A Short History of Nearly Everything Summary & key ideas explained

Somewhere over the Pacific, on a long flight, Bill Bryson looked down at the ocean and had an uncomfortable thought. He didn't know why the sea was salty. He didn't know what was under it, or how anyone had found out. He had lived his whole life on this planet and knew almost nothing about it.

The feeling went back to childhood. As a boy he'd pored over a school science book with a cutaway drawing of the Earth, a wedge sliced out of it like a piece of cake to show the layers inside. All he wanted to know was: how do they know that? The book never said.

So Bryson, a travel writer famous for being funny about places, spent about three years reading science books and pestering experts with simple questions. The result, published in 2003, is a tour of nearly everything: the birth of the universe, the weight of the planet, the age of the rocks, the atoms in your body and the long, lucky chain of life that ended in you.

It's not a textbook. It's a story about how we know what we know, and about the wonderfully odd people who worked it out, often by accident, often without credit, and sometimes at great cost to themselves.

A few facts have moved on since the book came out, and we'll flag them as we go. The big picture hasn't. So where does nearly everything begin? With something smaller than you can imagine.