No one has been able to travel through time – to our knowledge at least – but the question of whether it would be possible to do such a trick theoretically continues to pique the interest of scientists.
As movies as The Terminator, Donnie Darko, Back in the future and many others show, moving around in time creates a lot of problems for the basic rules of the Earth: if you go back in time and stop your parents from meeting, for example, how can you be there to go back in time in the first place?
It’s a memorable headache called the ‘grandfather paradox’, but last September physics student Germain Tobar, from the University of Queensland in Australia, said he had worked out how to e “number square” to enable time travel. without the paradoxes.
“Classical dynamics says if you know the state of a system at a particular time, this can tell us the whole history of the system,” Tobar said back in September 2020.
“However, Einstein’s theory of universal relativity predicts that there will be time loops or time travels – where an event can be both past and future alone – theoretically turn a dynamic study on its head. “
What the calculations show is that space time can change into avoiding paradoxes.
To use a contemporary example, imagine a time traveler traveling into the past to stop a disease from spreading – if the mission was successful, the person would not be infected -travel time to go back in time to make it happen.
Tobar’s work suggests that the disease would still escape in another way, through a different path or in a different way, removing the paradoxes. No matter how long the passenger traveled, the infection would not stop.
Tobar’s work is not easy for non-mathematical people to dig into, but it looks at the effect of definite (no-guess) processes on an irregular number of segments in the place-time continuum, and shows how the two closed timelike loops (as predicted by Einstein) conform to the rules of free will and classical physics.
“The mathematical studies study – and the results are like science fiction material,” said physicist Fabio Costa of the University of Queensland, who led the research.
Fabio Costa (left) and Germain Tobar (right). (Ho Vu)
The new research solves the problem with another hypothesis, that time travel is possible but that time travelers would be limited in what they have done, to stop them from creating paradoxes. In this model, time travelers have the freedom to do anything they want, but paradoxes are not possible.
While the numbers may work out, in fact there is a shift of space and time to getting into the past – the time machines that scientists have not designed so far so highly of an idea that currently exists only as a numbering on a page.
We may get there one day – Stephen Hawking certainly thought it was possible – and if we do then this new research suggests that we would be free to do anything we wanted to do to the the world in the past: it would be okay accordingly.
“See how you can create paradoxes, the events always change themselves, to avoid any inconsistencies,” says Costa. “The range of mathematical processes we have found shows that free-time travel is logically possible in our universe without any paradoxes.”
The research was published in Classical and Quantum Gravity.
A draft of this article was first published in September 2020.