For years, humans have fantasised about travelling through time, either to take a glimpse of the future or analyse the past that brought us to where we are, our failures and our successes. Although the time that has passed is considered definite, physicists have been speculating whether it is plausible for humans to travel forward in time. For example, Professor Brian Cox believes time travel is possible, but if it is successful, there is the possibility of never being able to return.
Theoretically, this theory is plausible and can be explained through a medium of principles. For instance, Einstein derived the idea of Special Theory of Relativity in 1915 which is based on two principles:
It is not possible to tell which object is moving and which object is standing still, since every observer is correct in thinking that they are standing still and the rest of the universe is moving around them.
The speed of the light is the same for all observers.
This can be explained more thoroughly through a use of an experiment where a rocket is travelling at a speed near that of the speed of light. From this rocket, a laser is fired to the earth and reflected back off of a mirror. The time taken for its journey is recorded and from the perspective of the observer in the rocket, the journey would seem like a straight line.
However, an observer standing on the Earth would believe the laser to have travelled in a ‘V’ shape, differing from the original perspective. Since the speed of the light is the same for all observers, (Einstein’s second principle of the Special Theory of Relativity), the observer on the earth would witness the laser taking a longer time to travel compared to the observer in the rocket. In essence, time has ‘slowed’ down to an extent, due to the rocket travelling at a speed close to that of the speed of light. If it were to travel at the speed of light, time would appear to stop altogether for the observers in the rocket.
For those in the rocket, time would not appear to have changed speed and it would appear as if time was passing by at a normal rate. Therefore, in theory, an observer in the rocket would be travelling in a different time stream compared to that on the earth, yet neither would realise that this phenomenon is occurring.
Although it is possible to reach speeds, close to that of the speed of light, Einstein’s General Theory of Relativity has proven that it is not possible to actually obtain it. This has been proven by the infamous formula, near enough synonymous with Einstein’s name: E= MC2
As an object increases its speed, it begins to gain mass and as it approaches the speed of light, its mass increases by a significant amount, so much so that an infinite amount of energy would be required to increase its speed by a small fraction.
With the ever-evolving technological advances that are occurring, it is plausible to believe a rocket can be designed that may reach a speed close to that of 299, 792, 458 m/s – the speed of light. Considering the passengers of the ship would be on a slower time stream compared to those on earth, a minute on the rocket could equate to a year on earth.
The following idea was mentioned internationally between physicists: a railway that is positioned circulating the earth that could pave the route for a train that will continue to gain speed to the highest value possible. A passenger on this train could travel on it for a few weeks and return to earth to find years have passed. In essence, it would be possible to catch a glimpse of the future. Although due to the restrictions of the laws of physics, the time traveller would indeed be stranded in this new time stream. Thus, the question become this: If theoretically we can travel through time, how much longer will we wait before this becomes an actuality and indeed, what are the implications?