No one has yet experienced time travel, at least to the best of our knowledge, but scientists remain curious about the possibility of humanity achieving such a feat.
As shown by films such as “The Terminator”, “Donnie Darko”“Back to the Future’ and many others, time travel creates many problems related to the fundamental rules of the Universe. If you travel through time and stop your parents’ first meeting, how is it possible to still exist and go back in time?
Time travel is a monumental problem known as the “grandfather paradox”, aptly Science Alert.
The paradoxes could be avoided, according to the calculations
A few years ago, physics student Germain Tobar from the University of Queensland, Australia, found a way to “square the numbers” to make time travel viable without paradoxes.
“Classical dynamics says that if you know the state of a system at a given time, that can tell us the entire history of the system. However, Einstein’s theory of general relativity predicts the existence of time loops or time travel when an event takes place simultaneously in the past and the future, which theoretically turns the study of dynamics upside down,” Tobar said.
What the calculations show is that space and time can adapt so as to avoid paradoxes. For example, imagine a time traveler who goes back in time to stop the spread of a disease. If the mission had been successful, the time traveler would not have had to go back in time to stop any disease.
Tobar’s study, published in Classical and Quantum Gravity, suggests that the disease would have escaped in some way anyway, by a different direction or method, removing the paradox. No matter what the time traveler did, the disease would not be stopped.
What would allow time travelers a possible return to the past?
Tobar’s work is not easy to fathom for non-mathematicians. It analyzes the influence of deterministic processes on an arbitrary number of regions of the space-time continuum and demonstrates how time loops (as predicted by Einstein) fit both the rules of free will and those of classical physics.
“The math checks out and the results are science fiction,” said University of Queensland physicist Fabio Costa, who led the research.
The research mitigated the problem with another hypothesis, that time travel is possible, but time travelers would be restricted in what they do, so as not to create another paradox. In this model, time travelers are free to do whatever they want, but paradoxes are not possible.
Changing past events would readjust the present accordingly
While the numbers might work, the curvature of space and time to reach the past remains elusive. The time machines that scientists have devised so far are so sophisticated that they currently exist only as calculations on a page.
We may get there one day, though. Stephen Hawking certainly thought this was possible. And if we succeed, then this new research suggests that we’d be free to do whatever we wanted with the world of the past, but it would readjust accordingly.
“No matter how much you try to create a paradox, events will always adjust themselves to avoid any inconsistency. The range of mathematical processes we have discovered shows that, in fact, free will time travel is possible in our Universe, without any paradox,” said Fabio Costa.