The Big Bang Theory
How everything began, from a singularity to galaxies in 13.8 billion years
In the beginning...
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Lessons
Not an explosion
Practice: Myth or fact
Stretched light
Practice: Line up the lines
Hubble's law
Practice: Use Hubble's law
How old is the universe?
Practice: Rewind the clock
Cosmic inflation
Practice: What inflation explains
The first minutes
Practice: Count the helium
The first light
The cosmic microwave background
Practice: Stretch the glow
Dark ages and the first stars
Practice: Order the story
Dark matter
Dark energy
Practice: The cosmic budget
The evidence
Practice: Sort the evidence
What we still don't know
Course Complete
Up nextRecommended first Launch Lesson
An expanding universe
Trace the history of the universe from the first fraction of a second to the present day. Explore cosmic inflation, nucleosynthesis, the CMB, dark matter, and dark energy.
