Paul J. Nahin, Time Travel

Science Fiction Writing Series; Ben Bova, ed.

reviewed by Danielle L. Parker

Any serious — as in seriously interested — speculative fiction writer should probably have Ben Bova’s Science Fiction Writing series on the shelf. Time Travel is, of course, one in the series, and the other is Space Travel.

The two books should keep you from making some of hilarious non-scientific bloopers described in Nahin’s interesting history of the genre. Since time travel stories have been around at least since Edgar Allen Poe wrote “Three Sundays in a Week” in 1841 (note this story pre-dates even H. G. Well’s classic of 1895, The Time Machine), it’s no wonder the early pulp stories were full of pseudo-scientific gobbledygook. Many of those early stories made no pretense of scientific correctness at all, of course: Mark Twain relied on the good old head-bash in his A Connecticut Yankee in King Arthur’s Court; many others invoked the Devil, that jaunty, traveling gentleman; others, like Rip Van Winkle and Sleeping Beauty, drowsed their way into the future (or the past).

But if you should want to try your hand at time-travel mechanisms Einstein might have grudgingly nodded at, Nahin has the writ. First, though, we have to deal with concepts of time, which in turn relies on concepts of the universe. We’ve all heard of Einstein’s discovery of the relativity of time, which basically says that moving clocks run slower than stationary clocks (which is called time dilation). Next, we get into Minkowski’s four-dimensional world-points (a point of space at a point in time, with time, of course, being the fourth dimension) and hyperspace (which is a space of higher dimension than the one we live in).

Once we embrace the concept of time as the fourth dimension, Nahin examines alternate versions of time, such as circular or helical. One of the more interesting views is the block universe. To illustrate the block universe concept, Nahin gives the example of a man drifting down a river in a boat. The boater passes a row of houses as the current carries him onward, which is how he perceives time (i.e., as a sequential flow of events, like each house he passes). But now imagine a viewer who is up in the air. The viewer above the scene — who is outside the four-dimensional space — sees the whole row of houses, the river, and the man in his boat at once. To this viewer, Time is all one; this might be called God’s view of time, in the block universe model. It’s a fascinating thought.

In the latter half of the book, Nahin covers theoretical time machines in more detail. There are several options. The first option is a rotating black hole, through which a theoretical traveler could pass to another universe or time. There’s Tipler’s rotating cylinder, which could cause a distortion of space-time, as another option (although it would only allow the traveler to go into the future, and there is a problem with actually building a near infinitely-long cylinder that rotates at near light-speed, no one seems to disagree that it would work). Nahin thinks wormholes, his third option, are actually the most likely candidates for working time machines, but he lists one last candidate, cosmic strings (which have not been much used in fiction so far, apparently: go for it!).

Want to know more about how these theoretical time machines really work? Check out Nahin’s book and find out, and get to writing those time travel stories for our story contest!

Copyright © 2006 by Danielle L. Parker