Paradox-free time travel is theoretically possible, according to the mathematical modelling of a student-teacher duo from the University of Queensland, in Australia.
A new study by Germaine Tobar, a fourth-year student, who has been investigating the possibility of time travel under the supervision of physicist Dr Fabio Costa, suggests that it is possible to go back in time, theoretically. History, however, cannot be changed.
“Einstein’s theory of general relativity predicts the existence of time loops or time travel – where an event can be both in the past and future of itself – theoretically turning the study of dynamics on its head,” said Tobar to the University of Queensland.
A unified theory that allowed both traditional dynamics and Einstein’s theory of relativity to coexist is the ‘holy grail’ of physics, but this is not possible according to current science, says Tobar.
The grandfather paradox is a logical dilemma that arises because of Einstein’s theory. The theory makes it feasible for a person to travel through time and kill their grandfather, which would make their own birth impossible. While this does not mean that time travel is impossible, it makes it logically hard to accept.
Scientists, and makers of science-fiction, have both grappled with this problem in their work.
“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,” he said.
In the study, published in the peer-reviewed journal Classical and Quantum Gravity, Tobar and Costa ‘squared the numbers’ and found that even if time travel existed the paradox could not.
“The maths checks out – and the results are the stuff of science fiction,” said Costa.
The scientists used the coronavirus pandemic to formulate their own paradox to help make sense of the situation. In this scenario, a person would travel in time in an attempt to stop patient zero from being exposed to COVID-19. If the person successfully prevented infection it would eliminate the motivation for them to go back in time to stop the pandemic in the first place.
Tobar and Costa say their research shows that such a paradox would not necessarily exist because events would adjust themselves.
“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,” said Tobar.
In short, no matter what the time traveller does the original outcome would still happen even if it differed slightly from the way it transpired the first time around.
The time traveller would still exist and their motivations to go back in time and stop the event would endure.
“No matter what you did, the salient events would just recalibrate around you,” explained Tobar.
Time travel is a recurring theme in the books of bestselling science fiction author Blake Crouch, who told NPR that the study seems to support what certain time travel cliches have proposed all along.
“The universe is deterministic and attempts to alter Past Event X are destined to be the forces which bring Past Event X into being.
“So the future can affect the past. Or maybe time is just an illusion. But I guess it’s cool that the math checks out.”