Journey through nearly 14 billion years of history with the Big History Project, now available on Khan Academy. This course asks the big questions about our Universe, our planet, life and humanity. Examine our shared history across scales and disciplines. From the Big Bang to our still expanding universe, this course, created and maintained by the Big History Project, will lead you on a journey of astounding connections and exciting discoveries.
About Image Community Questions

1. What Is Big History?

Where did everything come from? How did we get to where we are now? Where do humans fit in? Where are things heading? These are questions that origin stories of different cultures have addressed for thousands of years. Big History attempts to answer them by examining the entire past of the Universe using the best available ideas from disciplines such as astronomy, chemistry, biology, and history. Throughout the course, you’ll explore different scales of time and space and view human history from new angles. You’ll learn what we know and what we don’t, consider our place in the Universe, and develop your own ideas for what the future may hold.

2. The Big Bang

Big History will introduce you to many new ideas and claims. You won’t simply accept these claims as facts and move on. You’ll be encouraged to test them. You’ll learn how to evaluate information presented to you, and be encouraged to decide for yourself what to believe and what to investigate further. This is how our thinking advances. Today’s scientific view of the history of the Universe is based on the work of thousands of scientists and scholars over thousands of years. People built upon each other’s work. New technology and new observations have led to ever sharper theories about the Universe and its beginnings. As you study how these views have evolved, you’ll develop your own skills for testing the claims of others and making claims of your own.

3. Stars & Elements

By 200 million years after the Big Bang, the Universe had become a very dark and cold place. Then things started to change. First, galaxies and nebulae formed. These were the earliest structures in the Universe. Then stars – “hot spots” of light and energy – emerged from these clouds of dust and gas. Why did they form and how did they change everything? Stars, the first complex, stable entities in the Universe, have the capacity to generate energy for millions, even billions of years. The first stars, which passed through their entire life cycles relatively quickly, produced many of the chemical elements of the periodic table. In this unit, you’ll learn how stars first formed and how the lives and deaths of stars provided the chemical diversity necessary for even more complex things.

4. Our Solar System & Earth

Billowing clouds of matter spun around and around our young Sun, gradually forming just about everything in our Solar System – from meteors and asteroids to all the planets and moons. One planet in particular would enable the creation of even more remarkable complexity.

5. Life

What makes life so special? Is there life elsewhere in the Universe? And how exactly did life emerge and diversify? In many ways these remain mysteries, but we do have enough evidence to explore some possible answers.

6. Early Humans

Humans are unusual. We walk upright and build cities, we travel from continent to continent in hours, and we communicate across the globe in an instant. We alone can build bombs and invent medicines. Why can we do all these things that other creatures can’t? What makes us so different from other species?

7. Agriculture & Civilization

If everyone had to survive as foragers, there wouldn't be nearly enough food to feed 7 billion people. Farming sustains us, and it's easy to assume it has always existed, but it hasn't. Humans invented agriculture. This altered our relationship with the Earth, drove population growth, and enabled the emergence of magnificent civilizations.

8. Expansion & Interconnection

Early humans had pretty small social networks. At most, they probably met only a couple hundred people who probably all lived very similar lives to their own. As people started farming, these networks got larger. People were increasingly specialized in their work and trade. Populations in cities got larger. Trade reached across longer distances, bringing together people with very different lives and ways of thinking.

9. Acceleration

Just 500 years ago, humans lived in four separate world zones, each with distinct cultures and technologies. Now, humanity is linked within one interconnected network of information and commerce that spans the entire planet.

10. The Future

What does 13.8 billion years of history tell you about yourself? How does knowing so much about the past change the way you think about the future? These may be the most important questions Big History asks. How would you answer them? Big History is an unfinished story.