Big History tells the story of our Universe. It asks big questions about where we came from, and it uses scientific and historical evidence to answer them. This evidence has been gathered by many generations of thinkers. Our evidence and our understanding constantly change as new thinkers share new information. Let’s look at how humans build and share knowledge.

People are curious. We want to understand the world we live in. Humans have always shared stories about the world around them and how it works. These stories helped people improve their lives and teach their children. Our ancestors gradually learned how to study the Earth, watch the stars, and experiment to test their ideas. This gave us evidence to build more-complex and interconnected ideas. Eventually, we grouped these connected sets of ideas together as disciplines (fields of study) like physics, biology, and history. This process of telling stories and using evidence to back up claims is how we began to create a shared collection of “what we know,” which we call knowledge.

In the modern world, we humans record and store our knowledge in books, libraries, and the Internet. These records help us share ideas and build upon what we know. Our knowledge is constantly improving as we learn more about ourselves and the world we live in. We refer to humans’ ability to share, store, and improve knowledge over time as collective learning.

Hypothesis: a proposed explanation that accounts for observed phenomena or known facts and that can be used to guide further investigation

Astronomer: a scientist who studies the universe beyond the Earth

"IN 1609, GALILEO BECAME THE FIRST PERSON TO USE A TELESCOPE TO STUDY THE NIGHT SKY."

But just because knowledge is recorded and shared doesn’t necessarily mean that it’s true—especially today. In our modern world, we have access to so much information, it can be difficult to know what’s true and what’s fake. But humans have been fact-checking each other for thousands of years.

Creating new knowledge

How do people create knowledge? Most scholars begin with a question. Using what they’ve learned or read, they make a thoughtful guess to answer their question. These thoughtful guesses are called hypotheses. The next step scholars take is deciding what information they need to support their hypothesis. Usually, they begin collecting information by reading or listening to what other experts have said on the topic. Sometimes, people need to create new tools—like a new microscope or telescope—to help them gather information and make observations. Many spend years observing and taking notes on what they see and read. Sometimes, this process results in scholars creating entirely new ways of thinking.

Let’s look at one example—an astronomer named Galileo Galilei, who lived in Italy 400 years ago. Before Galileo, most people believed that the Sun and planets orbited around the Earth. But in the early 1600s, Galileo Galilei asked a question that challenged that belief: Does the Sun revolve around the Earth, or does the Earth revolve around the Sun? Let’s explore how knowledge gets created by learning a little about what Galileo did next.

Galileo had read the work of Copernicus, an astronomer who lived a century earlier. Copernicus had used calculations to support the claim that the Earth revolves around the Sun. But Copernicus didn’t have the right tools to confirm his calculations. By the time Galileo was asking questions, a hundred years later, the telescope had been invented, and Galileo himself had improved its design. In 1609, he became the first person to use a telescope to look up at the night sky. Galileo spent a lot of time observing how the planets moved. He noticed that Venus moved through the sky in a way that would not be possible if that planet orbited the Earth. He also discovered there were four moons orbiting Jupiter. This evidence showed him that not all bodies in our Solar System orbit the Earth, and that Copernicus’s calculations had to be correct.

After scholars collect, organize, read, and talk about the evidence and information with others who work on the same topics, they next see if they can make a claim to answer their questions. They use the evidence they gathered to support their claims. After Galileo gathered all his observations and evidence, he answered his question and made his claim that the Earth—and the rest of the Solar System—revolved around the Sun.

Sharing new knowledge

Once a scholar is sure about their claim, they share it with other experts. The scholar explains why the question is important and shows how the evidence they collected confirms their claim. The other scholars consider this new claim and compare it with what they already know, and they then decide whether they think the claim is valid. This process is called peer review, and it helps scholars get support to publish their research—in a book, a journal, or online.

Throughout history, there have been many authorities and scholars who refuse to believe new ideas and who reject new ways of thinking. For Galileo, this rejection came from the Catholic Church, which challenged his ideas because they went against church teachings. Galileo was put on trial and spent the rest of his life under house arrest, although he continued to make observations, gather evidence, and write about the results.

Different approaches to knowledge

All scholars, from archaeologists to zoologists, begin by asking important questions. They all make hypotheses, gather data, and analyze that information to make claims. But there are also important differences in their processes for creating knowledge. Experts in different fields might ask very different questions, have different rules about what evidence is valid, and have different ways of gathering data.

In this course, we’re studying the history of the entire Universe. So, we need to understand how scholars from many different fields ask questions, gather data, and make claims. As you learn about different scholars throughout history and in the present, think about how they do their work. What questions do they ask? How do they answer them? Do you agree with their conclusions?

Lots of questions will come up for you in this course. You might even encounter a few claims that you don’t believe, or evidence you don’t trust. You can ask questions, make hypotheses, and challenge claims. Just be sure to follow the steps for gathering the evidence you need to prove your claims.