A common plot in science fiction, time travel is the concept of moving between different periods of time, either by sending people, objects, or information backwards to a time before the present, or forward to a future time. Some ideas of time travel involve moving between parallel universes. Most people believe that they have a good idea of what time is, but it’s actually more complicated than looking at your watch. No one actually knows what time is, so it’s difficult to know whether the laws of physics will permit time travel. In his famous theory of relativity, Albert Einstein treated time as the fourth dimension. He also referred to the speed of light as the speed limit of the universe, arguing that a speed that was faster than the speed of light would violate the principle of cause and effect. An example would be a bullet hitting the target before the trigger was pulled. However, if a spaceship were left earth for another planet, traveling at 10% the speed of light, time would pass more quickly for those left on earth than for those in the spaceship, and that effect would increase with the speed of the spaceship. Wormholes are viewed as another way of moving through space and time, and have become another favorite of science fiction. Currently, our spacecrafts are too slow and too heavy for us to travel far enough in space for the time differences to matter, but that might be a problem that we are able to solve at some point in the future. Another theory is that UFOs are piloted, not by extraterrestrials, but by human beings from the future. Someone coming from the future would likely take steps to minimize interference with people from our time period, which might account for the many sightings but few contacts that are reported. At some point in our future, perhaps human beings will discover that what we currently know about science is unnecessarily limiting, and will develop other modes of travel through time. Perhaps they already have, in their time.
Feature Article
Time Travel: Fact or Fiction?
Long the topic of science fiction novels, movies, and late-night radio,
the idea of time
travel falls into the same genre as Atlantis,
the Illuminati,
UFOs,
and the abominable
snowman, each of which many people believe to be real. In the case
of time travel at least, they are in good company.
Time travel is the concept of moving either backwards or forwards to
different points in time, and some very well respected people have
conceded its possibility.
In 1915, Albert Einstein proposed his well-known theory of relativity,
which argued that the universe consisted of four dimensions, the first
three being what we know of as space, the other being spacetime, in which
space and time are linked. Depending on their distance from the event,
Einstein proposed that two people viewing the same event, in the same
manner, could perceive the singular event as occurring at two different
times, depending on their distance from the event. Einstein theorized that
time travel would be possible, but only in one direction.
More recently, Stephen Hawking suggested that, although the idea of time
travel sounds far-fetched, it was not crazy. In fact, he discussed ways in
which time travel might be accomplished. Although he concluded that the
absence of time travelers from the future would be an argument against it
having ever been implemented, now or in the future, he did not go so far
as to say that it was impossible.
Several theories for time travel have been advanced over the years,
including traveling faster than the speed of light, which travels at
186,282 miles per second in a vacuum. Scientists at the Glenn Research
Center, a division of the National Aeronautics and Space Administration
(NASA), have pointed out that when a human being is traveling at speeds
close to the speed of light, time goes slower for them than for those who
are left behind on earth. If someone were to be on such a journey for five
years, it would be the equivalent of fifty years on earth. However, this
effect would not be noticed until they returned to earth.
Another theory involves the creation of wormholes between points in
spacetime. Although Einstein's theories provide for the existence of
wormholes, they would collapse very quickly unless the wormhole was what
has been termed a traversable wormhole, a yet hypothetical wormhole that
would allow travel in both directions, either from one part of the
universe to another part of the same universe, or from one universe to
another. In this theory, a wormhole would connect two points in spacetime.
However, theorists argue that it would be impossible to travel back to a
time earlier than when the wormhole was first converted into a time
machine.
Yet another is the Tipler Cylinder, which was a time machine proposed by
Frank J. Tipler, a physicist, in 1974. His proposed machine is a massive
cylinder, spinning along its axis, which would exploit a geometric oddity
of spacetime to create a closed, time-like curve. A spaceship accelerating
into it would travel backwards in time, although the limits to which it
could travel would be to the moment of the creation of the device.
Whatever the method, if time travel were to become a reality, it would not
come without problems and paradoxes, and certainly we would have to
reconsider how we think about our world and our existence in it.
Most of us, whether or not we are familiar with it as a scientific theory,
hold to the theory of presentism, which holds that neither the past or the
future exist, believing that the past exists only in the memories of those
who were there, and the records they left, while the future exists only in
speculation. This viewpoint would be inconsistent with time travel because
there would be no past or future to travel to, except in one's mind. Proof
of the possibility of time travel would force us to abandon this mindset.
The grandfather paradox was first described by Rene
Barjavel in his 1943 science fiction novel, Le Voyageur Imprudent
(Future Times Three), in which a time traveler went back in time and
killed his grandfather, before his grandfather had children. Therefore,
the time traveler is never born when he was meant to be. Of course, if he
is never born, he would have been unable to travel back in time to kill
his grandfather, which would mean that he would be born, and so on. A
similar paradox would be one in which a time traveler kills himself as an
infant.
These, and other, paradoxes and problems have been fodder for science
fiction novels and movies, as you might imagine. However, real people have
claimed to have been time travelers.
On August 10, 1901, Charlotte Anne Moberly and Eleanor Jourdain, both
academics, visited the Petit Trianon, a chateau on the grounds of the
Palace of Versailles, where they claim to have experienced a time slip, in
which they saw Marie Antoinette and others from the same period. They
published their stories together in a book that was entitled, "An
Adventure", under the pseudonyms of Elizabeth Morison and Frances Lamont,
in 1911, and were ridiculed for it.
One famous incident became known as the Philadelphia Experiment, which is
said to have been a naval military experiment carried out at the
Philadelphia Naval Shipyard on October 28, 1943. If the allegations are
true, the US Navy destroyer escort USS Eldridge was made invisible, or
cloaked, to enemy devices. The experiment was allegedly based on the
unified field theories of Albert Einstein. Reports are that the Eldridge
completely vanished from the area and was teleported two hundred
miles away, to Norfolk, Virginia, where it was seen before it reappeared
in Philadelphia, going back ten seconds in time in the process. The US
Navy maintains that no such experiment was ever conducted.
Another involves John Titor, as he identified himself, who began posting
on an online public forum on November 2, 2002, claiming to be a time
traveler from the year 2036. He posted photographs of his time machine, as
well as pages from the operation manual. He also posted on other forums,
and was a guest on the late-night, Art Bell radio show. On March 21, 2001,
he stated that he would be returning to the year 2036, and was never heard
from again. Since that time, a number of problems have been pointed out
with his story, including predictions that have subsequently not occurred,
and many have speculated that his story was a hoax.
A movie based on characters and situations told by John Titor was produced
by Cydonia Pictures in 2010. Presented here is a movie trailer, a synopsis
of the story, the film treatment, cast, photographs, and an overview of
the John Titor story.
There are others, but none of these stories of genuine time travelers
appear to hold up well in the light of the evidence.
What then, are we to think of time travel? We cannot know for sure, but it
would seem that, although the evidence is strong for time travel as a
theoretical possibility, there is little compelling evidence for it as a
fact. Perhaps Stephen Hawking is correct when he suggests that the absence
of tourists from the future is the strongest argument against the
existence of time travel.
Of course, this doesn't imply that it is impossible. It may only mean that
it is never developed, or that it is developed but never used.
