The week I was supposed to go to France, an article about my old favorite TV show, “Lost,” popped up in my Facebook feed. The article reflected on an episode that premiered a decade before and centered on time travel—a popular theme for “Lost” if you were a fan. In particular, the article mentioned the difficulty in writing the episode because time travel presents several paradoxes that either must be assumed impossible or else time travel must be assumed impossible.

The Grandfather Paradox stuck with me – essentially, you must believe there are certain truths that cannot be altered by time travel. For instance, you can’t kill your grandfather (before at least your parent is born), or else you forfeit your own existence, but you can’t not exist if you are the one changing your own future.