A friend of mine just made this video on How to Build a Time Machine—not exactly a how-to manual (we’re millennia away from setting up shop), but an excellent summary of what we know and don’t know. It had me flashing back to befuddling physics classes of trains speeding past spaceships at faster-than-light velocities and timey-wimey wormholes. On a happier note, some of the best books I’ve ever read depend on time travel for plot.
My intro to the concept was Madeleine L’Engle’s A Swiftly Tilting Planet, which confused the heck out of me. I ended up reading it twice, and even drew little family trees on index cards (didn’t help). Planet belongs in the changing history category—the kind where time travel is used to alter the present, like in Harry Potter and the Prisoner of Azkaban. These tend to be the most confusing, since you end up with mind-bending paradoxes.
Then you have books like Rebecca Stead’s When You Reach Me, where the time-travel has already “happened,” so you have to piece together the events that led up to the altered yet existing present. Another would be Dirk Gently’s Holistic Detective Agency by Douglas Adams, so intricately plotted that it begs a second reading right after you finish the first.
Much less taxing on the brain are the books where time travel is treated as an adventure, like traveling to a foreign country. L’Engle’s Many Waters falls squarely in that box. The main characters still face peril, but what they change in the past has no direct effect on their own present. Silver on the Tree by Susan Cooper has a similar concept, except with tighter connections between time periods.
I call the last category Time Travel as a Spectator Sport—something like Ender’s Game or Ender’s Shadow where the protagonists observe the effects of faster-than-light travel on others. Not so much traveling through time as cheating time, but still cool. So these are the time travel books I remember the most. What about you? Is there anything that gave you a headache? Or jaw-dropping examples that made you read the book twice in a row, just to catch all the clues and details?