The Beginning of the Universe:

Age of the Universe: 13.8 billion year
It is just as easy to say “the universe was 1 second old” as it is to say “the universe was 10 billion degrees celsius”
It’s called the “Big Bang” for a reason, this would have been the most cataclysmic explosion ever.
The earliest moment: A Planck Epoch
At about a billion billion billion billionth of a second in, the three primary forces (electromagnetic, strong and weak nuclear force) of the standard model would be about to separate from one unified force.
After about a trillionth of a second, the universe starts to take on properties that are well represented by the standard model and has reached temperatures of about a thousand trillion degrees celsius which we can test in the lab.
However, at about a 10,000th of a second as the universe cooled to about 10 billion degrees, protons and neutrons could start to form. These are the building blocks that make up us, once they join together to make atoms, but that isn’t for a while yet.
After less than an hour from the big bang things get pretty boring. The universe has expanded enough that atoms don’t collide with each other enough to build up to bigger atoms, so mostly the universe is a big ball of very consistent plasma.
It’s important to emphasize how consistent the plasma is, fluctuations were on the scale of one in 100 thousand. So at this point the universe is about 10 million degrees and from one point to the next the temperatures are exactly the same except by about a hundred degrees. That’s very smooth!
As the universe cools to about 4000 kelvin, crossing just below the temperature of the surface of the sun, it is finally cold enough for electrons to match up with the hydrogen/helium to form neutral atoms. This happens after about 300,000 years.

Special thanks to Colin Vendromin for the music, also thanks to Zac Kenny for the logo!