02
Inside a Fusion Reactor
Pull the temperature up by a hundred million degrees and feel the exact moment matter agrees to fuse.
Fusion sounds like a wall of numbers: kelvin, plasma, confinement. But underneath it is one stubborn fact. Two nuclei do not want to touch, and only ferocious heat can change their minds. Here you hold the temperature dial yourself. Below a threshold, nothing. Push past it and the screen erupts. You are running a star with your thumb.
Notes from the making
The threshold had to feel like a threshold. I tuned the collision physics so that nothing dramatic happens until you’re genuinely close. Then everything happens at once. That cliff is the lesson.
A reviewer asked me to label the temperature in “reactor units.” I refused. The whole reason fusion is hard is that the number is absurd. You should feel the absurdity.