LESSON 1.1 : Theories on the Origin of the Universe

Genesis

Hebrew Bible and Christian Old Testament: God created everything in six days; light was separated from darkness first.

Brahmanda

Hindu text Rigveda: “Cosmic Egg” that expands from a point called “Bindu” and eventually collapses.

Primordial Uiverse

Anaxagoras: mixture set in motion by “nous” (mind) to sift ingredients

Atomic Universe

Leucippus and Democritus: universe is made of indivisible, eternal atoms in an infinite void

Geocentric Universe

Aristotle and Ptolemy: Earth is motionless at the center

Heliocentric Universe

Nicolaus Copernicus (1543): Celestial objects don’t revolve around Earth

Static/Infinite Model

Sir Isaac Newton (1687): Matter is uniformly distributed and gravitationally balanced but unstable

Cartesian Vortex

Rene Descartes: Space is filled with matter swirling in large and small vortices

Big Bang Theory

Georges Lemaitre (1927): Universe originates from an infinitely dense singularity ~14 Ga

Steady State Theory

Hoyle, Gold, Bondi: Universe expands but density remains constant by inserting new matter

Inflationary Model

Alan Guth: Incorporates a short period of exponential cosmic inflation to solve the horizon/flatness problem

Multiverse

Developed by Andrei Linde (1983) and Hugh Everett III/Bryan De Witt: Universe is one of many “bubbles”

Fraction of a Second

Four forces formed: Gravity, Electromagnetic, Strong Nuclear, and Weak Nuclear

3 Minutes

Protons and neutrons fuse to form nuclei of Hydrogen and Helium

300,000 years

Temperatures cool for atoms to fully form; photons escape and light exists for the first time

300 million years

Stars and galaxies form; composition shifts from light elements to heavier elements via supernova

redshift

shift of light toward the red end of the spectrum, occurs when a light source is moving away from the observer

Doppler effect

explains changes in wave frequency due to motion

• moving away → longer wavelength → redshift

• moving closer → shorter wavelength → blueshift

Cosmic Microwave Background

left over heat from the early universe