TIME TRAVEL

TIME TRAVEL
Time Travel is has been a long thought concept and a one of the most interesting unsolved mystery of physics.Time and now various theories have came but none could  
establish any thing concretely.Stephen hawking is one of the many working on this.Time travel to the past is something that has created many paradox like the Grand father Paradox,shown below is it's simpler version calledmad scientist Paradox.   

WHAT'S TIME TRAVEL

Time travel is the concept of moving between different points in time in a manner analogous to moving between different points inspace, either sending objects (or in some cases just information) backwards in time to some moment before the present, or sending objects forward from the present to the future without the need to experience the intervening period (at least not at the normal rate).

Although time travel has been a common plot device in fiction since the 19th century, and one-way travel into the future is arguably possible given the phenomenon of time dilation based on velocity in the theory of special relativity (exemplified by the twin paradox), as well as gravitational time dilation in the theory of general relativity, it is currently unknown whether the laws of physics would allow backwards time travel.

Any technological device, whether fictional or hypothetical, that is used to achieve time travel is commonly known as a time machine.

Some interpretations of time travel also suggest that an attempt to travel backwards in time might take one to a parallel universe whose history would begin to diverge from the traveler's original history after the moment the traveler arrived in the past

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.3 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.4 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.