Time Travel

"Don't tell me about the future," said Ford. "I've been all over the future. Spend half my time there. It's the same as anywhere else. Anywhen else. Whatever. Just the same old stuff in faster cars and smellier air." (From "Mostly Harmless", 1992, Book Five in the Hitchhiker's Trilogy by Douglas Adams.)

Time travel is a common theme in dimensional literature. Since the word on the street is that "the fourth dimension IS time," this is unsurprising. In Math 08, we've learned something about what else the fourth dimension can be, but time is perhaps the most readily accessible definition. Many fiction and fantasy writers have explored this aspect of the fourth dimension.

In Madeleine L'Engle's "A Wrinkle in Time," three children are transported off of their planet and travel by "tessering." ("Tesseract" was a popular synonym for "hypercube" in the early decade s of the twentieth century, when the fourth dimension was just beginning to be seriously examined by geometers, philosophers, etc; the term show up many times in the Scientific American volume, "The Fourth Dimension Simply Explained" [1910].) In L'Engle's story, the children and their guides "tesser," which means that they travel in the fifth dimensiončassuming the fourth dimension is time, in time squared. The description of this squaring of time is physical: the multidimensional tour guides can somehow fold time up, like a piece of cloth held between two hands, so that in no time at all they can move from one point to a distant one [see discussion in "Children's Literature"].

(Of course, the ultimate transdimensional force in "A Wrinkle in Time" is love. The heroine, Meg, is able to save her little brother Charles Wallace from spiritual possession and thought control by the sheer energetic force of her affection for him. Bu t, while love may be higher-dimensional, it is difficult to quantify and to examine mathematically.)

In his Hitchhiker's Trilogy, Douglas Adams explores some of the more comic aspects of time travel. One character accidentally becomes his own great-grandfather because of "an accident inv olving a contraceptive and a time machine." Adams deglamorizes the whole idea of time travel by suggesting that, if and when humans do learn to travel forward and backward in time, they will use that ability to do things like put white-out on rough drafts of classical poetry and find new and better ways to get drunk and sell things.

In "Mostly Harmless", the fifth book in the Trilogy, Adams has one multi-dimensional character suggest that "....in your universe you move freely in three dimensions that you call space. You move in a straight line in a fourth, which you call time, and stay rooted to one place in a fifth, which is the first fundamental of probability. After that it gets a bit complicated."

This raises a bunch of questions: Why are we less mobile, instead of more so, as dimensionality increases? Why is probability what we are rooted in? Adams toys with this idea a lot; his spaceships are powered by something he calls Infinite Probability Drive. Playing with numbers, Adams suggests, generates its own kind of weird energy. But he mocks, over and over again, people who take such games too seriously.