WATCH: Unit 1 Overview - What Is Big History?

Where do we come from? Where are we going? Who are we? If you ever looked up into the sky at night and asked yourself any of these questions, you're not alone. I don't have all the answers, unless your question is "Who is that?" which I totally know. I'm Rachel Hansen. And while I can't predict the future, I do know that  you'll be seeing me nine more times this year in each unit overview to learn about something we  call Big History.   Ever since we developed language, humans have been telling each other stories about  the origins of the world and our place in it. These origin stories all try to do something  similar, they seek to tell the listener that   there's some sense to it all, that the universe has  structure, and that we fit into it.   Different people tell many different stories about the past. In the Big History Project we call them narratives. Depending upon what your evidence tells  you and which elements you highlight   your narrative will change. There's no single story  about past events that can tell us everything.   For example, think about the last time you had  an argument with a friend. Afterward, did you both agree about who was right and who was wrong? Did you both remember your fight the exact same way? Did you both bring up the same evidence  to show that you were right?   I'm guessing probably not. I'm guessing you both had two  very different narratives about that past event. That's a small example, but in Big History we have  a really big narrative about the universe and our place in it. It starts 13.8 billion years ago with  the big bang and continues into the distant future. To support this narrative we'll be using a lot of  historical evidence but our narrative starts long before humans even existed. So we'll often look to science for our evidence. Our course is divided into 10 units you'll see me in an introductory  video like this at the beginning of each unit. But the narrative of this course is also marked  by eight thresholds of increasing complexity, or just thresholds. I know! Ten units?! Eight  thresholds?! What?!    But just think of it this way: the ten units are like chapters in a book. They divide the big history story into blocks of time that will help us organize things. The eight thresholds, on the other hand, are crucial turning points in the big history narrative  when something really big changed. Something like the sun was born or living things exist now. Some units have multiple thresholds and some have none  As we move through the 10 units of this  course we'll explore these eight thresholds   of increasing complexity as we try to  understand how we got to where we are. [instrumental music] Oh! It's time for questions from the audience! Which is weird, because this is pre-recorded. [laugh track] The first question is What's all this science doing in my  history class?  And this one says Why do i have to learn history to understand astrophysics?  Two very good questions from two very inquisitive students. Well, in these ten overview videos i'm going to  help you answer both of those questions.   As we move through the course, I'll help you understand how  we know what we know.  And we'll also investigate how people living in many periods have  changed and deepened their understanding of the universe and everything in it. That's the history part. And  yes, okay, for a history class it might seem like a lot of science talk, but it's still history! Science might seem like an unchanging story. Stuff like, the law of gravity sound pretty darn permanent,  and historians can't change how gravity works. [Marker thuds on floor] Every time. But, our understanding of gravity  can change because we're humans.   We've got these squishy little brains filled with funny ideas  and nagging questions.   How humans understand and explain the world around us changes all the time.   And it's changed a ton in the last few thousand years. Reshaping how we interact with our world  and the stories we tell about our place in it. That's why history and science go together  like peanut butter and jelly or like flannel and Fridays. We think you'll understand humanity's  place in this universe better if you learn how we fit in with all the supernovae black holes, quarks,  and chemical compounds that make it up.   but we also think you'll understand all those sciency bits  a little better if you understand the history of human thought.  From how our ancestors explain the  origins of their world to  the scientists using a telescope the size of a school bus to peer back in time at the explosive origins of our universe. [instrumental music] In Unit 1 you're going to  learn about some big stuff. But you're also going to encounter some teeny tiny  stuff like atoms and molecules.  So, you'll need to  learn how to zoom out to identify big patterns  and zoom back in to comprehend smaller changes. That's called scale switching, and it's an  important tool in your historian toolbox.  Next, you'll dive into some narratives that  people in the past have used to explain the   existence of life, the universe, and everything.   You'll compare these ancient origin stories with  the modern scientific origin story offered  by Big History.   Finally, you'll meet historian Bob Bain, who will introduce you to one of  the most important tools of a historian: claim testing. How do we know what we know? And  how do we choose which narratives to believe? You'll learn how to use intuition, logic, authority, and evidence to evaluate claims made by others. Understanding chemistry, astrophysics, forensics, archaeology, and a bunch   of other schools of thought will give you  more evidence to examine historical claims. That's another reason we've put all this science in your history class. Some historians think of history only in  terms of recorded history, meaning that it   started only five thousand years ago when we  started writing things down.   But look at this. This paper clip represents five thousand years.  That's all recorded history. All the clay tablets, Egyptian hieroglyphics, Greek plays, Chinese  philosophy, all the religious texts ever   written, all your favorite novels, all the social  media posts. It all fits in these 5,000 years. In this one inch. Get ready for some scale switching. I would need 50 paper clips to get to 250,000 years, which is how long our species has been on the planet. To represent the 4.56 billion years our planet has existed, I'd need over 14 miles of paper clips. That's longer than the island of manhattan! And to reach 13.8 billion years, the age of our universe, my paper clip chain would stretch 43.5 miles, stretching across the state of  Delaware and into the Atlantic ocean. That's an awful lot of time that recorded  history leaves out.   If we only pay attention to what's been written down we lose a lot  of the rich diversity of human experience. We also miss the connections between our universe, solar system, planet, and us. comprehending the origins of the universe requires the tools  of chemistry and physics and a bunch of other disciplines. But we'll also need the tools of  the historian like scale switching and claim testing if we're going to understand how  we know what we know and why that matters. Okay that's 1,000 paper clips just 2 million  759,000 more to go to get to 43 and a half miles. It's gonna be a long night. Hey! I'm clipping here! What?! We can do the paper clip thing with CGI?!   Well, that would have been nice to  know about 999 paperclips ago. Wish I had a time machine.