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All 16 learnings · one per slide
Cosmos
Carl Sagan, in bytes
16 key learnings on the universe, science and our place in it.
16 learnings · ~40 sec eachSwipe →
Library / Big Ideas & History / Cosmos
Cosmos, in bytes
16 key learnings from Carl Sagan's companion to his TV series, exploring the cosmos and the history of science. Each takes about 40 seconds to read. Swipe, use the arrows, or your keyboard.
Books in Bytes
Learning 1 · Chapter 1
The Shores of the Cosmic Ocean
The idea
Sagan describes the universe as a vast ocean, with Earth a tiny speck on its shore.
Example
Billions of galaxies, each with billions of stars.
Takeaway
We are small, and that's awe-inspiring.
Cosmosbooksinbytes.in
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Learning 2 · Chapter 1
Eratosthenes Measures the Earth
The story
In ancient Egypt, Eratosthenes compared shadows in two cities to calculate the Earth's circumference.
The result
He was remarkably close.
Takeaway
Simple observation plus reasoning can reveal big truths.
Cosmosbooksinbytes.in
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Learning 3 · Chapter 2
The Heike Crab
The story
In Japan, crabs whose shells resemble samurai faces were thrown back by fishermen, so they became more common.
The lesson
An example Sagan uses for artificial selection.
Takeaway
Selection shapes life.
Cosmosbooksinbytes.in
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Learning 4 · Chapter 9
We Are Star Stuff
The idea
The elements in our bodies were forged inside stars.
Example
Carbon, oxygen and iron came from stellar furnaces.
Takeaway
We are connected to the cosmos.
Cosmosbooksinbytes.in
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Learning 5 · Chapter 3
Kepler and Tycho
The story
Johannes Kepler used Tycho Brahe's precise observations to find that planets move in ellipses.
The lesson
Kepler abandoned beautiful theories when data disagreed.
Takeaway
Follow the evidence.
Cosmosbooksinbytes.in
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Learning 6 · Chapter 4
Venus: A Warning
The idea
Venus has a runaway greenhouse effect, making its surface hot enough to melt lead.
The lesson
It's a warning about changing Earth's atmosphere.
Takeaway
Planets teach us about Earth.
Cosmosbooksinbytes.in
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Learning 7 · Chapter 5
Mars and the Search for Life
The story
The Viking landers searched Mars for life in the 1970s.
The result
They found no clear evidence, but questions remain.
Takeaway
Searching is how we learn.
Cosmosbooksinbytes.in
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Learning 8 · Chapter 6
Voyager's Journey
The story
Voyager spacecraft revealed Jupiter, Saturn and their moons in detail.
Example
Volcanoes on Jupiter's moon Io.
Takeaway
Exploration surprises us.
Cosmosbooksinbytes.in
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Learning 9 · Chapter 7
The Ionian Awakening
The idea
Ancient Ionian Greeks began explaining the world through natural causes, not gods.
Example
Democritus proposed atoms.
Takeaway
Science began with questions.
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Learning 10 · Chapter 8
Travels in Space and Time
The idea
Relativity shows time slows near the speed of light.
Example
A space traveller would age more slowly.
Takeaway
The universe is strange.
Cosmosbooksinbytes.in
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Learning 11 · Chapter 9
The Lives of Stars
The idea
Stars are born, live and die, some exploding as supernovae.
Example
Supernovae spread elements into space.
Takeaway
Death creates new life.
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Learning 12 · Chapter 10
The Edge of Forever
The idea
The universe began with the Big Bang and has been expanding ever since; it may expand forever or one day contract.
Example
Sagan notes Hindu cosmology imagines time scales of billions of years, like modern science.
Takeaway
Deep time is humbling.
Cosmosbooksinbytes.in
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Learning 13 · Chapter 12
The Drake Equation
The idea
Frank Drake's equation estimates the number of civilisations we might contact.
Example
Multiplying factors like the number of stars and planets.
Takeaway
We might not be alone.
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Learning 14 · Chapter 13
The Library of Alexandria
The story
The ancient library held much of the world's knowledge, until it was destroyed.
Example
The scholar Hypatia was killed by a mob.
Takeaway
Knowledge can be lost.
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Learning 15 · Chapter 13
Who Speaks for Earth?
The idea
Sagan warns that nuclear weapons could destroy civilisation.
Example
The arms race of the Cold War.
Takeaway
We must protect our home.
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Learning 16 · Chapter 13
Wonder and Scepticism
The idea
Sagan urges balancing open-minded wonder with careful scepticism.
Example
Testing extraordinary claims.
Reflect
What would you like to understand about the universe?
Cosmosbooksinbytes.in
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All 16 learnings complete
That’s all 16 learnings.
We are a way for the cosmos to know itself. What would you like to understand about the universe?
Abhay Kumar JaiswalFCA · PMP® · Workday Financeabhayjaiswal.com
Summaries in my own words. Read the book for the full stories.
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Summaries are written in my own words for learning. Read Cosmos by Carl Sagan (1980) for the full stories. More Books in Bytes