4. Can we travel through Time?

Hello! Welcome to our new topic.. Time travel - One of my favorite and fascinating topics related to Time.

We have seen it in movies like  Back to the Future, Somewhere in Time, The Time Machine, The Butterfly Effect, etc. Ever since Einstein had explained Time Dilation in his Special Theory of Relativity in the early 19th century, the concept captured every one's attention and gave a hope and formed a curiosity in every one's mind about traveling through Time! 

Right now, we all know what Time travel is. If you are not sure, what I am talking about, then here is the explanation for you. Time travel is a hypothetical concept (so far) which states that it is possible for us to travel to the future as well as the past. For an instance, one can travel from 2010AD to 2150AD or 2010AD to 1750AD but the concept doesn't involve any proof or come up with any theory that says how it is possible!

In 1905, Einstein's Time Dilation theoretically proved the concept of Time Travel. I would say, At least it has an explanation that supports the possibility of Time travel. Still the explanation is partial. What I mean by partial is that Time Dilation proves only the travel to the Future and the traveling to the past is still a mystery! 

Let's see what Time Dilation tells about Time travel. In order to understand Time Dilation, let's explore a concept called 'Twin Paradox'. It goes as.. there were twin brothers and one of them was a space traveler. One day, he started his journey into space for a mission with a help of a space craft that can travel at the speed of Light (Technically it's not possible because any matter, from this universe, can't travel at the speed of Light but it's possible to create space craft which can travel at speed that is close to the speed of Light). 

Please refer the below diagram (diagram is from here) for better understanding.

As this diagram shows, space traveler starts his journey into space while the twin brother stays on earth. Let's say that the Time axis is in terms of years in this space-time graph. Though they started at the same time, as you see in the diagram, when the space traveler spent 6 years in travel and returns to the earth, the twin, who stayed on earth, would have already completed 10 years of life. These numbers are not exact results but the objective is to give you a clear understanding of the Time Dilation! 

Here you go, notice that the space traveler ultimately ended up traveling into the Future! But traveling to the past is still a question! So until we prove traveling to the past is also possible, Time travel remains a mystery, at least partially!