Exploring time-travel paradoxes

You can either read the article below or watch the corresponding YouTube-video above!

What is time? Can time pass? Do we pass through time? Is time a real property of the universe, or perhaps an illusion only existing in our mind?

What do we mean with past, present and future? Does the future somehow exist already without us being able to detect it yet?

But something that we do more often is to think about the past and ask the question “What if … ?”

What if I would have bought that other house?

What if I hadn’t lost my control that day?

What if the 9/11 terrorists had been stopped by security guards at the airport?

This is called counterfactual thinking.

Thoughts like these are usually triggered by negative events that block one’s goals and/or desires, and someone therefore focuses on how the past or the present might have been different when certain things would have been done, said or prevented.

Whenever we say “if only” or “almost”, or use words like “could”, “would”, or “should” we may be expressing a counterfactual thought.

And speaking of time, the concept of counterfactual thinking is perhaps the main reason many of us are intrigued by stories about time-travel, being able to change the past, or perhaps finding out facts that would be useful in the present.

Often time-travel stories center around a particular aspect of time-travel, the possible consequences of a traveler in time changing past events, which result in a nightmarish scenario playing out upon their return to the future, interestingly also impacting their ability to have traveled back to the past in the first place.

When you search for these interesting concepts, you quickly come across some fascinating paradoxes.

1. The Grandfather Paradox

This is probably the most famous paradox. It lays out a hypothetical situation in which a time-traveler goes back into the past to the time at which his grandfather didn’t have any children yet. The time-traveler than takes part in an event that ends up killing his grandfather, intended or not.

But when you think about it for a second, this means the grandfather could not have gotten a son or a daughter, and the time-traveler himself would not have been born either. Making the journey to his grandfather an impossibility. And thus, the grandfather would not be killed, would get a child, and years later the time-traveler would be born. Years before he will go back in time…?

Potential Solutions

There are suggestions on how to solve this paradox, for instance: that it’s somehow impossible to kill the grandfather, and that no matter what the time traveler tries or does, his mere existence is proof that his grandfather didn’t die before getting a son. Stories will sometimes use this concept to make clear to the protagonist, that the person who was told to be his grandfather, wasn’t his grandfather in the first place…

Another proposed solution is the principle of different time-lines. When the time-traveler would go back in time and cause his grandfather to die, he would actually have gone to another timeline, another world you might say, and killing his grandfather in a different time-line would not have any impact on his own existence, since the grandfather in his own timeline or world, was not killed before getting a son.

2. Bootstrap Paradox (Einstein)

The following scenario includes a time traveler who goes back in time and teaches Einstein the theory of relativity, before returning to his own time. Einstein then claims it’s his own work, and over the following decades the theory is published countless times until a copy of it eventually ends up in the hands of the original time traveler who then takes it back to Einstein, begging the question: “where did the theory originate?”

We cannot say that it came from the time traveler as he learned it from Einstein. We also cannot say that it is from Einstein, since he was taught it by the time traveler. Who, then, discovered the theory of relativity?

In paradoxes like these, there is a certain thing that seems to be in an impossible loop, that’s why it’s called Bootstrap paradox, in which bootstrap refers to “pull oneself over a fence by one’s bootstraps”, which, I hope you can imagine, is an impossible task.

There are in fact many such paradoxes out there. Most often a piece of information or an object is trapped in an infinite cause-effect loop in which the item no longer has a discernible point of origin, and is said to be “uncaused” or “self-created”.

Yet, there is one very interesting bootstrap paradox that includes a person (see below, part 3)!

 3. Jane’s family tree

A baby girl is mysteriously dropped off at an orphanage in Cleveland in 1945. Her name is “Jane”. Jane grows up lonely and dejected, not knowing who her parents are, until one day in 1963 she is strangely attracted to a drifter. She falls in love with him. But just when things are finally looking up for Jane, a series of disasters strike. First, she becomes pregnant by the drifter, who then disappears. Second, during the complicated delivery, doctors find that Jane has both sets of sex organs, and to save her life, they are forced to surgically convert “Jane”, who had always identified as a woman, to a “him.” As if that had not been enough, a mysterious stranger kidnaps her baby from the delivery room.

After these disasters, Jane, who is now called Jim, feels rejected by society, and becomes a drunkard and drifter. Not only has Jim lost his parents and lover, but he has lost his only child as well. Years later, in 1970, he stumbles into a lonely bar, and spills out his pathetic story to an elderly bartender. The sympathetic bartender offers the drifter the chance to avenge the father of the child, the stranger who had mysteriously abandoned them, on the condition that he join the “time travelers corps.” Both of them enter a time machine, and the bartender drops off the drifter in 1963. The drifter is strangely attracted to a young orphan woman, they fall in love and sooner or later the woman becomes pregnant.

The bartender then goes forward 9 months, kidnaps the baby girl from the hospital, and drops off the baby in an orphanage back in 1945. Then the bartender drops off the thoroughly confused drifter in 1985, to enlist in the time travelers corps. The drifter eventually gets his life together, becomes a respected and elderly member of the time travelers corps, and then disguises himself as a bartender and has his most difficult mission: a date with destiny, meeting a certain drifter at a specific bar in 1970.

So the question now is: Who is Jane’s mother, father, grandfather, grandmother, son, daughter, granddaughter, and grandson?

If we were to draw Jane’s family tree, we find that all the branches are curled inward back on themselves, as in a circle. We come to the weird conclusion that she is an entire family tree unto herself.

If time travel is at all possible, then it stands to reason that time machines will become cheaper, smaller, and more available, as they are further developed. Some suggest that at some point in the future, they will be so small, cheap and widespread, that everyone will have one, or have easy access to one.

If humanity survives to this point, it would stand to reason that people, being what they are, will become time tourists, visiting the various epochs just for fun.

As time travel will pretty much ensure that no disaster could wipe out humanity, even the ultimate death of the universe would not be able to end humanity, as humanity could simply go to safer earlier times.

Thus after the advent of the invention of time machines, there will be many of us humans, with increasing access to smaller and cheaper time machines. With a seemingly infinite number of time tourists thus able to visit pretty much any point in time and space they wish to. And it stands to reason that almost everyone, even right now, is in fact a time traveller.

So next time you are in a crowd, consider this:

You are likely one of the few around who does not have a time machine.