According to a new theoretical study that appeared on arXiv, taken from Futurism and New Scientist, in the context of the theory of parallel universes, it might be possible to travel from the timeline of one universe to the timeline of another by crossing a wormhole, i.e. a hole in space-time.
The two physicists who carried out the research, Jacob Hauser and Barak Shoshany, assume that if time travel is possible it inevitably leads to unexplained paradoxes. Think for example of the simple paradox of their grandfather, a paradox that has always puzzled physicists.
This paradox could be solved by taking into consideration the possibility of the existence of parallel universes, an idea that is certainly not new to explain time travel that this study puts on the table, however, emphasizing the fact that there is no need for an infinite number of universes, even if it would be necessary a number that remains very large.
As Shoshany explains to New Scientist, the idea that the two physicists suggest starts from the theoretical concept that there are many parallel universes within which things and events are more or less the same even if each parallel universe travels on a separate space-time line. These lines can also be traveled to travel back in time.
Multiple timelines would allow a hypothetical time traveler to kill his or her grandfather and not cause time paradoxes that could lead to consequences that even physicists themselves could not explain. The theory of the two physicists predicts that any change is made to the past is independent of the history of the timeline from which the time traveler comes.
As explained by another researcher, Geraint Lewis of the University of Sydney, not involved in the research, it wouldn’t be a real time travel: for example, it wouldn’t make more sense to go back in time and kill Hitler to avoid the Second World War if this war didn’t take place in the universe from which it came.
And this would also be true if the universe from which you came would be substantially the same as the universe in which you made the modification in the past: even a single atom positioned differently from the universe of origin would be enough to label the universe “modified” as a parallel and distinct universe.