Big History Project
by: lemuer esquillin
Where did everything come from? Where are we heading? Big History tells the story of the Universe starting from the Big Bang, the formation of stars, planets, life on Earth, modern civilization and what might exist in the future.
In the Beginning
To grasp the entirety of the Universe we divide Big History into eight "thresholds." You may consider a threshold a transition point. It's an event that creates something completely new.
Every culture has its own origin story. They may be very short anecdotes. Or they might be elaborate narratives that help explain the mysteries of our existence.
THE BIG BANG
What is known is that, within a few millionths of a second, the Universe expanded at an inconceivable speed. From that expansion, some recognizable subatomic particles and fundamental forces formed. Then the Universe cooled dramatically — to about 1 billion degrees Celsius, allowing energy, and then matter, to appear. Much later, after dropping to a cool 1,650 degrees, the first hydrogen and helium atoms formed.
Whether stargazing distant galaxies with the naked eye, viewing protons under powerful magnification, or listening to the beginning of time and space, thinking about how different things appear from different viewpoints is key to understanding Big History.
Gravity squeezes the center of the protostars tighter and tighter. Their temperature rockets until they reach a flash point. And they "light up" as free-floating nuclei, slamming together with such intensity that they fuse into a new element. This process of "nuclear fusion" releases a tremendous amount of energy, presenting the Universe with a new complexity that is critical to the formation of galaxies, larger clusters, and superclusters.
Three centuries after Isaac Newton watched an apple fall from a tree to the earth, we are still trying to completely comprehend the nature of gravity.Also, the larger and denser an object is, the stronger the gravitational pull it exerts on another object. The massive Earth pulls your smaller body mass to it. This gravitational pull prevents you from floating off into space. At the same time, the mass of your body, as Newton described, is actually exerting a tiny gravitational pull on Earth.
THE BIRTH OF MATTER AND ELEMENTS
The Universe is so big, we don't actually know how big it is. But we do know it's beige. John and Hank Green explain the huge scale of the Universe, why chemistry is so important to understanding Big History, and how we're all made of stars.
COMPLEXITY EXPLODES INTO THE UNIVERSE
A catastrophic event begins. Lacking the outpouring of energy from its core, the star collapses. Its many outer layers fall inwards, in an enormous unbelievable avalanche of matter crumbling due to the pull of gravity from the dense core. They slam with unimaginable force into the star's iron center, creating new elements. These new elements bounce off the iron core, hurtling outwards into space.
THE PERIODIC TABLE
Aristotle believed the Earth resided at the center of the Universe and that all matter was composed of four basic "elements" earth, water, air, fire. A fifth element, called aether, did not interact with the other four, but instead formed the heavenly bodies.
Ever since the Big Bang, the Universe has been drifting and expanding. The birth and death of stars leave an aftermath of galaxies, planets, and even living organisms.
THE BIRTH OF THE SUN
It was five billion years ago. A giant cloud of matter in our own galaxy, the Milky Way, condensed under its gravity, exploding in nuclear fusion.
THE LIFECYCLE OF OUR SUN
The Sun is currently stable, about halfway through its lifecycle. It's estimated it will live for about another five billion years before consuming all the hydrogen in its core and transforming into a red giant.
OUR SOLAR SYSTEM
forces flatten a young solar system and it begins spinnign as a disk of gas and dust. the middle of it may still feel off the material calapsing around it and continue to grow.
HOW DID THE PLANETS FORM?
New elements, combined with the just-right Goldilocks Conditions came together and formed our Solar System.
Though Earth was neatly orbiting the Sun as a rocky mass four and a half billion years ago, no organism could survive there. Radiation from the recent supernova kept the planet extremely hot, its surface molten, and oxygen was non-existent. Plus, incredibly massive meteorites and asteroids frequently slammed onto the surface — creating even more heat.
It took billions of years for the Earth to form and settle into orbit around the Sun.
Light travels fast. In one second it races around the Earth seven times. Then in a blink of an eye, light reaches the Moon.
Touching the edge of the Universe
In the scale of the Universe, light would take eight minutes to reach the Sun. And four years to reach Proxima Centauri, the next nearest star.
Different elements joining, colliding, breaking apart, and joining again is a very ferocious stage in the life of any planet. Even after the Earth formed, when the atmosphere began to stabilize, it was under siege. Early microbes, in their struggle for life, clashed with and consumed hydrogen gas. Hundreds of millions of years passed. These microbes evolved into prokaryotes and adapted further, finding energy in sunlight. Then, in a process called photosynthesis, they flooded the atmosphere with oxygen.
