Scientists solve time travel paradox – but still no time machine

Although the technology to do so does not (yet) exist, this doesn’t stop theoretical physicists from contemplating the nature of time travel. One speed bump in the theory of time travel has always been the Grandfather Paradox: if you go back in time to kill your grandfather before he had children then you would cease to exist, making it impossible that you would have been able to travel to the past to kill him in the first place.

As soon as they arrive, they inadvertently change history by their mere presence, whether they want to or not

Scientists Jacob Hauser and Barak Shoshany published a paper setting out a possible solution to this paradox: time travel triggers multiple histories (or multiple timelines). Essentially, as the individual arrives in the past, another timeline is created at that moment.

“If one wanted to go back in time to see the dinosaurs, they can certainly do that, and the world they will arrive at will indeed be the same world from which they left, with the same dinosaurs, up to the moment of arrival,” explain the authors.

“However, as soon as they arrive, they inadvertently change history by their mere presence, whether they want to or not. Thus, by definition, they must have arrived at a different history.”

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Now, I know you're waiting for Elon Musk to create a Tesla cybertruck version of the DeLorean so you can get started but, unfortunately, as the authors point out, they didn't come up with "an actual physical mechanism for creating new histories".

[ https://arxiv.org/pdf/1911.11590.pdf ]