The Big Bang was the starting point of the universe as we know it, an unfathomable reaction that came from complete nothingness and is responsible for the creation of everything. But what happened to the universe after the big bang?
Around 380,000 years after the Big Bang, gravity began to pull together hydrogen and helium, forming vast clouds that became increasingly hot. Eventually, the enormous pressure and temperatures in these pockets of gas created the first stars, flaring into existence around 100 million years after the big bang.
From here, a cascade of reactions continued to occur, forming heavy elements, planets, galaxies and finally; organic life, coming together to resemble the universe we observe today.
From Crash Course: Big History on YouTube presented by Hank and John Green.