If there’s one thing science-fiction writers love as much as the idea of exploring space and meeting aliens, it’s traveling back in time and screwing things up. From H.G. Wells to the recent reboot of Star Trek, time travel is one of the genre’s most well-explored tropes, but authors keep finding new ways to spin it. The brand-new anthology The Time Traveler’s Almanac encapsulates that storied history, collecting nearly seventy tales of altered timelines and unresolved paradoxes, from the theme’s roots to its latest twists. To celebrate the book’s release, three local contributors — Jason Heller, Connie Willis and Carrie Vaughn — will be signing and reading from it, as well as discussing what makes time travel so special.