What is the Big Bang? | Religion, Philosophy & Ethics for GCSE/IGCSE - Year 11 PDF Download

Introduction

The origin of the universe remains a topic of debate between scientific and religious perspectives. While scientists advocate for the Big Bang theory as the explanation for the universe's inception, some religious individuals adhere to their sacred texts, asserting that God created the universe. Similarly, scientific theories of evolution account for the development of complex life over millions of years, whereas certain religious beliefs maintain that God created all living creatures, with humans descending directly from Adam and Eve. Non-religious individuals typically rely on scientific explanations, proposing that the universe emerged by chance.

The Big Bang Theory

The Big Bang theory is the leading cosmological model explaining the universe's origin. It posits that approximately 8 billion years ago, the universe began with a massive expansion of matter and energy. 
Key points include:

• Initial State: All matter in the universe was compressed into an extremely small, dense point.
• Explosion and Expansion: A tremendous explosion triggered the rapid expansion of this matter.
• Formation of Celestial Bodies: As the expansion slowed, gravitational forces caused matter to coalesce, forming stars and planets.
• Development on Earth: Earth's atmosphere formed, enabling the growth of plants and the evolution of life from a primordial soup, starting with simple single-celled organisms that eventually gave rise to all life forms, including humans.
• Ongoing Expansion: Scientists believe the universe continues to expand, supported by phenomena such as the Red Shift.
• Supporting Evidence: Cosmic Microwave Background Radiation (CMB) is considered evidence of the residual heat from the Big Bang.

Scientific Evidence for the Big Bang

The Red Shift

The Red Shift provides significant evidence for the Big Bang and the universe's expansion. 
Key details include:

• Discovery: In 1929, Edwin Hubble observed that the universe is expanding, noting that most galaxies are moving away from our own.
• Observation of Light: Light from distant galaxies differs from sunlight, with astronomers noting an increase in wavelength.
• Spectral Shift: The dark lines in the spectra of distant galaxies shift toward the red end of the spectrum, indicating longer wavelengths.
• Implication: This shift, termed the Red Shift, suggests that these galaxies are receding, supporting the idea of an expanding universe.

Cosmic Microwave Background Radiation

Cosmic Microwave Background Radiation (CMB) further corroborates the Big Bang theory. 
Important aspects include:

• Early Universe Conditions: The theory predicts that the early universe was extremely hot and filled with radiation.
• Radiation Release: As the universe expanded and cooled, it released radiation, which is now observed as CMB.
• Characteristics of CMB: CMB appears as a faint glow of light permeating the universe, representing the oldest light detectable, originating over 14 billion years ago, before the formation of Earth or our galaxy.
• Significance: This light is considered the residual heat from the universe's inception, often described as the afterglow of the Big Bang, reinforcing the theory's validity.