The first second after the Big Bang is the most important second in the history of everything. Not the first million years. Not the first hour. One single second — and within it, the entire fate of matter, energy, and life was locked in forever. Most people know the Big Bang happened. Space expanded, stars formed, galaxies drifted apart, and here we are 13.8 billion years later asking questions about it. But the Big Bang itself is almost beside the point. What happened in the first second after Big Bang is where the real story lives — a story so violent, so strange, and so cosmically decisive that our existence today traces back to fractions of a moment too small to name. Here’s what actually happened. The First Second After the Big Bang: A Timeline of Everything NAOJ, CC BY 4.0, via Wikimedia Commons Before we go second by second,…