But i believe that this act will not affect his identity,and even his grandfather or father of his time..
How??
Now, let’s take an analogous example..
We know that it takes 8 minutes for a light from sun to reach the earth. And if somehow the sun vanishes, then the earth will still revolve around the expected point for 8 minutes.?
Now let’s go to the main core..
Assume that there’s a star of mass infinite kg, and there’s a planet which is infinite km far from that star.
Now this delicate physics, will cause the planet to revolve around that star, as it happens with our earth.
Neglect the reason that how that gravity reached the planet covering the infinite distance..
Now same,assume that the star vanishes.. Now what will happen.. Light takes infinite time to reach the planet i.e. the light can never reach there.. So, the planet will revolve forever as if the star is still there…
Take an another example,
Suppose there’s a huge building.. And we destroy the just first floor of the building.. As the the first floor is the foundation of the above floor, the whole building will collapse. But if we measure the time interval between destruction of first floor and departure of the above floors using atomic clock then we’ll find that it’s not zero indeed.. For a fraction of time, the above floors were perfect even though the foundation was destroyed.
Ultimately it means that the reaction of an action is not instantaneous. There’s no immediate effect of any action,i.e if there’s any action, the reaction will come after sometime,and not instantaneously..
Now back to main point, time also travels a speed ‘v’ through the timeline.. So when a timetraveler from 2010 changes an event in past 1940, the effect will also travel at the same speed of time i.e ‘v’. So it will never catch up the actual time(2010) of the timetraveler.(as car traveling at a speed of 90kmph can’t catch the another car who is traveling at the same speed of 90kmph)So the effect in 1990 will never affect the universe in 2010 even though the foundation is changed (obviously,1990 is the foundation of 2010).. It happens because time taken between action and reaction is infinite.. Here ,the 2010 will be protected, and all, he, his father and grandfather will be alive even though they are dead in 1990.. 2010 will be changed after 20 years, i.e at 2030 for the timetraveler.. So At any case the timetraveler is fully protected from the mutation of his past..
Means.. It’s possible to go to the past and change it but it won’t be of any use, as it will not affect our present time..