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Australia A Physicist Has Come Up With Math That Makes 'Paradox-Free' Time Travel Plausible

03:16  27 september  2020
03:16  27 september  2020 Source:   sciencealert.com

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No one has yet managed to travel through time – at least to our knowledge – but the question of whether or not such a feat would be theoretically possible continues to fascinate scientists. As movies such as The Terminator, Donnie Darko, Back to the Future and many others show, moving around in

Time travel isn't just science fiction: Albert Einstein's general relativity suggests it could exist. And now we might have solved the tricky matter of time Various workarounds have been proposed over the years - Oxford physicist David Deutsch came up with an intriguing possibility in the early 90s when

  A Physicist Has Come Up With Math That Makes 'Paradox-Free' Time Travel Plausible © andrey_l/Shutterstock

No one has yet managed to travel through time – at least to our knowledge – but the question of whether or not such a feat would be theoretically possible continues to fascinate scientists.

As movies such as The Terminator, Donnie Darko, Back to the Future and many others show, moving around in time creates a lot of problems for the fundamental rules of the Universe: if you go back in time and stop your parents from meeting, for instance, how can you possibly exist in order to go back in time in the first place?

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Time travel — moving between different points in time — has been a popular topic for science fiction for decades. Each come with their own time travel theories. While Einstein's theories appear to make time travel difficult, some groups have proposed alternate solutions to jump back and forth in

Travelling in time might sound like a flight of fancy, but some physicists think it might really be possible. Prof Mallett has wanted to build a time machine for most of his life. His passion, he explains, can be traced to a tragic event early in his life.

It's a monumental head-scratcher known as the 'grandfather paradox', but now a physics student Germain Tobar, from the University of Queensland in Australia, says he has worked out how to "square the numbers" to make time travel viable without the paradoxes.

"Classical dynamics says if you know the state of a system at a particular time, this can tell us the entire history of the system," says Tobar.

"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 future of itself – theoretically turning the study of dynamics on its head."

What the calculations show is that space-time can potentially adapt itself to avoid paradoxes.

To use a topical example, imagine a time traveller journeying into the past to stop a disease from spreading – if the mission was successful, the time traveller would have no disease to go back in time to defeat.

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Even the slight possibility of time travel exerts such fascination that many physicists continue to "Is it possible to travel through time ? To answer this question, we must be a bit more specific about (Note that there is no 'twin paradox ,' because it is unambiguous that the space traveler has felt the

TIME travel into the distant future or ancient past is a possibility, according to science, but the requirements for a working time travel machine can be tricky to achieve. Time travel : Physicists believe time travel into the future is possible (Image: GETTY).

Tobar's work suggests that the disease would still escape some other way, through a different route or by a different method, removing the paradox. Whatever the time traveller did, the disease wouldn't be stopped.

Tobar's work isn't 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 timelike curves (as predicted by Einstein) can fit in with the rules of free will and classical physics.

"The maths checks out – and the results are the stuff of science fiction," says physicist Fabio Costa from the University of Queensland, who supervised the research.

a group of people looking at each other: Fabio Costa © left) and Germain Tobar (right). (Ho Vu Fabio Costa

The new research smooths out the problem with another hypothesis, that time travel is possible but that time travellers would be restricted in what they did, to stop them creating a paradox. In this model, time travellers have the freedom to do whatever they want, but paradoxes are not possible.

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The Paradox -Correcting Time Travel Machine is a big green orb that possesses the capacity for time travel . It is summoned to Earth by Bender Bending Rodríguez reading a sequence of binary code tattooed to Fry's behind.

Physics support the possibility of time travel to the future. Time travel to the future? Definitely possible. We know how to do it because Einstein showed us the way over a hundred years ago. Albert Einstein again discovered. The guy has like got his name written over everything in this field.

While the numbers might work out, actually bending space and time to get into the past remains elusive – the time machines that scientists have devised so far are so high-concept that for they currently only exist as calculations on a page.

We might get there one day – Stephen Hawking certainly thought it was possible – and if we do then this new research suggests we would be free to do whatever we wanted to the world in the past: it would readjust itself accordingly.

"Try as you might to create a paradox, the events will always adjust themselves, to avoid any inconsistency," says Costa. "The range of mathematical processes we discovered show that time travel with free will is logically possible in our universe without any paradox."

The research has been published in Classical and Quantum Gravity.

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