Paradox-free time travel theoretically possible, scientists say

Countless books and movies have explored the idea of time travel, a fascinating concept among science-fiction fans and scientists, and new research suggests that the film “Back to the Future” may not be so far-fetched.

Germain Tobar, a bachelor of advanced science student at the University of Queensland, has been investigating the possibility of time travel under the supervision of physicist Dr. Fabio Costa and found that paradox-free time travel is theoretically possible.

“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,” Tobar said. “I wondered: Is time travel mathematically possible?”

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In the paper, titled “Reversible dynamics with closed time-like curves and freedom of choice,” Tobar worked out how to "square the numbers" to make time travel viable without paradoxes.

“The maths checks out – and the results are the stuff of science fiction,” Costa said.

The paper cited the example of traveling back in time in an attempt to stop COVID-19’s patient zero from being exposed to the coronavirus.“However if you stopped that individual from becoming infected – that would eliminate the motivation for you to go back and stop the pandemic in the first place,” Tobar said.


A poster for George Pal's 1960 adventure film 'The Time Machine'.

This is a paradox that usually leads people to think that time travel cannot occur in our universe.

“It would mean you can time travel, but you cannot do anything that would cause a paradox to occur,” Tobar said.

But Tobar and Costa say that it is possible for events to adjust themselves to be logically consistent with any action that a time traveler makes.

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“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,” Mr Tobar said. “No matter what you did, the salient events would just recalibrate around you.”

Thus, the new research suggests an individual would have the freedom to do what he wanted in the past, but the events would always adjust themselves accordingly to avoid any inconsistency with future events.

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