Time Travel Is Possible… But Only For Parallel Universes?
From HG Wells’ “The Time Machine” to the “Back to the Future” franchise, time travel has been a hallmark of science fiction for over a century.
Part of its appeal was that famous physicists like Albert Einstein created theories that explain weather phenomena in ways that don’t rule out the possibility of time travel.
Einstein’s special theory of relativity proposes that time moves relative to an observer and is an illusion.
In his 1905 theory, space and time combined into a singular entity known as “spacetime,” which physicists were able to verify.
However in an article published in The Conversation Barak Shoshany, assistant professor of physics at Brock University in Canada wrote about the possibility of time travel, but with certain conditions.
One of the biggest obstacles to time travel is the practical requirement of “exotic matter” which is matter with negative energy, as opposed to the matter around us which consists of positive energy.
However, Professor Shoshany adds that there is no evidence that it is impossible to create exotic matter in sufficient quantities.
“In addition, other equations can be discovered that allow time travel without requiring exotic matter”, explains Professor Shoshany.
Another obstacle is the possibility of temporal paradoxes where an action taken in the past can have ripple effects in the present that undo the need for time travel.
A classic example of this is the famous “grandfather paradox” where experts ponder whether a time traveler would cease to exist if he went back in time to kill his grandfather as a young man.
“In physics, a paradox is not an event that can actually happen, it is a purely theoretical concept that points to an inconsistency in the theory itself”, adds the Canadian physicist.
“In other words, consistency paradoxes not only imply that time travel is a dangerous undertaking, but that it simply cannot be possible.”
Theoretical physicist Igor Dmitriyevich Novikov tried to solve the problem of time travel paradoxes with a self-consistency conjecture that essentially states that you can travel to the past, but you cannot change it.
But Professor Shoshany along with his students Jacob Hauser and Jared Wogan studied time travel and in a recent study they found that there are time travel paradoxes that the Novikov conjecture cannot resolve.
“We show that allowing for multiple stories (or in more familiar terms parallel timelines) can resolve paradoxes that the Novikov conjecture cannot,” writes Shoshany.
“In fact, it can resolve any paradox you throw at it.”
According to his theory when a person leaves a time machine they arrive in a different timeline where they can do whatever they want, including destroying their time machine five minutes before using it.
In this theory changes in this new timeline would have no effect on the original timeline.
“After working on the paradoxes of time travel for the past three years, I have become increasingly convinced that time travel might be possible, but only if our universe allows multiple stories to coexist,” he continues. explaining the physique
The research team now seeks to formulate a concrete theory of time travel that conforms to the law of general relativity.
Professor Shoshany adds that even if they manage to find such a theory it would not be enough to prove that time travel is possible, but at least it would mean that time travel is not ruled out by consistency paradoxes.
Bottom line: Multiple timelines would allow you to travel to a different timeline and kill your grandparents, let’s skip the ‘why’ for debate, without causing a paradox.
Of course, once this happens there is no reason to believe that this Universe will continue exactly like ours.
It is likely that the “butterfly effect” of your arrival has changed, it is also likely that you have selected a limited number of similarities no matter how great.
Even so, this would be a way (still extremely far-fetched) of experiencing the past, without affecting the present or creating paradoxes.