Chapter 1
The cosmic horizon of our sight
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Chapter 2
The shape and geometry of space
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Chapter 3
Is there an edge to everything
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Chapter 4
The expanding cosmos and cosmic speed limits
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Chapter 5
Three ultimate fates of the universe
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YOUR GOAL
Master of Is the universe infinite
Ch 1 · The cosmic horizon of our sight
artiteacher The Cosmic Horizon
Space is stretching out / billions of light-years wide / we're looking back in time!
Fun Fact
Cosmic time travel: Light from the Sun takes 8 minutes and 20 seconds to reach Earth, meaning we always see the Sun in the past.
Glossary
cosmic horizon (noun)
The theoretical boundary marking the maximum distance from which light can reach an observer. Our current limit of visibility spans a diameter of roughly 93 billion light-years.
The theoretical boundary marking the maximum distance from which light can reach an observer. Our current limit of visibility spans a diameter of roughly 93 billion light-years.
Quiz
What is the name of the oldest light in the universe, dating back to 380,000 years after the Big Bang?
Quiz
Which cosmic speed limit prevents us from seeing the entire universe instantly?
Quiz
Which ancient Chinese philosopher wrote about the concept of infinite space around 400 BCE?
