# Is it possible to travel through time in terms of mathematics?

There is hardly a person on Earth today who has never once thought about time travel. In many ways this is the merit of a popular culture – since its inception, the concept of time travel has entered the culture and influenced our perception of time.

As he writes in his book “Time travel. History” by the American writer, historian of science James Glick, the very concept of such travel – a little over a hundred years. So, if we believe the “Oxford Dictionary of English”, the term “time travel” first appeared in the English language in 1914 – inverse word formation from Welsh “Time Traveler” (so the fiction writer Gerber Wells calls the protagonist of his novel “Time Machine” (1895)). It turns out that, in some incredible way, most of the history of mankind lived without wondering what it would be if they went into the past or the future.

Now, physicists at the University of Cleveland have solved the age-old paradox, proving that time travel is theoretically possible from a mathematical point of view.

## The paradox of grandfather

In a study published in the journal Classical and Quantum Gravity, physicists at the University of Queensland used mathematical modelling to align Einstein’s General Theory of Relativity (GTR) with classical dynamics. Einstein’s theory allows the possibility that a person, using a time loop, goes back in time to kill his grandfather. However, classical dynamics dictates that the sequence of events following the death of his grandfather will end with the fact that the time traveler ceases to exist.

British The Independent quotes Germaine Tobar and Fabio Costa as saying that for many years they have been puzzling over how classical dynamics can match Einstein’s predictions. Their reflections eventually led to the creation of a mathematical model designed to determine whether the two theories could coexist. The model was based, oddly enough, on the coronavirus pandemic.

Let’s say that you traveled through time trying to stop a zero Covid-19 patient from getting infected with the virus. However, if you stop this person from getting infected, it will eliminate the motivation for you to go back and stop the pandemic. This paradox is an inconsistency that often makes people think that time travel cannot take place in our universe. Logically, this is difficult to accept, because it would affect our freedom to do any arbitrary actions. This would mean that you can travel through time, but you cannot do anything that would cause the paradox.

*Fabio Costa (left) and Germaine Tobar (right).*

Despite the fact that mathematics itself is complex, it comes down to something quite simple. The discussion of time travel focuses on closed curves, similar to the time that Albert Einstein first suggested. Both Tobar and Costa believe that as long as only two parts of the entire Special Theory of Relativity (STO) scenario are still in “causal order,” the rest is subject to free will.

In the coronavirus patient zero example, you can try to stop the infection of patient zero, but you will catch the virus and become patient zero yourself or it will be someone else. Whatever you do, the main events will simply regroup around you. This will mean that no matter what you do, a pandemic will happen, giving your young self the motivation to come back and stop it.

No matter how you try to create a paradox, the events will always adapt to each other to avoid any inconsistency. A number of mathematical processes that researchers have discovered show that time travel with free will is logically possible in our universe without any paradox.

*High precision time machine today is only in films and mathematical calculations.*

Although it sounds disappointing to someone trying to prevent a pandemic or kill Hitler, it helps mathematicians understand how we think about time. One way or another, new research suggests that anyone who eventually develops a way to meaningfully travel through time can do so and experiment without a hidden fear of destroying the world – at least not immediately.

## Amazing physics

The new discovery is also remarkable in that it smoothes out problems with another hypothesis that time travel is possible, but travelers themselves will be limited in what they do – this stops them from creating the paradox. In this model, time travelers can do whatever they want, but paradoxes are impossible.

But despite the figures and the results obtained, the main problem of time travel remains the curvature of space and time needed to get into the past – the time machines that scientists have developed so far are so highly reliable that now exist only as calculations on a page. And yet the researchers are optimistic, because their work assumes that we will be free to do with the world whatever we want in the past: it will be rebuilt accordingly.