Time travel- something that is seen in sci-fi and futuristic media all over the world. From Doctor Who to Back to the Future, it has always been something that has captured our attention and made us want to know if it can ever be possible in reality? The probability of this is currently being investigated by academics across different universities as part of an international research programme. Whilst there is no TARDIS as of yet, the research has opened up a flurry of questions regarding just how much we can manipulate the laws of physics and the nature and philosophy of reality itself.
On one hand, time travel can be perceived as a complete impossibility. To enable time travel to occur whilst also retaining the laws of physics, you would need to be able to travel at the speed of light. The faster something travels the more mass it has; therefore it would take an infinite amount of energy to move anything larger than a photon (a light particle). Another classic argument against time travel is known as the ‘grandfather paradox’. This states that if someone could go back in time and accidentally kill their own grandfather, it becomes impossible for the time traveller to be born, and if they were never born they could never go back and time travel becomes impossible. Therefore, if we do find a way to make it happen, the knowledge will get erased and no one in society will be any the wiser. This is also reinforced by the fact that if time travel was going to happen, why haven’t we met the future humans coming back in time?
However, whilst the likelihood of time travel might be extremely small, it can be argued that it may not be impossible in years to come. To do this, it is suggested by researchers that we think about time as a kind of portal, where someone could travel through from one point in space-time to another. In physics, this can be described as a wormhole, which is essentially a short-cut through time-space. It is much like a tunnel with two ends; each in separate points in space-time which you could theoretically and enter at one point and then re-emerge somewhere else. Researchers have no observational evidence for wormholes, but the equations of the theory of general relativity correlate with their existence. From this, researchers have described that time travel would occur “in some exotic region of the universe… [and] it’s not so much inventing a time machine as discovering a location” for it to occur. In this case, the chances of finding a suitable location that would abide by the laws of physics are so small, it is almost impossible.
The idea of time travel has sparked much debate in the scientific and wider societies. The grandfather paradox- which seems to be a primary reason that time travel will not occur- is thought to have been resolved as recently as this year, when a group of scientists have simulated how time-travelling photons may behave. This recent development suggests that-at the quantum level at least- the paradox could be resolved. From a philosophical perspective, it has also been argued that there may be a way to prevent the self-erasing process by endlessly preventing time travellers from killing- the gun may jam or the wrong target may be selected, for example. However, whilst this is a novel idea, it would be extremely difficult to develop the technology needed with so many unknowns. Another theory in place that would prevent people disrupting their original timeline is the “many worlds” theory. This suggests that we are only one version of reality and that there is an infinite number of other decisions and possibilities are happening in parallel universes. It is thought that if a time traveller makes changes, they will play out in a parallel universe and not disrupt and effect the original timeline/ course of history.
Overall, it is clear that- if time travel could ever be possible- it won’t be around for a very long time. Whilst there are potential explanations to account for some of the paradoxes, the laws of physics, the chances of wormholes being found, and the energy requirements for time travel currently render it impossible. However, the fascination with time travel and the plentiful research into it reflects just how fascinated we are with the opportunity to see history and the future for ourselves. Time is tied to everything we do, from birth to death to the origin of the universe, and the chance that we may be able to manipulate it in the future and become Time Lords ourselves will spark interest for years to come.