Time travel is a very interesting subject that has attracted the attention of not only the great minds (scientists) of the world, but many other people (referred as common man) especially the younger ones often get fascinated by the idea of time travel. However those who have tried to study the time travel a little must have come across the paradox associated with the time travel. One such paradox is the "Grandfather Paradox"
Simply stated, "Grandfather paradox" puts forward a hypothetical situation that if one travels back in time and kill their grandfather before he conceives one of their parents, which precludes their own conception and, therefore, they couldn't go back in time and kill their grandfather.
Now, as a layman and thinking about it, I have developed a query on the same. To understand that, lets consider a example where a rat has travelled in a two dimensional floor from point A to point B. In doing so, the rat has travelled through several walls that had one way doors to let him travel from point A to point B but not the other way round (point B to point A). The rat is now trapped at point B as it doesn't know that there is another way (Z axis) through which it can travel back. It keeps moving ahead and the path follows a third dimension which takes him vertically and the rat follows a path exactly backwards towards the point A and reaches a point C that is vertically above point A. Now, the rat which understands only two dimensions, feels that he is home at point A and tries to find his home (hole in the earth), but can't find it. Why? Because he is not exactly at the same point. He is in a different dimension. Some scientists may take is as a parallel universe in view of time travel, but for me it is not.
Coming back to the original equation, when a person travels back in time, he is still bound by the dimension of his own time. He is still ageing in the same forward direction as he was before the start of his time travel. So, when he reaches the point where he sees his past, he is actually seeing just a reflection of the past and is not actually at the exact coordinate because he is still bound by his own time dimension. Confusing, isn't it? Yes, but the question is that to be able to change the history, person who has to be at the exact coordinates where that event happened in the past and these coordinates include not only space coordinates but also time coordinates .
We all might have heard of 3 dimensions and we can locate an object in space by assigning three coordinates to that position. Lets assign position of any object as (X,Y,Z). Now lets add time dimension to his position and define his position as (X,Y,Z,T).
Now, in the grandfather paradox, lets make a small change and assume that the person wants to kill himself at a much younger age. Lets call those coordinates of his younger self as (X1, Y1, Z1, T1) & present self as X2, Y2, Z2, T2). Now when he wants to travel back in time, he has to leave the plane of his present time dimension. But as soon as he will leave that plane, he is no longer bound by his original time dimension. But all his memories are bound by that time dimension in which he has travelled through his life. So, those memories may not hold good when he leaves his original time dimension which means he will not have any purpose of travelling back in time and will be blank on reaching in the past time. So, he won't remember that he had travelled back in time to kill his past self. And hence, he may not be altering any reality.
However in my opinion, leaving the time dimension to reach that exact time & location where the original incident happened, may not be possible. We all are bound by time which always travels forward and unless we find a way to reverse the time itself, we are likely to be travelling to the past as a meager spectator from a different time axis. We can't change anything and there will be no parallel universe either.
And if we can find a way to reverse the time itself then by the time we reach that past point, the world itself had went to the past. So, it will mean the future itself has never happened and whatever happened has become a clean sheet of paper again. There won't be existence of any future self. Only the past self will be there and hence again, no alterations to the past will happen.
