Science fiction is what you would have thought when you read the title of this section, if so don’t be upset - no science fiction, I just want to put together few strings and show you that this is no science fiction – unless you really want a time machine to travel back / front in time.
So how is that even possible? Lets get some basics first - time lost is lost. You neither me nor the greatest minds in the world can get it back. So time is irreversible, ok let keep that aside and see if we can come to a conclusion about travelling to future. Can you skip today and go to tomorrow directly. It can happen unless you want to come back to today. So you can just take a sleeping pill and sleep the whole day and you will be in tomorrow directly. That is possible by some means but still you will age as usual. Again going to future (unless you do space travel) is not possible. Even that's relative.
So for you and me, as of now time travel is not possible. Can we say that? And it would be an absolute truth and no one would argue. May be I will be able to raise a doubt about that in the next few minutes. The true measure of time is relative, as 1 hr for me and 1 hr for a person in middle of Sahara desert is not the same. It may be in measurement same but relatively different, let’s take an example - you want to travel from point A to point B and the distance is 500 Km, the speed at which i travel determines the time at which i can reach my destination. Another wonderful thing about time – most of the derivation cannot be solved without time as a parameter. So I travel at 50 km/h speed and reached point B in 10 hrs or 11 hrs. Same way, let’s say if I walked all the way and may reach is 2 - 3 days depending on how fit I am. Look at the time difference. I may have saved more than 24 hrs, what I do with that time is different but I have traveled forward in time. I have reached to point ‘B’ today which I am supposed to reach after 2 days. By the time I walk to point ‘B’ I would have finished my work and returned back to point ‘A’. How can it not be time travel in the real sense of life. That's not it there is one more angle to it. Let say one human travels in total of 100000 km in his/her life time. Approximately he/she would have saved close to 1 year (more than 365 days). So dose it mean that that person will live for 1 more year (or) he/she would loose 1 more year. The person who walked all the 100000 KM has lived longer as time is relative he would experience things that a person travelling by a automobile cannot, because we just pressed a forward button and skipped every thing (or most of it) between point A & B. So the relative time is much faster, if you believe life is what we experience then this is as true as it is. You may think if I travel faster I could go many places and the life’s experience would be the same in numbers as the person who walked all the way. That's where its relative walking all the way certainly feels longer than other means.
But again even the time travel that we do is relative, because we are so use to this fast means of transport, we just do not acknowledge the length of time unless we run a marathon. That's where a person in 60’s and 20’s differ, a man in 60’s would have traveled a lot that a man at 20’s, but may be the man at 20’s travel the same distance as the man in 60’s. But their experience with time is different. More like saying I know alphabets starts from A to Z and saying I know all alphabets starting from A to Z.
--------- Happy travelling ---------