Theories on The Origin of the Universe

Chapter 1: Earth's Origin

• Creationism

  • Narrative from Genesis in the Hebrew Bible and Christian Old Testament

  • Describes God creating the universe in six days

• Primordial Universe

  • Greek philosopher's belief in a primordial mixture of all ingredients in the cosmos

  • Ingredients were set in motion and separated to form the universe

• Atomic Universe

  • Greek philosophers Leucippus and Democritus believed in an atomic universe

  • Universe composed of tiny, indestructible atoms forming different combinations

• Stoic Universe

  • Stoic philosophers believed the universe is like a living body

  • Interconnected parts where events in one place affect others

• Static or Newtonian Universe

  • Isaac Newton's theory of a static, infinite universe with uniform matter distribution

• Cartesian Vortex Universe

  • Rene Descartes' model of the universe with swirling matter in vortices

  • Produced gravitational effects and convection currents

• Einsteinian Universe

  • Albert Einstein's theory of a static, dynamically stable universe

  • Added a cosmological constant to counteract gravity's dynamic effects

Modern Theories on the Origin of the Universe

• Oscillating Universe

  • Einstein's favored model with positive curvature and cycles of expansion and contraction

  • Described in the Hindu text Rigveda as a cyclical universe

• Steady State Theory

  • Predicted a universe that expanded but maintained a constant density

  • Matter inserted into the universe as it expanded

• Inflationary Model

  • Alan Guth proposed a model with exponential cosmic inflation to solve problems in the big bang model

  • Variation: cyclic model by Paul Steinhardt and Neil Turok based on superstring theory

• Multiverse

  • Andrei Linde's concept of multiple universes or "bubbles" in the multiverse

  • Hugh Everett III and Bryce Dewitt developed the "many worlds" structure of the universe

• Big Bang Theory

  • Monsignor Georges Lemaitre's theory of an expanding universe starting from a dense singularity

  • Currently accepted model of the universe's formation

Monsignor Georges Lemaitre

• Catholic priest, physicist, and astronomer

• Proposed the theory of an expanding universe and the "hypothesis of the primeval atom"

• Pioneer in applying Einstein's theory of relativity in cosmology

• Studied civil engineering and astronomy, received a PhD in physics

• Born in Belgium in 1894, died in 1966 at the age of 71

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• Astronomers use physics and mathematics to study the universe

  • They work in fields such as education, research, data analysis, and software development

• The universe may have started with the Big Bang around 13.8 billion years ago

• Galaxies began forming about one billion years after the Big Bang

• The Solar System and Earth are approximately 4.54 billion years old

• Models of the universe:

  • Geocentric Universe: Aristotle and Ptolemy believed Earth was motionless and everything revolved around it

  • Heliocentric Universe: Copernicus demonstrated that celestial objects can be explained without Earth at the center

    • Giordano Bruno suggested that the Solar System is not in the center of the universe, but just one among many

• Nebular theory proposed by Kant Laplace suggests the Solar System started as a large cloud of gas that contracted due to self-gravity

  • However, it couldn't explain the distribution of mass and angular momentum in the Solar System

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• Angular Momentum is the quantity of rotation of a body

• Nebula is a cloud of dispersed interstellar gas, hot gas, and dust

• Planetesimal Hypotheses proposed by Chamberlin-Moulton

• Tidal Theory proposed by Jeans-Jeffreys

• Protoplanet Theory proposed by Kuiper & Weizsacker and supported by Harold Urey

  • It is a modified version of the Nebular Hypothesis

  • Based on swirling gas and dust, leading to the formation of planets and stars

• The Solar System began with a fragment from an interstellar cloud composed mainly of hydrogen, helium, and trace amounts of light elements

• Planetesimals are larger asteroid-sized aggregates that oriented the center of the solar nebula

• Terrestrial planets formed near the central portion of the solar nebula, while gas giants formed in the outer disk

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• Encounter Hypothesis suggests that a rogue star passed close to the sun about 5 billion years ago

• The encounter stripped materials from both the sun and the rogue star, which coalesced into smaller lumps and formed the planets

• The encounter hypothesis explains why all the planets revolve in the same direction and why the inner planets are denser than the outer ones