Two mathematicians argue that the logical inconsistency that is believed to underlie time travel does not actually exist, and therefore it is theoretically possible for someone to travel back in time and change reality. "If time is simply the fourth dimension, then it is natural to ask ourselves why we cannot move through it. 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 in its future, explains Germain Tobar, a student at the University of Queensland, Australia, quoted by IFL Science .

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When we talk about time travel, experts remind us of the "grandparents' paradox" to explain why such an effort is impossible. Thus, if a traveler prevents his grandparents from meeting, he will no longer exist and, therefore, will never be able to prevent the meeting. Many science fiction writers who have dealt with the subject of time travel have "bypassed" the problem, so that their characters change only aspects that do not prevent their own existence.

Time travel is not subject to science fiction logic

How do the two solve this paradox? Their solution indicates that the universe would adjust, although the model the two describe in their paper involves a simplified world in which cause and effect are represented by billiard balls hitting each other, they suggest that more complex human environments work. as.

"In the COVID-19 zero-patient example, we could try to stop the zero-patient infection, but by doing so, someone else will become the zero-patient," Tobar said. Although we may change history, these changes would be made only in such a way that we still exist and we have a reason to make such a journey, avoiding any paradox.

If time travel is possible , we might wonder, in a version of Fermi's paradox, why future travelers have not visited us, or to attend events to which they have been specifically invited. "While time travel is logically possible, there may be additional restrictions," Tobar said. "Alternatively, events revolve around anything that could cause a paradox, so that the paradox doesn't happen, so maybe someone actually came back, but it didn't become a public event. Thus, instead of government cover-ups, the laws of physics could be the ones that hide the truth.