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Big History: An Overview
Big History: An Overview
By John Green, adapted by Newsela
History is an attempt to understand both our
insignificance and our significance. To study history is
to better understand the world and your place in it.
You are very small. You are one of several billion living members of your species, a
species that lives on the fifth largest planet orbiting a star we call the Sun. There are
more than a hundred billion such stars in our galaxy, and perhaps a hundred billion
galaxies in the Universe. It’s almost impossible to grasp your smallness—there are
more stars in the Universe than there are grains of sand on Earth.
And yet, you’re also very large. You’re a member of an extraordinarily powerful
species that has dramatically reshaped the biosphere, the first species on Earth to
understand the vastness of the Universe around it. Your choices—how to organize
your community, what to value, what to battle against—shape not just your life but the
lives of those around you and the lives of those still to come. And you are physically
vast as well: Your body contains trillions of cells, and is colonized by trillions more
microscopic organisms.
What Is History?
History is an attempt to understand both our insignificance and our significance. To
study history is to better understand the world and your place in it. You, and the other
humans with whom you share this world, are the culmination of the human story.
What Is Big History?
There’s a lot more to history than the human story. Let’s consider the world before
humans. If you think of history as the story of life on Earth, almost all of it played out
before our species (Homo sapiens) showed up on the scene. After all, we’ve been around
only for the last 250,000 or so years—less than 0.01% of the history of life on Earth.
From the very beginning, we’ve had different stories that explain the origins of the
Universe, our planet Earth, and life itself. These origin stories, as they’re called, are as
varied as the cultures that created them. At its heart, Big History is simply another
origin story. However, it differs from all other origin stories because it’s science based. Big History uses the information we have available—the scientific evidence—to
create an understanding of the Universe.
Because the scale of Big History is so vast (remember, it covers the history of the
Universe), it would be impossible for this story to include everything. All historians have
to make choices about what to include and what to leave out in the stories they tell. So,
what does the story of Big History focus on? Big Historians focus on eight turning
points in the history of the Universe, which we call thresholds. These are moments when
the Universe became significantly more complex than it had been previously
Threshold 1: The Big Bang
Modern science suggests that the Universe was created in a “big bang” about 13.8
billion years ago.
The Big Bang was a split second in which all matter and energy expanded at tremendous
speed and became the Universe. What was there before the Big Bang? It’s mind-bending
to think about, but in some ways, there was no “before” the Big Bang, because the Big
Bang created not only space as we know it, but also time as we know it. The important
thing to know is that around 13.8 billion years ago, very suddenly, the Universe exploded
into being. It’s also important to recognize that although scientists know a lot about the
Big Bang, there are still many questions about the details that are being researched.
Threshold 2: The Stars Light Up
After the Big Bang, the Universe expanded and cooled. It took some time (about
380,000 years), but eventually it was cool enough for the simplest atoms, hydrogen
and helium, to form. The early Universe consisted almost entirely of hydrogen and
helium for a very long time. After a few hundred million years, clouds of hydrogen and
helium began to collapse, and the increasing heat and pressure generated by collapse
led to the creation of the first stars. Stars represent the second threshold of increasing
complexity in Big History. Not only are stars more complex than simple atoms, they’re
also able to create tremendous energy. Over time, gravity grouped stars into galaxies,
which created further complexity in the Universe.
Threshold 3: New Chemical Elements
Stars made the Universe more complex, but the Universe still consisted primarily of
hydrogen and helium. This changed when the first generation of stars died. The death
of a star can generate high temperatures and pressures like those in the Big Bang, and
this makes possible the creation of more complex atoms. A greater variety of atoms is
critical to making more complex things like planets and living things, so the death of
stars is the third threshold of increasing complexity in Big History.
Threshold 4: Earth and the Solar System
Our Sun is a star, and like all other stars, it was formed from the collapse of a huge
cloud of gas and dust particles. More than 99 percent of this material went to make up
the Sun, but wisps of matter orbited around it at various distances. Over time, the matter
in each orbit was drawn together by gravity. The gravitational pull created violent
collisions into lumps of matter that eventually formed the planets. This process, which
we call accretion, is how our Earth was formed approximately 4.5 billion years ago.
Threshold 5: Life
Around volcanic vents at the bottom of Earth’s oceans, complex chemicals engaged in
ever-changing reactions powered by the heat from these volcanoes. Those reactions
led to the formation of complex chemicals that eventually created the first living
organisms. The earliest living organisms consisted of single cells, as most living
organisms do even today. Like all living organisms, those early single-celled creatures
were subject to the laws of evolution. Generation by generation, the average features
of species gradually changed, eventually forming entirely new species.
