To a certain extent, loneliness is part of the human condition. You can be lonely anywhere, even surrounded by friends. But modern life has exacerbated it, and that requires modern solutions. Indie game designer Jason Rohrer has one — an artificial friend named Samantha.

Journalist Elizabeth Becker, the author of "Overbooked: The Exploding Business of Travel and Tourism," breaks down how we got to this moment in global tourism, and how we might nudge nations, companies and ourselves to become more responsible travelers.

For her own book, author Ruth Ozeki drew from “Kamikaze Diaries,” a collection of writings left behind by the young soldiers who died on suicide missions. They represent a generation of brilliant, highly educated young students who were conscripted into the army and ordered not just to kill but to die.