"Silence is uncomfortable"
Start with the belief that's true, because the rest of the book depends on being honest about it.
Timothy Wilson and colleagues, in 2014, ran eleven studies in which people were asked to sit alone in a room for six to fifteen minutes with nothing to do but think. Most didn't enjoy it. Given the choice, they preferred mundane external activities, and in one study, a good proportion chose to give themselves a mild electric shock rather than sit with their thoughts, including people who had earlier said they'd pay to avoid the shock. The researchers' conclusion was that most people would rather be doing something than nothing, even when the something is unpleasant.
An earlier book in this series, about the phone, uses this study to grant that empty moments are genuinely uncomfortable, and I'm using it for the same reason. The itch is real. You're not imagining it, and you're not weak for feeling it. A room with nothing in it produces, in most people, a restlessness strong enough that a shock seems preferable, and a walk to the car with no podcast produces a smaller version of the same thing.
But look at what the study measured. Six to fifteen minutes. People who'd been told to sit and think, in a bare room, with the instruction that they should entertain themselves with their thoughts and nothing else. That's the itch at its worst, and it's a fact about the first minutes of quiet in a strange setting for people who weren't used to it. It isn't a fact about quiet as such, and it isn't a verdict on what happens after the itch, because the study didn't run long enough to find out, and neither, if you've filled every minute for years, have you.
So the belief is right about the first minute and wrong about what it means. Silence is uncomfortable, at first, for almost everyone, and the discomfort is what the fill has been treating. What the fill has also done is make sure you never get past the discomfort to find out whether anything follows it. Chapter 16 is about how the itch behaves when you stay with it for a few minutes longer than Wilson's participants were asked to, and chapter 18 is about what turns up on the other side.