Undarkened Doors

The speaker discusses their PhD research on nuclear winter, highlighting the challenges faced due to isolation and a small research community. After completing the PhD, they engaged in various voluntary activities, including work with anti-war organizations and charities. Despite initially vowing not to return to physics, they were drawn back by a compelling topic in solar energy.

What was the speaker's initial reaction after finishing their PhD?

What was the significant topic that emerged from the speaker's research?