How much do you know about time travel? Like most people, you may have a few mistaken ideas about the subject. So before you can think about traveling through time, you need to know the truth about time trips. Here are two mistaken ideas about time travel:
Nothing could be further from the truth.
Did you ever stop to consider that everyone travels through time? Think about it: every day, twenty-four hours a day, everyone travels through time in the direction of the future. Of course, this isn't the kind of time travel that people imagine when they hear the phrase "time travel." Rather, they think of real time travel as a dramatic leap to the future or the past using a time machine. What about the possibility of real time travel? Not only is it possible, but it occurs regularly.
Many people who assume that time travel is impossible also make the mistake of believing that it's something only children think about. In fact, the idea of real time travel has intrigued many scientists, including Albert Einstein and Thomas Edison. For example, Edison believed that spirits of the dead--along with every word ever spoken--exist in the world around us. Although some individuals with heightened sensitivity hear these voices, Edison wanted to help everyone else by inventing a special radio that could tune in to past times. In 1920 he said, "I am at work on the most sensitive apparatus I have undertaken to build." Even though nothing came of his attempt, his interest in the subject was clear.
The idea of the time machine may have become a permanent fixture in the world's imagination after the publication of H. G. Wells's classic novel The Time Machine. His time machine was a simple one; two levers controlled it. One sent it into the future, the other into the past. Exactly how the machine was able to travel through time was never described in detail, but then Wells's book was a work of imagination, not fact.
At the beginning of the novel, the time traveler shows a small model of his machine to a group of friends. He then sends it on a one-way trip through time to demonstrate that the machine is real. One friend asks if it has traveled to the future.
The time traveler replies: "Into the future or the past--I don't, for certain, know which."
Another friend says, "I presume that it has not moved in space, and if it traveled into the future it would still be here all this time...."
But that friend's guess--that the machine travels in time but not in space--is one important reason why time machines seem to be impossible.
Einstein's Theory of Relativity explains why. In it, he proposed--and later proved--that time and space cannot be separated. Therefore, a time traveler must really be a time-and-space traveler.
Imagine, as writer John Gribbin did in his book Timewarps, that a time traveler decides to go half a year backward in time to the same location. He steps into a time machine, adjusts the controls to the right day and time, activates the machine, makes the trip, and steps out of the machine.
Where will the time traveler find himself?
Gribbin answers the question by saying that the time traveler will step into "empty space--since six months ago the Earth was on the other side of the Sun in its year-long orbit! A time machine must also be a space machine if our hero is to get anywhere he wants."
H. G. Wells's time machine never considers the relationship of space to time travel either.
Neither does one of the most famous fictional time machines: the DeLorean automobile converted for time travel use in Back to the Future relies on some vague mechanics, with its "flux capacitator" and plutonium fuel source.
Here are two specific problems with time travel as shown in the movie:
1. Dr. Brown, the scientist who invents the time machine, confuses time and space travel. When Dr. Brown demonstrates an elaborate clock on the dashboard to Marty, he says that they could witness the signing of the Declaration of Independence if they set the clock to July 4, 1776. The problem is that the two characters are in Hill Valley, California, and the machine has no mechanism for setting the destination of Philadelphia, Pennsylvania. Consequently, the DeLorean can only travel to the same location in the past or future. If they set the clock to 7/4/1776, how would they get to Philadelphia?
2. The location of the Twin Pines Mall changes in the movie. When Marty begins his time trip at the mall, he finds himself (some thirty years earlier) crashing into a farmer's back about two miles from the center of Hill Valley, In other words, the mall and the farm occupy the same land thirty years apart. But when Marty returns to the mall at the end of the movie, the distance between the center of Hill Valley and the mall is much less than two miles, so much less that he can run to the mall in a few minutes' time.
These two problems may be the result of careless movie-making. Or it may show just how hard it is to portray believable time travel in a movie. Watch the movie or its two sequels yourself and see if you can find other time travel problems.
Now that you know the mistaken ideas about time travel, you may be wondering how real time travel works. According to John Gribbin, real time travel seems to be possible "with or within the mind." He writs that time warps do not exist, but traveling through time does not require the use of a special machine--other than your own mind.
Real time travelers recount using much more normal travel means. First, many people have visited another time or place in their dreams. Others have said that they somehow "saw" another time. Still others have heard voices from another time. Finally, a few people even claim to have lived in another time--during an earlier life; whether their claims are true, though, is another matter.
Copyright © James M. Deem. Adapted from How to Travel Through Time (New York: Avon, 1993). All rights reserved.