Time travel has been puzzling the human mind for ages. You can find hints and related concepts in writings and stories as far back in time as the Indian Mahabharata and the Greek myth of Oedipus. One could say that it is as old as the idea of “God”. It is a fascinating idea, since the irreversibility of time is pointing out directly to our mortal nature. We are all going in the some direction, all beginnings are signaling the presence of an end somewhere down the road of time.
But nowadays the approach to it is more scientific. Ever since the discrete nature of the universe has been unveiled, our approach to the usually unthinkable has changed. And time travel is part of that unthinkable. Some of us might think it is possible, but even that thought is more of a doubt related to the current scientific knowledge. There is no definite yes, or definite no.
Let us see this coming from a more scientific and less philosophic point of view. First and foremost argument that one could bring is the relativity theory. The general relativity theory leaves a number of open questions relating to the subjects. There are some geometries where the usual causality chain could be broken and the travel backwards in time is possible. One has to keep in mind that the general relativity theory, relating to the gravitational field and the way it is propagated is in essence a macroscopic law. It predicts accurately phenomena for the large bodies in the universe, even though some of the consequences in the micro-world are valid. But the theory itself is not applicable in the micro world. This is one of today’s big scientific pursuits, the unification of the forces. It is the motivation behind the pure theoretical string theory which lies on the edge of both physics and philosophical mathematics. It is the reason the Large Hadron Collider has been built in order to find the so called “God” particle which wouls explain the concept of mass and therefore make a link between the macroscopic gravity and the other 3 forces in the universe (strong nuclear force, electro-magnetic force and weak nuclear force).
On the other hand, the micro universe tells us that time travelling is possible too. Moreover there have been experiments in which matter and antimatter collisions have yielded particle duality, e.g. the same particle existed in two places simultaneously. But then again the quantum physics tells us that passing through a door might send us somewhere else, which never happens in real life (the tunneling effect). One has to understand the intrinsec statistic character of the quantum physics. Everything is possible, but not so many things are probable. And when that possibility drops to one in 10 to the power 24, the event is outright impossible, even though the mathematics might tell us something else.
This is some of the logic motivating the conception of Dr. Steven Hawking’s “chronology protection conjecture”. Even though his explanations are sometimes harder to understand due to their highly abstract character, a general look at the theory is very enlightening. And the conclusion is set to put this article in both categories: time travel is possible on very small scale (quantum scale) universe, but impossible on the large macroscopic scale in which we live.