Time Travel Is Totally Possible (in Virtual Reality)

Much has been said about virtual reality taking viewers to different places, but a recent study takes on another dimension: time. Researchers from the University of Barcelona and the Interdisciplinary Center Herzliya in Israel put together a virtual reality experience that lets volunteers experience time travel.

According to their paper, published in the journal Frontiers in Psychology, it worked. Participants felt as if they had travelled back in time and—here's the kicker—that they could change the past. The paper explained that the illusion of time travel was successful, provided that subjects "also experienced an illusion of presence in the virtual environment, body ownership and agency over the virtual body that substituted their own."

Virtual reality is immersive enough that you think it's real. That's why it proved to be an ideal vehicle to induce feelings of time travel.

"It is not comparable to watching a video or playing a game on the screen," PhD student Rodrigo Pizarro, one of the authors of the paper, told me. "The difference is very significant. When you're in virtual reality you suddenly forget you're in a physical space; you very quickly assume you are in that virtual environment."

The idea was to see what effect time travel has on people, "irrespective of whether time travel to the past is in any way possible," as the researchers explain in their paper. While direct, real-world parallels may seem more than a little far-fetched, the experience they developed is interesting on several psychological and philosophical levels.

They based their dimension-twisting test on the famous "trolley problem," a hypothetical moral dilemma that  has been given the VR treatment before. In the VR world, participants first experienced an event in a gallery with two floors, and they could operate a lift to take other avatars to the upper level. But upon reaching the top floor, one visitor avatar takes a gun out of his pocket and starts shooting.

There are five people on the upper level, and one on the lower floor. It's the classic conundrum: Do you send the lift back down and sacrifice the one person to save the remaining survivors on the top floor? If you were really quick-thinking in this particular study, you might have been able to jam the lift between floors too.

In the study, 32 participants then had one of two possible VR experiences. Those in the "repetition" model repeated the same exact scene, just like if you lost a life in a video game and respawned. Those in the "time travel" strain also went back to the start, only they could see an "incarnation" of their previous self's actions. And then they did it all again, a third time.

Pizarro explained that one of their main findings was that those who underwent the time travel condition felt less guilty, which he said was "consistent with the idea that muting the past would lead to a more comforting feeling."

Which brings us to some of the potential real-world applications of time travel VR illusions. One could be for use in psychological therapy, such as to treat post-traumatic stress disorder. "If people could replay an event that caused trauma, for example, that could be a possible treatment," said Pizarro.

However, it's early days—the study was small and experimental—and the researchers emphasised that psychotherapists would have to be consulted to develop such an application.

But Doron Friedman, one of the study's principal investigators, said virtual reality in general could be a useful therapeutic tool to "put you in a situation that might be a bit unpleasant without the actual risk."

He added that their findings might also inform the potential for a time travel option in video games, especially immersive digital realms in the vein of Second Life. "This is just scratching the surface of the possibilities," he told me. "The technology is very complicated and raises a lot of questions; it's on the border of philosophy."

Indeed, one of the most interesting aspects of the research could be its role in exploring some of the most popular philosophical problems with time travel, like the grandfather paradox (i.e. if you go back in time and kill your grandfather so you're never born, how can you then go back in time to kill your grandfather?).

It might not solve the paradox, but perhaps VR software could help offer new, more hands-on ways of looking at the limits of theoretical time travel. Or at the very least, help make sense of the plot of Looper.