant impact on the fate of the universe, potentially ensuring its continued expansion.

In short, cosmology is a captivating journey from ancient Earth-centered theories to modern explanations of the birth and evolution of the universe. Driven by scientific curiosity and technological advancements, the quest to understand our cosmic existence continues.


1. Universe Exploration:
Cosmology sheds light on aspects ranging from planets to particles.
Astronomers observe stars, planets, and more.

2. Theories on the origin of the universe:
Ancient beliefs were centered around considering the Earth or the Sun as the center.
Modern theories (Big Bang, Higgs boson, red shift) explain the beginning of the universe.

3. Big Bang Theory:
Lemaitre’s proposal: The universe began as a small, dense ball.
Supported by evidence such as the CMBR and red shift.

4. Higgs boson theory:
LHC experiments simulate conditions after the Big Bang.
Discovery confirms a large-scale distribution area in 2012.

5. Red Shift Theory:
The Doppler effect reveals the ongoing expansion of the universe.

6. Steady State Theory:
Suggests a constant number of galaxies and that new galaxies are always being formed.

7. Flutter Principle:
The rhythmic universe proposes expansion and contraction.

8. Age of the universe:
The Big Bang was estimated to have occurred 12-14 billion years ago.
The universe is now believed to be 13.7 billion years old.
Our solar system is 4.5 billion years old.

9. Fate of the Universe:
Balance between expansion and gravity.
Hubble’s constant and density are important.
Low density results in continuous expansion; High density can lead to collapse (major crisis).
Dark energy may play a role in the continued expansion.