The Grandfather Paradox Solved: Is Time Travel possible?

Is time travel possible? Can one be dead and alive at the same time? Is it really possible to live in a parallel universe? What’s The Grandfather Paradox and what is its solution? Well you will get all those answers today in this blog. Read it till the end.

Don’t leave it the mid-way. I promise you will regret, because today you are going to get something really interesting and mind blowing.

Suppose you have somehow managed to get a time machine and you travel back in past. And you accidentally or knowingly – that doesn’t matter – kill your grandfather before they have kids. That would mean your mother was never born – and you are also never born. But then who kills your grandfather? So killing any ancestor in the past affects the whole chain of future events. Well, this is a paradox what we actually know as ‘The Grandfather Paradox’.

As a matter of fact this paradox first came into existence in the 1920s or 1930s – while it gained it name ‘The Grandfather Paradox’ only in the 1950s.

Now you necessarily don’t have to kill your grandfather – you can do anything that would affect the future chain of events. Now, the question that comes here is – Is it even possible to travel back in time?

Well, the late and great scientist Stephen Hawkins said in one of his lecture on ‘space and time wraps’ that Einstein’s theory of relativity might make it possible to travel back in time. The theoretical possibility of this time travel is that the wormhole loop back on itself. Wormhole is basically described as shortcuts between two points in the space. If this wormhole loops back on itself to an earlier point of time, it might be possible.

But even if it’s possible wouldn’t be the Grandfather paradox a trouble? Of course, that would be. So if you don’t want to be trapped in this trouble anymore, let’s come to the solution of this brain-twisting, mind-boggling paradox.

But hang on. Before we come to the solution let’s play a game – that will actually help you to grasp the concept of what you are going to learn.

Well consider a strip of paper. Now if an ant starts walking from a given side and wants to reach the other side, it evidently has to cross the first side first. But can you make a 2-D manifold such that it has only one side? Quite confusing, huh?

Take a strip of paper and join one edge to the opposite edge. But before joining them give the strip a half twist and connect them. This will be a one-sided strip called – Möbius strip. 

Möbius strip

To check whether it is one sided or not, start making a line on anywhere of the paper with a pen and you will eventually reach the starting print without crossing any side.

Now what’s the relation between this Möbius strip and the grandfather paradox?

Well, let’s see. We represent the timeline by the surface of the Möbius strip. Now if you write the below sequence on the strip you will get a loop. It will be better if you do this practically.

You are born » You travel back in time » You kill your grandfather » Your mother is not born » You are not born » You don’t travel back in time » You don’t kill your grandfather » You are born

Image source: Geeks out of the box

Now you are stuck in the loop. And if you wrote it down on the strip continuously, you will get to the point where you started on the paper. And to your surprise you will see that ‘You are born’ and ‘You are not born’ are written at the same point on opposite surfaces. Similarly other contradictory phrases will also be found on the opposite surfaces. Now as we have taken the surface of the strip as timeline, this means that at the same time you are born and you are not born. At the same time you kill your grandfather and you don’t.

But, but, but – how’s that even possible? How can you be both dead and alive at the same point of time?

Well, that’s where we get the concept of parallel universe or parallel timeline.

So according to this theory – when you travel back in time, you are not actually making changes to your own history. But you are landing on another parallel timeline. That’s because an exact copy of something doesn’t exist anywhere in the universe. So it basically means that in that parallel universe your grandfather is dead, so obviously you would not be born either in that timeline.

Now physicist David Deutsch showed that parallel timelines cannot overlap, but it is possible only under the presence of closed time-like curve (CTC), when a wormhole curves back on itself as I have talked about earlier. [If you want to study the topic CTC or Wormhole you can study Wormhole on Britannica, Wikipedia, Livescience. ] But that’s the question – can two timelines overlap? Well, it will be better to leave that question to the scientists, as of course I don’t know that. (Ask any scientist may be he knows) But what I can tell you is that subatomic particles do this thing – and it’s called quantum superposition.

Now to get an idea about superposition you can imagine throwing two stones in a pond. The stones will create two waves and if they overlap with each other, it forms a complex pattern. This is the superposition of water waves. 

Superposition of water waves

Now if you look this from the electron point of view (you must know that electron are also waves) – quantum waves are mathematical unlike that of water. These equations provide information about the probability of the position of an electron or its speed. And on that basis, we define its properties. But when an electron is in superposition, it might be said to have two different velocities or two different positions at a time. Well, you must know that this superposition is actually responsible not only the properties of atoms and molecules, but also fusion and fission in the sun and many more.

If this superposition or the closed time-like curves or overlapping of parallel timeline – whatever you call it – is possible, then you would be able to stay alive even after killing your grandfather – and that also in a parallel universe. So you have got the solution in your hand. This might be a bit difficult to get, so you may need to read it twice or thrice. 

So that's all from the Grandfather Paradox