# Mathematics Does Not Prohibit Traveling Back in Time

What more exciting possibility does physics raise than time travel? We all dreamed of an opportunity to visit the Triassic or repeat an exam in “the DeLorean.” Of all the paradoxes that our interpretation of physical phenomena brings us, probably the most perplexing is the concept of time. Is there a mechanism that allows a trip to an earlier period? At least, mathematically speaking, it seems “yes.”

Traveling to the future is possible, although nothing is simple. According to Einstein’s Relativity, any observer moving at a certain speed is, in some way, traveling into the future for a static observer. It is because, for the observer, rest time passes more slowly.

Astronauts living on the International Space Station move considerably faster than we do on the Earth’s surface, so their biological clocks are slightly ahead. Of course, this effect is negligible in astronauts. But if we could move at speeds closer to that of light, the consequences would be noticeable. An illustrious example is what happens to the character Matthew McConaughey, who returns home after orbiting a black hole to find that his daughter is several decades older than him.

But traveling back is prohibited by the known laws of physics, as it violates causality, an unbreakable relationship between a cause and an effect. The grandfather paradox is the most concrete example of this prohibited violation. A grandson travels back in time and kills his grandfather so his father cannot be born, and consequently, neither can he. So he couldn’t have traveled back in time, and his grandfather would still be alive, resulting in the grandson being born and being able to travel back in time to kill his grandfather. And so infinitely.

Germain Tobar is a fourth-year science student at the University of Queensland in Australia. Tobar and his supervisor, Dr. Fabio Costa, explored the mathematical (not physical) possibilities of providing a model to prove that a trip to the past is possible. They found a way to make the numbers square so that the journey is plausible and avoid the emergence of paradoxes like the grandfather.

“It would mean you can time travel, but you can’t do anything to cause a paradox,” Dr. Costa said in an official press release for the University of Queensland.

Establishing an accurate description of the mathematically possible phenomena is the first step to physical experimentation, even reinforcing or reformulating the postulates of Relativity. In this sense, all the explored possibilities have enormous scientific value.

“The range of mathematical processes we discovered shows that free will time travel is logically possible in our universe without any paradox,” Costa concludes.