15 billion years ago, there was nothing.
No trees, no people, no water, no Stanford football team to annihilate.
There was no time, no dimensions, and no Doctor Who (although, I’m sure he’s visited).
14 billion years ago, there was a Big Bang (…If a universe suddenly exists, and no one is around to hear it, does it still make a sound?).
Seconds after the Big Bang occurred (time didn’t exist before it!), the universe became a hot, sticky, primordial Campbell’s soup of stuff flying around with no order or intention. Then the universe started to cool, and existence began to order itself into the building blocks that we know our world to be made of – protons, neutrons, electrons, atoms, etc.
Then began the formation of stars, and from stars came galaxies, then supergalaxies. In the cores of those many stars elements were born from the fusion of nuclei under intense heat and pressure. (Yes, the atoms that create you were formed in a star.)
Fast forward nine or ten billion years (or…about as long as a 50-minute calc’ class feels), and you’ll find the creation of our home sweet home, Earth. The Milky Way Galaxy had already formed, spinning precariously around its black-hole center and containing more than 100 billion stars.
On one edge of the Milky Way, a bunch of rocks and dust and particles started playing bumper cars – colliding and sticking together – and after a long time there was a rock big enough to be classified as a planetessimal. This hunk of rock is so huge that it develops its own gravitational pull (yo’ mama joke, anyone?), and attracts more rocks and dust, making a larger and larger proto-planet.
All over our solar system, other proto-planets are smashing into each other to create the planets we know today…well, other than Pluto; poor guy…
Meanwhile….
the sun sneezes and blows away all the leftover junk and gas floating around. The gravitational fields around larger planets hold some of the gas, creating the gas giants. Smaller planets such as Earth remain rocky.
Now Earth is spinning around and chillin’ out when, all of a sudden, another smaller hunk of rock slams right into it at such a force, that it takes a chunk of Earth with it!
We shall call this new chunk The Moon.
Because the Moon has no core, scientists are pretty certain that the Earth had already separated into its differentiated layers – the crust, mantel, core, etc. Scientists also know the Earth already had water on it by this time, because the Moon has water on it and the rocks that the astronauts brought back were around the same age as the Earth.
Fast forward another few million years, and you can watch a few badass thunderstorms electrify life into existence, observe fish crawling out of the sea, scales becoming feathers, and humans walking upright (While not 100 percent certain, scientists are pretty sure that the cast of Jersey Shore might have missed a few thousand years of evolution).
Finally,  you’ve got the modern Earth.
For all we know, the universe will expand forever and ever, and the Earth will continue rotating, orbiting, evolving, tilting, erupting, and shifting until the end of our time, and even into infinity and beyond…
…or will it? (Cue horns from Inception)
Next week: THE END OF THE UNIVERSE
*This is the name that Calvin, from Calvin & Hobbes, decided the Big Bang should be replaced with. All credit goes to Bill Watterson