Time travel is the concept of traveling through time, either to the past or to the future. Several aspects of the Theory of Relativity suggest that such travel is possible. For example, an object that passes through a black hole will then enters an Einstein-Rosen bridge, or "wormhole." The properties of a wormhole or not restricted; It may lead to any time or place. The theory also implies that an object that travels faster than light travels backward in time. These predictions have not been verified experimentally. If they ever were, they would lead to contradictions and paradoxes. The fact that relativity allows this possibility can be viewed as a flaw in the theory.
There is a scientist named Ronald Mallett who is trying to develop a real time machine. A form of time travel into the future is possible - if one were to travel close to the speed of light, one would age much slower than anything stationary, so it would seems as if one had time traveled to the future. In fact, this effect happens at any speed - when we drive a car, or even walk, we age ever so slightly slower than if we were stationary, however, this effect is so miniscule as to be unnoticeable in our day-to-day lives (although scientists have conducted an experiment where atomic clocks on the ground were compared to atomic clocks that had been on a plane, and found time dilation had caused a 273 nanosecond discrepancy, meaning the effect is detectable with specialised equipment).
Time travel has captured the imagination of many authors and filmmakers, particularly in the 20th century. In early science fiction novels, time travel was used to promote political ideas of utopia, mainly socialism. For instance, The Time Machine, the first novel to use this concept, is intended as a criticism of the class system. Edward Bellamy's novel Looking Backwards, written in 1887, centers around a contemporary man who goes into a hypnotic sleep and awakens 113 years later in the year 2000, by which time America has turned into a socialist utopia. However, the decreased popularity of socialism has contributed to the decline of this genre. While politically motivated science fiction still exists to a lesser extent, the vast majority of it is simply set in the future and does not involve time travel as a plot device.
- http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html Hafele-Keating Experiment