"Time Travel Theory"

Donnie : Where did you come from?
Frank : Do you believe in time travel?

(Frank is the <spoiler>time-travelling ghost rabbit</spoiler> from Donnie Darko.)

So, do you believe in time travel? Of course, everyone time travels--as you're reading this, the seconds are passing by and you're travelling forward in time. But obviously, that's not the kind of time travel I'm talking about here.

The possibility of visiting the future, and/or changing the past has always fascinated humankind. Time travel is a popular recurring theme in books, TV shows, movies and even games. Great philosophers such as Cher and Lene Nystrøm have wondered aloud what they would do if they could "turn back time".

Is time travel really possible? The answer (of course) is "it depends". :)

For a possible explanation of how time travel might work, one has to go deep into the nature of "time", and that of the universe itself. While an in-depth discussion is beyond the scope of this post, a brief description follows.

We all know the three dimensions--length, breadth and depth, but it is hypothesized that there are at least 10 dimensions (some say 11, some say 26...). It is tough to explain this because the concept is almost impossible to visualize with the capacity and capability of the human brain.

Now think of time as just another dimension. “Time travel” thus just becomes a linear journey along a single dimension. Imagine you are climbing a ladder or walking along a road. As you climb higher (or walk further) you can see things that you couldn't see before. If you climb down the ladder (or walk back), you can again see the things you were seeing before. Now suddenly, time travel doesn't look all that far fetched--you move forward in time and see things that are going to happen; you move backward in time and see things that have already happened. (Of course, this is an overly simplistic view and ignores a lot of variables, but I think is sufficient to get the point across.) This linear movement in the 'time' dimension can be called a 'timeline'.

So far so good. Now, let's complicate this further. Suppose, at every instant in time (here an ‘instant’ is unfathomably small), the "main" timeline splits into infinite other timelines, where each timeline varies from the other by the tiniest amount possible. Every single event that can occur at an instant, and all combinations of other events that can occur simultaneously, are covered by one unique timeline. Now we designate one of these simultaneous timelines as the "primary timeline".

Thus at every instant there exists one primary timeline, and infinite “tangential timelines”, which are nothing but timelines where the infinite other possibilities (which didn't happen in the primary timeline) happen.

Still with me? Great! To understand the next part, one must first know an important characteristic of a hologram -- every part of a hologram contains all the information possessed by the whole. So, if you split a hologram, you will end up not with two halves, but in fact with the equivalent of two (but smaller) wholes.

So now, how about we view the “universe” as one gigantic n-dimensional, extremely detailed, super-hologram, where all possible timelines exist simultaneously? This would mean that every smallest ‘part’ of the universe contains ALL the information in the universe. What does this imply? For one, you and I are part of the universe and hence we would contain within ourselves all the information in the universe--past, present, and future!.

Clearly, then, you already know everything that has happened, and everything that will happen. You just don't know which one is going to be the 'primary' timeline at a given instant of time.

(This of course leads to a lot more questions, the answers to which are beyond the scope of this discussion. For example, what determines which timeline becomes the primary? Is there a single primary timeline for the whole universe or does each entity in the universe have its own primary timeline from its point of view?)

The primary timeline at any instant is what is perceived to be the "present". However, under certain circumstances it is possible to access information in other timelines (these timelines may or may not be at the same 'instant' in time) and this inter-timeline information exchange is what leads to phenomena like 'premonitions' and 'deja vu'.

Once "the present" is defined so, "time travel", including changing the past and peering into the future, becomes a matter of simply(?) choosing the right timeline!

See how simple that was? And if I'm right, you knew this all along!

(P.S: Does some of the content of this post sound familiar? Then you also know why!)

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