A method can make time travel possible, according to this physicist. | Science and environment news

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Have you ever made a mistake that you would like to undo? Correcting the mistakes of the past is one of the reasons why the concept of time travel seems so fascinating to us, as it is often portrayed in science fiction using a time machine, but is time travel in our universe really possible or is it just science fiction? A question asked by physicist Barak Shoshani in an article on the Sanis Alert website.

Our modern understanding of time and cause comes from general relativity, where the theory of theoretical physicist Albert Einstein combines space and time into a single entity – “space-time” – and offers an extremely complex explanation of how both work “, on a level incomparable to any other. theory”, says Shoshani. other well placed.

For decades physicists have tried to use the theory of relativity to see if time travel is possible, and it turns out that equations describing time travel can be written and are fully compatible and consistent with relativity, but physics is not mathematics, and the equations are meaningless if they do not correspond to anything in Reality.

Arguments against time travel

There are two main issues that make us think that these equations may be unrealistic. The first issue concerns the construction of a time machine that requires matter with negative energy, which is a substance that you can not find around you, but by mechanics quantum. we know that such a subject can theoretically be created in very small quantities, for very short periods of time.

However, there is no evidence that it is impossible to form exotic matter in sufficient quantities and other equations can be discovered that allow time travel without the need for this exotic matter.

Another key issue is that time travel goes against logic, especially the paradoxes of time travel and the consistency of events.

Paradoxes are removed

There is a common misconception in science fiction that paradoxes can be “created” and time travelers are usually warned not to make big changes in the past and to avoid meeting their former selves precisely for this reason.

But in physics, a contradiction is not an event that can actually happen, because it is a purely theoretical concept that refers to a contradiction in the theory itself. In other words, the paradoxes of symmetry mean not only that time travel is a dangerous endeavor, but that it is simply impossible.

This was one of the motivations for theoretical physicist Stephen Hawking to formulate his chronological defense conjecture, which says that time travel should be impossible, but this conjecture has not yet been proven.

Moreover, the universe would be a much more interesting place if, instead of eliminating time travel due to paradoxes, we could eliminate the same paradoxes.

An attempt to solve the paradox of time travel is the assumption of the self-consistency of the theoretical physicist Igor Dmitrievich Novikov, who basically says that you can travel to the past, but you can not change it.

According to this scientist, “If I were to try to destroy my time machine for five minutes in the past, I would be unable to do so. “The laws of physics will somehow conspire to maintain stability.”

Enter multiple dates

So what is the point of going back in time if you can not change the past? Physicist Shoshani says: “My latest work, together with my students Jacob Hauser and Jared Wogan, shows that there are paradoxes in time travel that Novikov’s conjectures cannot solve, and this brings us to the square, because if a the paradox alone cannot be eliminated. , then time travel remains logically impossible.

But this is not the last nail in the coffin of time travel, according to the physicist, who says he and his team have demonstrated that allowing multiple dates (or parallel timelines) can resolve contradictions that Novikov’s conjecture does not can do it.

“The idea is very simple,” he says. When I get out of the time machine, I go out to another timeline where I can do whatever I want, including destroying the time machine without changing anything in the original timeline I came from, as I can not destroy the time machine in time original, which is the time limit. There is no contradiction in the timeline you have already used for time travel. ”

“After working on the paradoxes of time travel for the last three years, I have become more and more convinced that maybe time travel is possible, but only if our world allows multiple stories to coexist,” says Shoshani.

“My students and I are currently working on a concrete theory of time travel with multiple stories that are completely consistent with general relativity. Of course, even if we could find such a theory, it would not suffice to prove that time travel is possible, but at least it would mean that time travel is not excluded from the paradoxes of consistency.

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