There are a lot of things easier than writing a book that no one may understand in order to answer questions that most people weren’t even asking — and selling 10 million copies of it. Steven Hawking’s A Brief History of Time, published in 1988, did all of those things. The genius of Hawking was to understand that while people weren’t losing much sleep over such matters as event horizons, space-time geodesics and stellar contraction, they were deeply, primally interested in such questions as “Why does the universe go to all the bother of existing?” as he elegantly put it. In that riddle lives the smaller but more anthropocentrically relevant one, Why do we exist? Hawking provided answers — with hard physics, gentle metaphor, and ideas so big they fill up space itself. And you know what? We got it — and we’re smarter and better because of that.