Time

Time?

Time travel is no longer regarded as strictly science fiction. For years the concept of time travel has been the topic of science fiction novels and movies, and has been pondered by great scientists throughout history. Einstein's theories of general and special relativity can be used to actually prove that time travel is possible. Government research experiments have yielded experimental data that conclusively illustrate that fast moving aircraft have traveled into the future. This phenomenon is due to the principal of time dilation, which states that bodies moving at high velocities experience a time that ticks slower than the time measured at zero velocity. Not as much time elapses for a moving body as does for everything else. Phenomena known as wormholes and closed time like curves are possible means of time travel into the future and the past. Traveling into the past is a task which is much more difficult than traveling into the future. This feat has not yet been accomplished -to our knowledge- and its theory involves complicated scenarios of tears in four dimensional space-time, and traveling near the speed of light. Obstacles which prevent our hubris attempts to cheat time include our inability to move even close to the speed of light, and finding a source of energy as powerful as an exploding star. Simply because the proposal of time travel is backed by scientific theory, is no reason to expect that it is easily achievable. Numerous arguments are proposed that that prevent time travel into the past. Both common sense and scientific fact can be used to paint scenarios that become serious obstacles. Not to fear, we have all the time in the world to overcome these minor limitations.

Imagine if you will, that you are one of the people sill alive today that was born prior to 1903, when the first airplane took flight. When you were young the idea of flying would probably have been quite exciting. Some scientists believe that we may presently be living through an identical scenario. The thing that would be so exciting however, would not be flight, but time travel. Leading scientists believe that our children will live to once again see the impossible become routine. Professor Michio Kaku of the University of New York believes that space flight may one day unlock the secret of time itself. This will require the development of spacecraft that can travel at speeds on the order of two hundred million meters per second, that's about four hundred and fifty million miles per hour. Craft traveling at this speed will take us near the speed of light, where time actually slows down. This is what's known as time dilation. Einstein's theories predict that the faster a spacecraft moves, the slower time ticks inside of it. Imagine that a rocket ship takes off from earth and approaches the speed of light. If we were to watch it from earth with a very powerful telescope as it traveled away from us, we would see everyone inside the ship as being frozen in time. To us their time would slow down, but to them nothing would change! This has been measured in the laboratory and on location using atomic clocks, aircraft, satellites and rockets. It is proven that time slows down the faster you move. In 1975 Professor Carol Allie of the University of Maryland tested Einstein's theory using two synchronized atomic clocks. One clock was loaded on a plane and flown for several hours, while the other clock remained on the ground at the air base. Upon return, the clock on board the plane was found to be ever so slightly slower that the one on the ground. This was not due to experimental error, and has been repeated numerous times with the same result. This difference in time is even more pronounced in satellites such as the space station. This is because these objects are traveling at speeds much faster and for much longer periods than possible in an airplane. The faster an object moves, the more time is distorted.

Now that we know that it is possible to travel into the future by moving at great speeds, the next problem is how to travel in time a respectable amount without having to sit in a fast moving spaceship for years. This problem is solved by the theoretical existence of what are know as closed time like curves, and wormholes.

Einstein's special and general theories of relativity combine three-dimensional space with time to form four dimensional space-time. Space-time consists of points or events that represent a particular place at a particular time. Your entire life thus forms a sort of twisting, turning worm in space time! The tip of the worm's tail would be your birth and its head is the event of your death. The line which this worm creates with its body is called that object's world line. Einstein predicts that world lines can be distorted by massive bodies such as black holes. This is essentially the origin of gravity, remember. Now if an object's world line were to be distorted so much as to form a loop that connected with a point on itself that represented an earlier place and time, it would create a corridor to the past! Picture a loop to loop track that smashes into itself as it comes back around. This closed loop is called a closed time like curve. Time like means that the body under consideration experiences time that increases in one direction along its worldline. Princeton University physicist John A. Wheeler, and Kip S. Thorne of Cal. Tech. have shown that a closed time like curve is one way to create a kind of shortcut through space-time called a wormhole.

Wormholes are holes in the fabric of four dimensional space-time, that are connected, but which originate at different points in space and at different times. They provide a quick path between two different locations in space and time. This is the four dimensional equivalent of pinching two pieces of a folded sheet of paper together to make contact across the gap. Distortions in space cause the points separated by the gap to bulge out and connect. This forms a wormhole through which something could instantaneously travel to a far away place and time. No more problems of traveling in a rocket ship for years to get into the future! This is essentially what was written about in "Alice in Wonderland's Through the Looking Glass." Her looking glass was a wormhole that connected her home in Oxford, with wonderland. All she had to do was climb into her looking glass and she would emerge on the other side of forever. In reality however, it would require a much more elaborate scheme to create a wormhole that connects two different points in space-time. First it would require the construction of two identical machines consisting of two huge parallel metal plates that are electrically charged with unbelievable amounts of energy. When the machines are placed in proximity of each other, the enormous