You are holding something solid. A book. It has weight. Push it; it pushes back. Drop it on your foot and you will know what mass means before any physicist has finished explaining it.

Now ask the question almost nobody asks. Where does that weight come from? Not the book. The matter the book is made of. The atoms. The particles inside the atoms. The little buzzing things inside those particles. Where does any of it get the property of being heavy, of being there, of refusing to vanish when you look away?

The honest answer is that physics has three answers, and they do not match.

This book offers a fourth one. A simpler one. The universe, it turns out, does something that looks remarkably like what a video game does when it draws a world on your screen. It renders matter out of an empty-looking background. Most of what you call empty space is not empty at all. It is fizzing. And every so often, a little piece of that fizz gets locked in place and refuses to disappear. That locked-in fizz is you. It is your phone. It is the moon.

Emerson King wrote a technical article about where mass comes from. This book is the friendly version of that article—the same ideas, told the way they should have been told all along, for listeners who want the answer without the equations. No assumed background. No condescension. Just one very good idea, and a tour of the universe through it.

No math. No assumed background. No condescension. Just one extremely good idea, told the way it should have been told all along—quickly, clearly, and with as many jokes as the subject can bear.

If you have ever wondered what the universe is actually doing when nobody is watching it, start here.