And for those humans who survive, it means that your perspective of existence is about 80 years. Out of 13.8 billion. We don't live long enough to perceive our origins, or how much in our universe has changed. Our eyes can only see to a certain visibility, so everything at the atomic level appears invisible. Our eyes can only see to a certain distance, so our universe looks much smaller than it really is. In one lifetime, we'll only get the slightest glimpse of how the universe plays out. Science can help us see into the past, see far away, and see down below.
Tyson starts in the Permian Period, about 300 mya (million years ago). The constellations we know would not have existed. Earth itself was unrecognizable. Oh, it was blue and green, but Permian astronauts would have seen a very different world than what Neil Armstrong and Buzz Aldrin saw:
One continent. Giant Bugs. No cable.
Insects swarmed the Permian landmass known as Pangaea. It was the last time our world was really united, and it created lasting mysteries in the fossil and geological record. But how did we realize it existed? How did we explain its forming, and its breakup?
The Permian diversity of life was made possible by a new innovation in living things: trees. Mutation at the molecular level produced lignin in plants, enabling them to be strong, yet bendable. This allowed for plants to grow up, instead of out, collecting more light as they got taller and higher. The result: more trees made more photosynthesis. And more photosynthesis produces more oxygen as its waste product. Oxygen in our atmosphere abounded. Any living things that survived by inhaling oxygen through their outer shells thrived, and had the potential to be huge. Dragonflies had 24" wingspans.
Yeah. Go ahead. Try the bug spray.
What happened to the trees, as they died? Well, lignin was hard for animals and surface microbes of the time to digest, so the trees sat and decayed, leaving behind fossils for us to find. Over time, they were buried, and the carbon dioxide in their decaying shells was buried with them. The decaying process literally turned these dead trees into our world's current coal, oil, and natural gas supply.
Exxon is basically dead trees.
This awesome spectacle died, pretty quickly by fossil record standards, starting at about 252 mya. With Siberia. Basically, volcanoes set a huge supply of fossil fuel coal on fire over an area the size of Western Europe. What is known as Siberia today literally erupted. For years on end, volcanoes spewed lava and ash. The lava alone covered about 2 million square kilometers. The ash spread throughout the atmosphere. Siberia's coal (a fossil fuel from all the trees) combined with the ash, produced sulphur and radioactive ash particles, aka coal smoke. Imagine London, in one of their coal-induced pea soup fogs. The haze blocked the sun and caused temperatures to immediately plummet. But that's not all. The CO2 realized by both volcano eruptions as well as the igniting of all that coal starting a chain reaction of massive global warming, soon overpowering whatever creatures hadn't died from the freeze.
As the waters warmed, the change in surface water temps caused massive current changes, churning bottom and top water. This churn, and warmer water near the ocean floor, melted huge chunks of methane ice. And methane is an even more potent greenhouse gas. As methane ice melted, then evaporated, our atmosphere retained even more heat. In addition, methane gas then destroyed the ozone layer of the time, exposing all living things to the worst of the sun's UV radiation. Eventually, oxygen literally ran down, as plants producing it died out. It was like a perfect storm to end all life on Earth. And it almost did. The Permian-Triassic Extinction is the worst mass extinction known in our planet's history. About 90% of our world's species died out. Only small things lived, things that could survive the heat, the low oxygen, and the extra radiation. Our planet's Tree of Life took about ten million years to recover.
Living things looked very different in a period of 10 million years. So, our perspective of biodiversity is missing the branches lost from the Permian. It requires careful looking at the fossil record to understand just how many different living things the earth can support. But the fossil record and the geological sediment record seemed to be fucking with us. Fossils of identical animals could sometimes be found on both Africa and South America, from the same time period. How could identical animals have lived at the same time across thousands of miles of oceans? How could mountain ranges appear and disappear, and appear to cross oceans as well?
People have noticed, since maps were first made, that Africa and South America look like long lost puzzle pieces. Abraham Ortellius, producing a map in 1570, guessed that the two continents were once united, and chalked it up to earthquakes or floods. Alfred Wegner, an early 20th century meteorologist, guessed almost correctly, giving us the idea of continental drift, the idea that continents move. But how, how does higher solid land move across the ocean floor? With limited views of the world, without a proper idea of what was beneath our own feet, we could not imagine how Wegner could be correct.
In 1952, Bruce Heezen and Marie Tharp collaborated on a project to map the floors of the oceans. Using sonar onboard ship, Heezen collected data on elevations all over the ocean floor. Tharp was restricted from conducting her own research onboard, as women were not allowed. So, she took Heezen's data and processed it in New York, producing the maps. Marie noticed a mountain range right smack in the middle of the Atlantic Ocean, now called the Mid-Atlantic Ridge. First publishing a map of the Atlantic Ocean floor in 1957, they produced a truly worldwide map of the world, showing ocean floors as well as landmasses, in 1977.
Our real world
Once you can really see the world, you can literally see how it's stitched together, usually in our oceans, but also along the Pacific Coasts of the Americas and Asia. Like stitching on a baseball, these are the tectonic plates of Earth's crust. The crust of our planet, is like an eggshell to an egg- a very thin surface over all sorts of activity deep inside. This includes our liquid and solid cores, made of iron and other heavy metals, as well as an inside layer of mantle, literally hot lava under the crust, filling in the space between core and surface.
Basically, anything orange and red. We live where it's blue.
The mantle is constantly churning crust, because it's fucking hot and kind of liquid. The crust resists. Depending on who wins, the mantle or the crust, and how much energy has built up in their shoving match, landmasses can split or be scrunched together.
Just watch the movie. It's in color.
It requires something else to understand how our landmasses are shaped, and the effect on life that has. Not as catastrophic as the Permian Extinction, the breakup of Pangaea started about 175 mya. First, north broke off from south, into Laurasia (North America, Eurasia), and Gondwanaland (South America, Africa, Antarctica, Australia). Then, east and west split, as the Americas drifted together, separated by a sea where Central America is now, water moved around freely between Atlantic and Pacific. Plate tectonics changed that, shoving Panama up from the ocean floor where it is now, creating the ocean currents (and associated air streams) we currently know.
Plate tectonics created the Mariana Trench, about 6 miles deep (height of Everest, but inverted), with water pressure at about 8 tons per square inch. You and I can't live there, as it's too cold, too dark, and would crush us like bugs. But other things can. Lots of things. Without light, the animals of the deep produce their own through bioluminescence, which is using pigment, an enzyme, and oxygen to make light. Without plants, the bottom of the food chain hangs around vents in the ocean floor, imbibing hydrogen sulfide.
As if below isn't bad enough, above is even crazier. Venus isn't large, but it's close (relatively). Jupiter and Saturn aren't close, but they're fucking huge. Their gravity pulls and pushes at Earth, affecting our tilt and our orbit, creating the Milankovitch Cycles. Even a small change can produce an Ice Age, with glaciers covering about half of the Northern Hemisphere. But we've survived them. As a species, not as individuals. The last ended about 20,000 years ago. But we have no records from our ancestors about surviving them. We had to learn about them from fossil and geological records, which are the true survivors. The next isn't expected for another 50,000 years from now. Tyson hints that the Halls of Extinction have our next chapter. Well, not ours. So, about 70,000 years will exist, in which humanity has a nice weather window. On a 4.5 billion year-old planet. In a 13.8 billion year-old planet. Our tiny perspective is from when the sun is shining, not from when the perfect storm comes.
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