Physicists Prove Time-Travel Is Theoretically "Possible", But Changing The Past Is Not

Authored by Elias Marat via,

Researchers at the University of Queensland, Australia, claim to have proven that time travel is theoretically possible according to the laws of physics.

However, we needn’t fear that time-travelers would somehow travel to the past and alter the present-day, as is the case in myriad science fiction scenarios – instead, the future would remain the same, according to the researchers’ calculations.

“Events readjust around anything that could cause a paradox, so the paradox does not happen,” study author Germain Tobar told IFLScience.

His study, which was published in the journal Classical and Quantum Gravity, details how according to the rules laid down by theoretical physics, any changes impacting the past would be subsequently corrected by the events that followed. So don’t expect to succeed in drastically altering history, even if you do go back in time on a mission to kill Hitler in his crib.

Physicists used mathematical modeling to reconcile classic dynamics with Einstein’s theory of general relativity. The contradiction between the two systems is a longtime flaw in time travel concepts, known as the grandfather paradox.

“As physicists, we want to understand the universe’s most basic, underlying laws and for years I’ve puzzled on how the science of dynamics can square with Einstein’s predictions,” said Tobar. “Is time travel mathematically possible?”

According to classical dynamics, any attempt by a time traveler to go back in time and, say, kill their grandfather, would result in the time traveler never coming into existence in the first place.

Within Einstein’s theoretical framework, however, a person could go back in time to kill their grandfather. This is because he calculated that an object in our universe could travel through both time and space in a circular direction before ultimately ending up where it had been before – a path known as the closed time-like curve.

Tobar and his colleagues used the ongoing coronavirus pandemic as their basis for the study, and imagined if a time traveler had gone back to prevent “patient zero” from being infected.

“In the coronavirus patient zero example, you might try and stop patient zero from becoming infected, but in doing so you would catch the virus and become patient zero, or someone else would,” Tobar explained.

“No matter what you did, the salient events would just recalibrate around you,” he continued. “This would mean that – no matter your actions – the pandemic would occur, giving your younger self the motivation to go back and stop it. Try as you might to create a paradox, the events will always adjust themselves to avoid any inconsistency.”

“The range of mathematical processes we discovered show that time travel with free will is logically possible in our universe without any paradox,” Tobar added.

In other words, any attempt to kill your grandfather would mean that something or someone would intervene to prevent this from happening – or, at the very least, your mother would already be a fetus in your grandmother’s womb by the time he did perish.

Dr. Fabio Costa, the University of Queensland physicist who supervised the project, noted: “The math checks out – and the results are the stuff of science fiction.”