The 3 Schools of Time Travel Theories, Part 2: Fixed Timeline

Estimated reading time: 4 minutes

Last Saturday we started this series about time travel theories and the paradoxes that arise from each, with an introduction and a “quick” look at what paradoxes are, why and how they exist. Then, on Monday, we discussed the Dynamic Timeline theory and its biggest paradox, the Grandfather Paradox. Today we’re going to look at the second time travel theory, a possible solution for the paradoxes of the Dynamic Timeline: the Fixed Timeline.


The idea behind the Fixed Timeline theory is that time, the past and the future, is, as the name implies, fixed. It’s a deterministic view of time where we cannot ever change the past because the past has already happened, and that’s the only way it will ever happen… because that’s the way it happened.

This time travel theory has an abundance of closed loops, due to its deterministic nature. For example, contrary to the Dynamic Timeline theory, you would be unable to go back in time and kill Hitler because if you had, then we wouldn’t have had a Hitler to begin with.

In the Dynamic Timeline theory, you could have been able to go back in time and tell something to yourself that would have changed your whole future. But if you believe in a fixed timeline, then you wouldn’t be able to do this because, if you were, then past you would have already been visited by future you and told whatever he needed to be told.

This closed loop system also solves the Grandfather Paradox because you can’t go back and kill your grandfather. The reason? No time traveler from the future came back and killed your grandfather in the first place. So you might go back and attempt to kill your grandfather, but all you’d be doing is playing your part in an assassination attempt that your grandfather never told anyone about.

But this same closed loop system that solves the Grandfather Paradox, also introduces a new one.


The Causal Loop. In short, the closed loop nature of the Fixed Timeline theory can create situations where Event A causes Event B which causes Event A, leading to a chicken and egg situation with no clear beginning, and an unsolvable paradox.

Let’s figure out and explore a scenario where the causal loop could wreak havoc on our relatively fragile concept of time.

Imagine you’re a dude with a time machine, in a future where the time machine has become a common consumer product. One day you decide to travel back in time to visit the inventor of the time machine, Albert. So you grab a copy of the first ever time machine blueprints to be designed and published by Albert (because you want to get them signed), and head into the past.

You arrive at a time when Albert hasn’t yet even started working on time machines. After the initial confusion wears off, you discover that you’re the first time traveler to ever visit Albert (from his perspective).

You sit down and explain how his invention will change the world. Much to your surprise, your conversation inspires Albert to start working on the time machine.

So far this is a standard, Fixed Timeline story. You were the one who set in motion Albert’s interest in inventing a time machine. He never told anyone, but you know that there’s no way you can change anything in a Fixed Timeline world so this must be what originally happened.

Now comes the paradox.

As you’re about to leave back to your present, you remember you brought the Time Machine blueprints with you for Albert to sign… When Albert sees the blueprints, he asks for a copy and you happily oblige him.

After you leave, Albert, using the blueprints you gave him, designs and develops the time machine then proceeds to publish a copy of the blueprints you gave him.

All is well, right? Well… not really.

See, the blueprints you brought from the future were designed by Albert. The same blueprints you gave past Albert, which he later published in his own name. The only way he could have published them is if you gave them to him. And the only way you could have had them is if he published them.

Does your head hurt, yet?

And here we see the causal loop in full effect:

Who designed/published the blueprints, the first time around?

It’s a simple question that’s entirely impossible to answer with a Fixed Timeline mindset. It couldn’t have been Albert, because then you would have changed the past, and we can’t have that, can we?

Luckily for us, there’s a third and final theory, the Multiverse Theory, which solves both the Grandfather Paradox and the Causal Loop… but at what cost?

The 3 Schools of Time Travel Theories – Table of Contents

Part 0: Paradoxes
Part 1: Dynamic Timeline
Part 2: Fixed Timeline << YOU ARE HERE
Part 3: Multiverse

Amante Reale

I'm a freelance writer specializing in tech, gadgets, security, cryptography and cryptocurrency. Warning: I am armed with very strong opinions and I'm not afraid to use them. Hire me!