Origin and Composition of the Universe and Solar System

Flashcards covering the components and age of the universe, scientific and non-scientific origins of the universe, and theories regarding the formation of the solar system.

Universe

The totality of everything that exists.

Baryonic Matter

A component of the universe making up $5\%$ of its composition, including the matter that makes up humans.

Dark Matter

A component of the universe representing $27\%$ of its total composition.

Dark Energy

A component of the universe representing $68\%$ of its total composition.

Age of the Universe

The universe is approximately $13.8$ billion years old.

HD 140 283

Commonly known as the "Methuselah" star, it is the oldest star identified in the notes.

Big Bang Theory

A physical theory proposed by Georges Lemaitre (1920) and Edwin Hubble describing how the universe expanded from an initial state of high density and temperature.

Cosmic Microwave Background

The oldest light in the universe, associated with the recombination stage of the Big Bang Theory.

Big Crunch Theory

Proposed by Alexander Friedmann (1922), this theory states the universe will one day stop expanding and contract back into a super dense singularity.

Oscillating Theory

Proposed by Richard Tolman in the 1930s, this theory combines the Big Bang and Big Crunch as a cyclical event.

Steady State Theory

Proposed by Fred Hoyle, Hermann Bondi, and Thomas Gold (1948), it suggests the universe is always expanding but maintains a constant average density and is the same at all times and directions.

Solar System

The gravitationally bound system consisting of the sun and everything that orbits it.

Planetesimal Theory

A theory by Forrest Moulton and Thomas Chamberlin (1905) suggesting planets formed from small bits of matter (planetesimals) originating from gases pulled out by a near collision with a passing star.

Tidal Theory

Proposed by Sir James Jeans and Sir Harold Jeffreys (1918), it suggests tidal forces from an approaching star caused part of the Sun's mass to be torn off to form planets.

Nebular Theory (Solar Nebular Disk Model)

A theory by Immanuel Kant (1755), Pierre Laplace (1796), and Emanuel Swedenborg (1734) stating a spinning nebula flattened into a protoplanetary disk to form a solar system.

Gravitational Collapse

Stage 1 of the Nebular Theory.

Spinning and Flattening

Stage 2 of the Nebular Theory.

Accretion and Planetesimal Formation

Stage 3 of the Nebular Theory.

System Stabilization and Clearing

Stage 4 of the Nebular Theory.

Voyager 1

A space probe that has been active from 1977 to the present.