Cosmology and the Universe
Cosmology is the scientific study of the origin, evolution, and structure of the universe, from the Big Bang to the present-day cosmos including dark matter and dark energy.
What You Need to Know
Key Concept Diagram
The Big Bang theory describes the universe beginning from an extremely hot, dense state approximately 13.8 billion years ago
The universe is expanding — distant galaxies are moving away from us (Hubble's law)
Cosmic Microwave Background radiation is evidence for the Big Bang
Dark matter and dark energy make up about 95% of the total mass-energy of the universe
The observable universe is approximately 93 billion light-years in diameter
Key Vocabulary
Big Bang
The cosmological model describing the origin of the universe from an initial extremely hot, dense state
Hubble's law
The observation that galaxies recede from us at speeds proportional to their distance
Dark matter
Invisible matter that does not interact with light but has gravitational effects
Cosmic Microwave Background
Low-level radiation permeating the universe, considered a remnant of the Big Bang
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
The redshift of light from distant galaxies provides evidence for:
Question 2
The Cosmic Microwave Background radiation is important because:
Question 3
Approximately what percentage of the universe is made up of dark matter and dark energy?
Key Concepts Summary
- ●The Big Bang theory describes the universe beginning from an extremely hot, dense state approximately 13.8 billion years ago
- ●The universe is expanding — distant galaxies are moving away from us (Hubble's law)
- ●Cosmic Microwave Background radiation is evidence for the Big Bang
- ●Dark matter and dark energy make up about 95% of the total mass-energy of the universe
- ●The observable universe is approximately 93 billion light-years in diameter