Scientists have stepped up their investigations into fake news in recent months. Amid all the analyses, studies and meetings, some have raised the possibility that a lot of people simply don't care whether the claims they embrace are true. "Post-truth" has become a hot topic for researchers from a variety of fields, including Nobel Prize-winning chemists: The annual Lindau Nobel Laureate Meeting in Germany this summer took as a theme "Science in a Post-Truth Era."

Skeptics have long studied why people wrongly believe in astrology, ESP and all manner of weird things, but not caring about truth at all would seem to fly in the face of basic human curiosity. People send probes to other planets, dig up dinosaur bones and build powerful microscopes to find out the truth about inner and outer space. Shouldn't curiosity act as a guardrail to keep us from falling into a post-truth world?

Astrophysicist Mario Livio makes a key observation in his new book, "Why?: What Makes Us Curious." To be truly curious requires a middling level of knowledge, he says. If you know absolutely nothing, then you don't know what to be curious about. If you know everything, you have no reason to inquire. So children who have never heard of dinosaurs can't be curious about them, and very few adults are curious about how many pennies are in a dollar.