The mathematical model that says it is possible to go back to the past (and solves a problem faced by these theories)

Time travel may be theoretically possible, but a paradox can complicate it. A new study claims it solved that problem, at least in the world of math

Imagine that you have a time machine with which you can travel to the past.

At this time, you would have the possibility to travel at the end of 2019 and prevent the coronavirus pandemic from unleashing .

Your mission would be to find patient zero , just before he caught it and began to spread the virus.

Sounds good right? The problem is that a small detail would prevent you from completing that mission.

It is true that some interpretations of theoretical physics claim that time travel is possible.

Einstein , for example, was aware that his equations allowed, in principle, time travel.

That theoretical possibility, however, collides with what scientists call a “paradox” , which would make it logically impossible for the trip to take place.

Those paradoxes are a killjoy for time travel enthusiasts, but now new research claims they can be dodged.

What are these paradoxes and why does this new study claim that it is possible to avoid them in order to travel to the past?

A grandson who murders his grandfather

To understand what a paradox is, let’s go back to the history of the pandemic.

If you travel to the past and prevent patient zero from being infected, a paradox is immediately created.

That is, if you manage to stop the start of the pandemic, today we would not have a pandemic, therefore, you would have no reason to travel to the past, then you would not travel to the past and you could not prevent the pandemic from unleashing.

That’s the paradox, an infinite loop that creates logical inconsistency and destroys the illusion of time travel.

There are many paradoxes, but this is one of the most famous.

It is called the “grandfather paradox” because its original version poses a scenario in which a grandson travels to the past to kill his grandfather before he had his father.

The problem is that if he kills his grandfather, the traveler could never have been born.

If he cannot be born, he cannot travel, so time travel would not be possible either.

Dodge the paradox

To solve this paradox, several mental exercises have been proposed, but now, two researchers in Australia, propose a mathematical solution to avoid it.

The researchers wanted to analyze how the dynamics of a body, that is, its movement in space-time , behaves when entering a curve of travel to the past.

For this they created a mathematical model with which they calculated that an “agent” who enters a loop of travel to the past, can take different paths without altering the result of their actions.

His abstract exercise shows that several agents can communicate in the past and present, without a cause-and-effect relationship .

That means that “events adjust themselves, so that there will always be a single consistent solution “, Germain Tobar, a physics student at the University of Queensland and author of the study, who was supervised by Professor Fabio, tells BBC Mundo. Costa, philosopher and theoretical physicist.

And what does this mean?

Returning to the example of the pandemic, what the study says is that if you travel to the past you could do whatever you wanted , but it would be impossible for you to change the outcome of the events.

That is, you would have free will, but you could not prevent the pandemic from unleashing.

It could happen, for example, that while you are trying to stop patient zero, it is someone else who becomes infected, or even yourself.

According to Tobar’s model, the most relevant events would be constantly calibrated to avoid any inconsistency (paradox) and thus always reach the same result, in this case, the start of the pandemic.

Understand the universe

Tobar’s study is applicable only in an abstract way in the field of mathematics.

“It’s an interesting job,” Chris Fewster, a mathematics professor at York University, who studies time travel models, tells BBC Mundo.

Fewster, however, warns that now “it remains to be seen whether the abstract conditions that (the authors) have imposed are met within the currently known theories of physics.”

Tobar says that is precisely the challenge they have now: testing their model on a physics setting.

For now, although his work is far from making time travel a reality, Tobar says it is progress in better understanding the laws that govern the universe.