From HG Wells’s “The Time Machine” to the Avengers: Endgame, travelling through time has been a hallmark of science fiction for over a century. Part of its appeal has been that famous physicists such as Albert Einstein have come up with theories that explain the phenomena of time in such a way that it doesn’t rule out the possibility of time travel. Einstein’s theory of special relativity proposes that time moves relative to an observer and is an illusion.
In his 1905 theory, the combined space and time into a singular entity known as “spacetime”, which physicists over the next century have verified.
In an article published in the Conversation, Assistant Professor of Physics at Brock University, Barak Shoshany, wrote about the possibility of time travel- with a catch.
One of the biggest obstacles to time travel is the practical requirement for “exotic matter”, which is matter with negative energy, unlike the matter around us, which consists of positive energy.
However Prof Shoshany added: “There is no proof that it is impossible to create exotic matter in sufficient quantities.
“Furthermore, other equations may be discovered that allow time travel without requiring exotic matter.”
Another obstacle is the possibility of time paradoxes, where an action taken in the past could have ripple effects in the present that undo the need to time travel in the first place.
A classic example of this is the famous “Grandfather paradox”, where experts ponder over whether a time traveller would cease to exist if he went back in time to kill his grandfather when he was young.
Prof Shoshany added: “In physics, a paradox is not an event that can actually happen — it is a purely theoretical concept that points towards an inconsistency in the theory itself.