John Wheeler once said, “Time is what keeps everything from happening at once.” I like to quote that to myself, usually around four a.m., when I’ve spent hours staring at an invisible ceiling, wondering why I remember so little of events before my fourth birthday and absolutely nothing of tomorrow’s. The sentence is short, succinct, at once profound and silly, and it provides enough comfort that I can generally roll over and drift off. Unless, of course, I’m thinking about time travel.

Thinking about time travel is almost unavoidable if you’re writing a book that involves trips to the past and future, and up until a few months ago, that’s what I thought I was doing. Then I realized my book, PLENUM, was really about time lines. You know, alternate histories in the multiverse, where you just won the lottery in some of them, but you’re dead in most time lines, and in all the others, you’re lying in the dark, wishing you’d just won the lottery, or at least could stop thinking about time travel.

So anyway, that’s how I forgot about time travel and finally settled into a good night’s sleep. But then I started thinking about that multiverse, really thinking about an infinity of possible worlds, some of them exactly like this one. That woke me up, and believe it or not, the multiverse is worse than time travel for keeping you awake at night. Fortunately, my book also has at least five different love stories in it, and nobody ever lost sleep worrying about love, right?