No one has yet managed to travel through time – at least to our knowledge – but the question of whether such an achievement would be theoretically possible or not remains fascinating to scientists.
Like movies like The Terminator, Donnie Darko, Back to the future and many others show that the movement of time creates many problems for the fundamental rules of the Universe: for example, if you go back in time and prevent your parents from meeting, how can you exist to return to the universe? time in the first place?
It’s a monumental puzzle known as the ‘grandfather paradox’, but in September last year a physics student Germain Tobar, from the University of Queensland in Australia, said he had worked out how to calculate the numbers. square to make time travel viable. without the paradoxes.
“Classical dynamics say that if you know the state of a system at a particular time, it can tell the entire history of the system,” Tobar said in September 2020.
“However, 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 the future in itself – and the study of dynamics theoretically turns on its head.”
What the calculations show is that space-time can possibly adjust itself to avoid paradoxes.
To use a current example, imagine that a time traveler travels in the past to stop a disease from spreading – if the mission was successful, the time traveler would have had no illness to return to defeat.
Tobar’s work suggests that the disease would still escape in a different way, in a different way or in a different way, which would remove the paradox. Whatever the traveler did, the disease would not be stopped.
Tobar’s work is not easy for non-mathematicians to dig into, but it looks at the influence of deterministic processes (without any randomness) on an arbitrary number of regions in the space-time continuum, and demonstrates how both closed temporal curves (as predicted) by Einstein) can fit into the rules of free will and classical physics.
“Mathematics is going out – and the results are science fiction,” said physicist Fabio Costa of the University of Queensland, who oversaw the research.
Fabio Costa (left) and Germain Tobar (right). (Ho Vu)
The new research eases the problem with another hypothesis, that time travel is possible, but that time travelers will be limited to what they have done, to prevent them from creating a paradox. In this model, time travelers have the freedom to do what they want, but paradoxes are not possible.
While the numbers may work out, the space and time to move in the past remains elusive – the time machines that scientists have devised so far are such a concept that they currently exist only as calculations on a page.
We may one day get there – Stephen Hawking certainly thought it was possible – and if we do, this new research suggests that in the past we would be free to do what we want with the world: it will do itself accordingly. adapt.
“Trying to create a paradox as much as possible, the events will always adapt themselves to avoid any contradiction,” Costa says. “The variety of mathematical processes we have discovered shows that free-travel time travel is logically possible in our universe without any paradox.”
The research was published in Classical and quantum gravity.
A version of this article was first published in September 2020.