Naming the biosphere
Combining "bio," meaning life, and "sphere," referencing the Earth's rounded surface, English-Austrian Geologist Eduard Suess coins the term that expressed the portion of the Earth that supports life.
Along the edges where the continental and oceanic crust plates meet, all sorts of crazy things happen. These massive plates scrape past each other sideways. They dive under each other. And in places, they get snagged, causing tremendous pressures to build. When this tension suddenly releases things happen much, much faster than two centimeters per year.
While other scientists put forth the theory that the Earth's landmasses had once been connected by land bridges that had since sunk into the ocean, and had always been located where they are today, a few renegade scientists postulated that the Earth once contained one huge supercontinent. In 1858, Austrian geologist Eduard Suess postulated a supercontinent called Gondwanaland, and American astronomer William Henry Pickering suggested in 1907 that the continents broke up when the Moon was separated from the Earth.
It can metabolize, self-regulate, reproduce, and adapt. We also know that life is fragile in the face of gradual and sudden changes to the environment
The great oxidation event
A huge number of prokaryotes rose from the ocean and flooded the atmosphere with oxygen, a by-product of photosynthesis. While poisonous for many species, new life forms thrived in the oxygen-rich atmosphere, which also protected life forms from the Sun's harmful ultraviolet rays.
THE EARLIEST LIFE FORMS
some of the earliest life forms develpoed around deep sea vents
As new complexities start to populate the air, sea, and land, it might be a good time to ask, "What's the difference between non-life and life?" What is the difference between a mountain and a whale? Both are made of molecules. Both engage in chemistry. And both change through time.
A wide range of traits can be naturally selected for, depending on the environmental niche: for example, camouflage, burrowing skills, bright plumage, acute hearing, or the ability to retain water in desert climes. Yet sometimes events on Earth are so catastrophic that a large portion of its species may die off — making room for newly formed life.
What causes mass extinctions?
The discussion about what causes mass extinctions continues. While scientists do not yet fully understand the reasons, some of the possible explanations are:Sudden massive volcanic activity, as evidenced by vast lava plains whose dates coincide with extinction eventsRapidly changing climateImpact or multiple-impact eventsAnoxic events (the middle or lower layers of ocean becoming deficient or lacking in oxygen)Ever-changing position of oceans and continents (plate tectonics)
The history of our planet along with clues about its future is written in the layers of rock. Rock detectives or as they prefer to be called, geologists study these clues about the past and can also observe Earth's current changes firsthand.
The crater of doom
In 1950, oil geologists had noted the unusual features of a crater in the sea off of Mexico's Yucatán Peninsula. They thought it was a buried volcano. When the K-T boundary geologists learned about it, they were able to prove it was their meteor impact site.
After a major extinction, the weakest DNA dies off, while strong DNA is retained. But how it happens still puzzled biochemists by the middle of the 20th century. They accepted that creatures evolved like Darwin suggested, but still needed to figure out how parent organisms pass traits to their offspring. Most acknowledged that DNA, short for deoxyribonucleic acid, delivered the instructions. Yet they were baffled about its structure and how it worked.
Chromosomes in a cell
In human cells, long sequences of DNA are contained in chromosomes. These chromosomes are packed inside the nucleus of the cell, protecting this important genetic information. DNA is so tightly wound within a chromosome that the 51 million to 245 million base pairs in one human chromosome are estimated to be up to two meters long unraveled.
TREE OF LIFE
It was first believed that humans represented the pinnacle of evolution. But as biologists continue to study life on Earth, and as new species are discovered and more evidence comes in, the Tree of Life will continue to grow.
About 200,000 years ago, we evolved to become the most important force for change on the planet. Our knack for collective learning — preserving information, sharing it with one another, and passing it to the next generation — helps us create entirely new forms of complexity.
Crash Course Big History takes a look at Humans, one of the weirdest examples of change in the Universe. Around for only 250,000 years, we are truly one of the most complex things in the cosmos.
Humans had to use collective learning to come up with new adaptive strategies as they migrated in search of food, moving into environments they had never experienced before. They also altered landscapes and hunted many species to extinction.
WRITING AND SAVING KNOWLEDGE
Writing likely originated as a system of accounting as elites and power brokers who were accumulating more and more resources tried to keep track of their wealth. Eventually, the symbols used for accounting evolved to convey all the nuances of everyday languages and generate literature, history, and proper writing.
At the end of the last Ice Age, many humans decided to stay put instead of migrating any further. Communities grew denser and they had to draw more resources from a smaller area. Using their learned knowledge from the environment, humans began to experiment with agriculture, which became a revolution. Farming produced a surplus of food, allowing others to take up new work. Societies became diverse, populations exploded, and collective learning thrived.