SB law describes the relationship to power density of a surface and corresponding temperature; it just gives you an idea of the equivalent temperature sans active cooling. For the brain that temperature is just similar to a dark surface receiving constant sunlight, so it’s not a serious cooling challenge.
That section was admittedly cut a little short, if I had more time/length it would justify a deeper dive into the physics of cooling and how much of a constraint that could be on the brain. You’re right though that the surface power density already describes what matters for cooling.
SB law describes the relationship to power density of a surface and corresponding temperature; it just gives you an idea of the equivalent temperature sans active cooling. For the brain that temperature is just similar to a dark surface receiving constant sunlight, so it’s not a serious cooling challenge.
That section was admittedly cut a little short, if I had more time/length it would justify a deeper dive into the physics of cooling and how much of a constraint that could be on the brain. You’re right though that the surface power density already describes what matters for cooling.