Towards the end of Chapter 4, Jacob’s father remains adamant of his view of Grandpa Portman. What does he resolve and somewhat convince Jacob of as the reasoning for Grandpa Portman’s lack of presence as a father?

radiative zone

explanation    

radiative zone is the layer of the sun which energy is transferred away from the core by radiation. although, the core is the only part of the sun that produces an appreciable amount of heat through fusion. in fact, 99% of the energy produced by the sun takes place within 24% of the sun's radius.