A study by a Brock University professor has revealed that time travel might be possible if parallel timelines are involved.
In an article for The Conversation, physicist Barak Shoshany of Brock University in Canada suggests that time travel could be possible in real life. There is, however, a small twist.
To begin with, there is a practical issue: in order to build a time machine, a large amount of exotic matter – matter with negative energy — would be required. All matter on Earth contains positive energy, and while quantum physics suggests that exotic matter may be formed in theory, it would be in insufficient quantities and for insufficient periods of time.
Second, time travel, according to Shoshany, could leave science fiction’s pages, but only when parallel timelines are involved. This is because of the time paradox, also known as the consistency paradox.
In movies and literature, time travellers are cautioned against engaging with their past selves or altering history in any way – because killing their own grandfather, for example, would theoretically prevent them from ever being born, let alone travelling back in time.
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The impossibility of time travel is demonstrated by these paradoxes. There would be no paradox if parallel timelines existed, allowing a time-traveller to jump across into an alternate history leading to an alternate present.
According to Shoshany, this suggests that time travel is possible if our universe permits many histories to coexist in some way. This is the subject of a separate study, which the physicist is already conducting with the assistance of his students.
“My students and I are currently working on finding a concrete theory of time travel with multiple histories that is fully compatible with general relativity. Of course, even if we manage to find such a theory, this would not be sufficient to prove that time travel is possible, but it would at least mean that time travel is not ruled out by consistency paradoxes,” Shoshany said in his article.
He pointed out that quantum mechanics suggests the existence of a “multiverse,” as some call it. The paradox of Schrödinger’s Cat is a well-known example. The cat in the box dies in one timeline but lives in another, parallel one.
So, if our world can sustain numerous histories, it appears that we would be able to travel across time — even if we would still be spectators rather than players, given that nothing could be changed.