And for a very long time, that was it: single-celled, microscopic organisms. Life first
emerged on Earth perhaps three billion years ago; the first multicellular life didn’t show
up until around one billion years ago. But slowly, life grew more and more complex, and
large, multi-cellular organisms eventually spread, not only in water, but also on land.
One hundred million years ago, the land-based animals that flourished most were the
reptiles we call dinosaurs. About 65 million years ago, however, most of them died off.
Now other types of large animals could flourish in their place. Most successful of all in
the last 65 million years has been the large class of animals called mammals.
Threshold 6: Collective Learning
The extinction of the dinosaurs allowed mammals and primates to evolve and
eventually dominate the Earth.
Our ancestors, the hominins, are primates, and they first appeared between five and
seven million years ago in Africa. Over millions of years, hominins evolved in
important ways, both physically and socially. About 200,000 years ago, Homo sapiens,
which means “wise human,” appeared. Modern humans developed language, a method
of communication that allows them to share complex ideas and pass on knowledge
from generation to generation. This process is known as collective learning. In other
species, knowledge dies with the generation that created it. Humans have the ability to
build on the accomplishments of previous generations.
Threshold 7: Agriculture
Our ancestors lived by foraging. Foragers survive by gathering plants, hunting animals,
and scavenging the remains of animals killed by other predators. Foraging supported
early humans for millions of years. About 12,000 years ago, humans began to
domesticate plants and animals, in other words, to farm. They began interfering with
the natural life cycles of plants and animals in order to control where they grew and
promote characteristics in those plants and animals they preferred. Growing food gave humans access to a vast amount of energy created by the Sun through photosynthesis.
Because foraging for survival was no longer necessary, tremendous lifestyle changes
were possible, like settling down to live in cities, creating political structures, and
developing skill and trade specializations. The results of all of these changes define
the agrarian civilizations. Farming has had a tremendous impact on the way humans
live and how they interact with the Earth.
Threshold 8: Modern Revolution
The adoption of farming led to dramatic changes in the way humans lived. Innovation
accelerated dramatically with the Modern Revolution, which began about 300 years
ago. Rapid growth of human population and the creation of a highly interconnected
world are some of the key features of the modern world. These features make the
modern world the eighth and final of Big History’s thresholds.
What's Next?
The story of the Universe isn’t only about the past. We know that this story doesn’t end
with Threshold 8. So, what’s next? What might the next threshold of increasing
complexity be? When you reach the end of this course, you’ll get to use your
knowledge of the past to speculate about the future. Because Big History isn’t just
about knowing what happened when. Big Historians look across the thresholds to
understand the connections between past and present. With that understanding,
developing a view of what the future might hold becomes more than a random
guessing game. It becomes a way of expressing your own point of view about how the
future will be the logical outcome of billions of years of the past.
But let’s not get ahead of ourselves. Let’s really dig into the vastness of what got us
here. Remember, you are very small, yet very large. In any other story, this might
seem like a contradiction—but not here, not in the Big History story!
Want to join the conversation?
- “Not only are stars more complex than simple atoms, they’re also able to create tremendous energy. Over time, gravity grouped stars into galaxies, which created further complexity in the Universe.”
Doesn’t it contradict the first law of thermodynamics to say that stars create energy? And gravity grouped stars into galaxies? Gravity? Doesn’t gravity just happen on planets? And what about dark matter then?
“In other species, knowledge dies with the generation that created it. Humans have the ability to build on the accomplishments of previous generations.”
Knowledge is passed on from one generation onto the other no matter the species. Unless the entire group is wiped out all at once then yes knowledge won’t get passed on.(3 votes)- No, it doesn't violate the 1st law because they are converting mass into energy via fusion.
Gravity is a property of all mass. The more massive an object, the more gravity it exerts.
Not all knowledge is passed from generation to generation. Many species don't pass any knowledge, let alone do they even have a nervous systems capable of building or containing knowledge. Plants and bacteria are two large sets that don't contain knowledge.(3 votes)
- might artificial intelligence be a threshold?
I mean maybe in the future, artificial intelligence was be going to be improved enough to help us answer some questions we can't answer or understand without its help. I don't mention AI which destroys humanity or takes control
(I hope you get the point what I exactly mean)(1 vote)