04/12/2020

Mathematical model suggests it's possible to travel back in time.

Foto: Agência Brasil

Imagine going back to 2019, a time before the coronavirus pandemic, and being able to prevent the spread of the virus that has so drastically changed the year we are living through. This almost impossible mission would also involve finding patient zero, minutes before they were infected. A trip to the past to avoid future problems seems quite appealing, doesn't it? But a mathematical detail, which is being analyzed by researchers, is still one of the obstacles preventing this from becoming a reality.

Some interpretations of theoretical physics suggest that being a time traveler is possible. Albert Einstein, for example, knew that his equations allowed, at least in theory, time travel. Such theoretical journeying, however, runs into what scientists call a "paradox."

A "paradox," as scientists call it, is an infinite loop that creates a logical inconsistency and destroys the illusion of time travel. Among the most famous models is the "grandfather paradox." Its original version presents a scenario in which the grandson would travel through time to kill his own grandfather, even before he had his father. The big issue is that, once the grandfather was dead, the traveler could not have been born. Without the birth in question, time travel would also not be feasible.

Solving this paradox involves several mental exercises. Recently, Germain Tobar, a physics student at the University of Queensland in Australia, under the supervision of Professor Fabio Costa, a philosopher and theoretical physicist, developed a mathematical solution to the problem. Their proposal is a mathematical model with which they calculated that an "agent" entering a time travel loop could follow different paths without altering the outcome of their actions.

The abstract exercise shows that various agents can communicate in the past and present without establishing a cause-and-effect relationship. "Events adjust themselves, so there will always be a single, consistent solution," Tobar points out to the BBC . Considering the example of the pandemic, the study suggests that in a trip to the past it would be possible to do anything, but it would be impossible to change the outcome of events. In other words, you would have free will, but you wouldn't be able to prevent the pandemic from spreading. Among all the possibilities analyzed, even you, as a time traveler, could be patient zero.

The model proposed by Tobar shows that the most relevant events would be constantly calibrated to avoid any paradox, always reaching the same result. This study is only applicable in an abstract way in the field of mathematics. “It’s interesting work,” points out Chris Fewster, a mathematics professor at the University of York in the UK who studies time travel models, to the reporter.

Fewster reminds us that "it remains to be seen whether the abstract conditions imposed by the authors are satisfied by currently known theories of physics." The challenge now is to put this mathematical model to the test and, who knows, perhaps even travel through time!

Source: BBC