Origins: Fourteen Billion Years of Cosmic Evolution

Neil deGrasse Tyson and Donald Goldsmith wrote this book as a companion to the series Origins, which aired on the American public TV program NOVA in 2004. The thread running through the whole book is the idea of cosmic evolution: the passage from a simple, uniform universe right after the Big Bang to the universe full of complex structures that we see today, with galaxies, stars, planets, and, in one small corner, people.

The starting point is a universe that was born already expanding, extremely hot and dense, about 13.8 billion years ago. The book's title rounds that number to fourteen billion, which is easier to keep in your head than the exact decimal.

It's worth understanding right away that the Big Bang was not an explosion inside an empty space that already existed, like a bomb going off in a room. It was space itself that began to stretch, carrying along everything that existed within it, including time.

In the extreme heat of the first instants, pure energy turned into pairs of particles: one of matter and one of antimatter, twins and opposites. When one of those pairs met again, the two annihilated each other and turned back into energy, a constant cycle of creation and destruction.

If the amounts of matter and antimatter had been exactly equal, the book explains, the end result would be nothing but light left in space, with no matter left over to form a star, a planet, or anything solid. For anything to really exist, it depends on a tiny imbalance: for every billion pairs that canceled out, one particle of matter was left with no partner to destroy it.

This small leftover, now called the matter-antimatter asymmetry, is an observed and well-established fact. The exact reason it happened in that specific proportion, though, the authors treat as an open question, not a fully solved mystery.

For the first 380,000 years, the universe was opaque, a dense soup of charged particles that scattered any light before it could travel far, a bit like a flashlight beam that can't get through milk boiling in a pot.

When that soup cooled enough, electrons joined atomic nuclei and formed the first neutral atoms, a process scientists call recombination. At that moment the light was finally free to travel, and that same light is still arriving today, stretched by the expansion of space until it became microwave radiation: the cosmic microwave background, the oldest picture we have of the universe.

This radiation was mapped in detail decades after the Big Bang theory was proposed, and it confirmed specific predictions made before the measurement. That is why the authors have so much confidence in this part of the story, unlike the more speculative stretches that appear later in the book.