Einstein's theories demand that one needs to travel at the speed of light to go to the future and more than the speed of light to go to the past. Then the question is 'travel to where'? So far the answer is through space. So, in order to go to the future even before it happens at the Time's own pace on earth, we need to travel through space at the speed of light. Having said that do you see that it is conflicting the 4th characteristic of a dimension!? If Time is a true dimension , then moving in time's direction should not require or impact the position of an object in it's 3 dimensional space.
This is the first stop sign for us to give a second thought when we are talking about Time Travel. What Einstein was referring to was not 'Absolute time' but 'Relative time'. Why is it relative? Simple because he was comparing two clocks! As we saw in our previous posts, he is comparing the one on earth with the one on the space craft. Moreover, he was the one who gave us the definition of time as 'Time is nothing but what is shown or measured in a clock'!
Let's go with the concept of relative time. As pointed out by J. Richard Gott in his book 'Time Travel in Einstein's Universe', the Russian cosmonaut Sergei Avdeyev traveled over the speed of 17000 miles/hour on a space craft for, so far, the longest period of 748 days. When he returned to the earth, he was 1/50th second traveled into the future. In other words, his clock was running 50 secs slower than the clock on earth!
This is the second stop sign to give a second though before we claim that he has traveled into his future! Did he really travel into his future? Before answering, we need to clarify a point here! As long as we are talking about relative time, we cannot just talk about future because it's out of the context of the person who travels through space. What we are talking about is nothing but 'Relative Future'! Yes, because it's not the same future what the astronaut would have encountered if he stayed on earth! Let's say for example, if he stayed on earth, he might have got married during that period. The fact is that once he leaves the earth, Since he was not part of the present on earth, when he will return to the earth he will not be part of his future but his relative future.
Even if we consider the concept of relative future. There are few incomplete or illogical claims. What is the truth? Did he remain really younger in terms of his age and real life? Or did his clock on the space craft just slow down and give the illusion, like how a clock slows down when its battery goes down?! To answer this, astronaut has to travel at higher speeds for longer period because it'll be accurate only when the time dilation or difference is in terms of years not hours or days.
Proving the 'Time dilation' does not actually prove the 'Time travel' because of the following problems with this approach.
1. The future, which Astronaut sees, is not necessarily the same as what he might have seen if he would have stayed on the earth.
2. He didn't travel through the series of incidents that might have happened in his life on earth rather he skipped all of those incidents and ended up in a future which is out of his context!
3. He cannot go back to either his past or relative past, if any because he cannot change what happened on earth.
Here is how I conclude my hypothesis on Time:
1. Though 'Time' can be used as an attribute to refer a position of an object, it is NOT a true dimension as it doesn't satisfy all the characteristics of a dimension.
2. One cannot see his future using Time Travel because as soon as he leaves the earth he is absent on earth. Hence what he will be seeing is the future of the earth without his presence.
3. According to quantum theory, the river of time forks into two separate rivers. By going back in time and altering the past, we are traveling into someone else's past in some other universe where we don't belong to by saving, for example, Abraham Lincoln from being assassinated at the Ford Theater, but our Lincoln is still dead in our universe.
4. There is no theory, so far, that has assured or formed to confirm that there will definitely be Abraham Lincoln in the parallel universe, just like the one in our universe! It is just the hypothetical understanding that when we say parallel universe, it's taken for granted as a duplicate of the other. It may or may not be true! Because of the enormous amount of work done by theoretical physicists within the last five years or so, Hawking has since changed his mind, and now believes that time travel is possible (although not necessarily practical). It's not possible to travel to the Past as Time always travels in one direction unless Time has parallel tracks running around the black holes as a whirl pool.
Finally, what has been proved as Time Travel, so far, is nothing but traveling into one's 'Relative future' where the traveler can't see his own future but the relative future of the earth, simply Einstein's 'Time dilation'. The truth is that Time is the only way of preventing everything from happening all at once and allowing to happen only once!
