The first thought that hits a considerable number of individuals’ minds when the phrase “time travel” is mentioned is its derivation from science fiction movies. Back to the Future, Terminator, Stargate, The Time Machine and many others have a variety of time travel mechanisms, which in this case refer to the movement through times; either from the past to the future or in reverse. However, none of the concepts shown in these features is alike, which brings up the question of what time travel is. People have formulated varied definitions of the notion, ranging from the simple explanation of the Oxford dictionary where the term is portrayed as a fictional scientific concept of matter traveling to the past or the future, to a complicated version presented by David Lewis (Wittenberg 68). Given the amplitude of interpretations of the subject and how hard it is to prove its existence without encountering contradictions, one can argue that the true identity of time travel is unknown.
Discussion. Time travel is known to be a science fiction term providing a view on how the laws of physics can be altered to change the linear nature of time. According to Brennan, “time is linear in its entity and can only move forward, meaning what is unknown about it lies in the future but not in the past” (45). However, there has been much discussion about “changing the hands of time”; it amounts to one moving to the past from the future, which leads to the notion of time travel. The phenomenon of going back in time has been a widely debated matter, but three notable perceptions stand out among the rest, and they are as follows.
Over the years, much has been said about “time” being yet another dimension of the universe, and in this regard, the idea of time travel has also been a topic of vast controversy. According to Born, “in order to understand the time travel concept, one has to know what time is” (45). Time, as known to many, is represented through seconds, minutes, hours and so forth; however, this is not a shared notion in the scientific world. Einstein, Robert, and Roger claim that “time is the fourth dimension of the universe, along with the up-down, right-left and backward-forward dimensions” (73). In reference to the above explanation, the definition of time travel as a notion of matter moving through time can be suggested to be true. Einstein’s theory states that as an object moves at a high speed, time seems to slow down, and according to some scientific minds, in a case where an object can be sent beyond the speed of light, time travel might be a possibility (Brennan 25). In this reference, one can say that time travel has never been achieved on the principle that no device has been able to send matter beyond the speed of light.
Before disputing the concept, time travel has only one direction: from the present to the past; however, it can be argued that the contraption or time machine would have to maintain a constant speed above the velocity of light to allow matter settle at a distant past. When one speaks of high speed, they relate the issue to aerodynamics and space; this would mean the time machine would have to be operated in space from gravity as well as in a straight line; a condition that is hard to attain. Another weakness of this theory can be explained using the Terminal velocity paradox; when an object falls from the sky and is pulled by gravity, it reaches terminal velocity, which is the point where extra power or thrust is needed to propel it further than natural cause. Considering that no being has ever traveled faster than the speed of light, it is still virtually unknown of what amount of thrust is needed and how much will be required to overshoot this speed to cause a time traveling singularity.
David Lewis’ Theory
David Lewis explains time travel as a temporary suspension between departure and appearance that does not equal the period of the journey. This would suggest that time travel is rather a basis of the mind than physical nature, which could be interpreted as if most individuals have traveled through time when they shifted to a mode of transport that is faster than their previous means (Bertolami and Francisco 25). For example, when one uses a bullet train that reaches the rate of 400 kilometers per hour to cover a distance they passed over by car at the speed of 150kph, it could be said that they have time traveled because they will reach their destination in a period not equal to the journey. David’s whole concept is based on perception and time over distance traveled.
The biggest flaw of this theory is that the notion of time travel is taken from modern physics, which would change Lewis’ philosophy to accommodate the thought of arrival happening with a delay before departure. Individuals familiar with the phenomenon of special relativity may not be satisfied with his explanation, considering it does not have a clear elaboration of ”temporal separation between arrival and departure”. According to Gleick, “the relativity of simultaneity in reference to temporal separation is based on time and events, but not as explained by Dr. Lewis” (67). Owing to the relativity of simultaneity, participants in relative motion will largely refute the idea of a postponement between events. Nonetheless, this can be solved by stating temporal separation at the greatest value measured by anyone involved in a time travel event. This would suggest that if one was waiting on the arrival platform of the bullet train and saw their associate earlier than expected, they would have the notion of time travel. This would then suggest a corresponding to the accurate time lapse with a geodesic factor linking the two events.
Black Holes. One of the weaknesses in Einstein’s theory is that though experiments have been carried out to show that time does move slower when objects accelerate, there has never been a contraption that has been developed to reach the speed of approximately 300,000,000 meters per second. Other scientists along with Stephen Hawking believe that time travel is independent of machines and is a natural phenomenon. This includes rotating black holes, wormholes, cosmic strings.
According to Prof. Hawking and other like-minded specialists, when stars are nearly three times the size of the sun, they finally reach their lifespan and collapse under their own weight, causing an implosion that would create a black hole (Everett and Thomas 127). This phenomenon would provoke a sucking event that is so strong even light cannot escape it. Any matter that is close to the black hole would move faster than the speed of light and therefore, time travel. However, this theory has a blank side; matter would be crushed by infinite gravitational force that is formed at the center of the black hole. Nonetheless, in 1963, Prof. Roy Kerr stated that “some black holes after collapsing would do so in a spiral, consequently forming rotating black holes which have much more stable centrifugal force to prevent the formation of a singularity as well as reducing the gravitational force at the center, hence allowing matter to travel back in time” (128).
The biggest issue about time is that its relativity has evidence other than the information on the clock or the days on a calendar. All living beings have evidence of time as a singular effect in the form of aging bodies, structures weathering as well as crumbling and plants growing. Consequently, the idea of time travel would suggest a lack of aging or loose of time itself. A young boy receiving a picture from an older version of himself can be an example of this paradox; if throughout his life, he saves enough money to buy a time machine and uses it to go to the past, this will create a never-ending loop of non-linear time. This would mean that time travel is only but a science fiction phenomenon.
Much of the understanding of time travel is assumed from science fiction movies; the concept is demonstrated differently in the variety of Hollywood products. The same perception is carried to what scientists explain to be time travel. This paper centered its discussion on three theories, the first being Einstein’s Special Theory of Relativity that suggests that as an object moves fast towards the speed of light, time slows down, and if it were ever possible for matter to be taken beyond the velocity of 300,000,000 meters per second, then time travel would be achieved. The drawback of this course of thinking is the fact that although time decelerates on objects that locomote at high speed, the concept of reverse time after reaching the speed of light might not be relative to space, meaning one may not be able to go back to the past. The second theory presented by David Lewis states that time travel is a phenomenon of the mind that is derived when the time taken from departure to arrival does not have the same value as the journey. It is disapproved by scientists who have the understanding of the idea of temporal separation.
Bertolami, Orfeu, and Lobo, Francisco S. N. “Time and Causation.” arXiv:0902.0559, 2009.
Born, Max. Einstein’s Theory of Relativity. Forgotten Books, 2010.
Brennan, James Herbert. Time Travel: A New Perspective. Llewellyn Publications, 1997.
Einstein, Albert, Lawson, Robert W., and Penrose, Roger. Relativity: The Special and the General Theory. Folio Society, 2004.
Everett, Allen, and Roman, Thomas. Time Travel and Warp Drives: A Scientific Guide to Shortcuts Through Time and Space. The University of Chicago Press, 2012.
Gleick, James. Time Travel: A History. Pantheon, 2016.
Wittenberg, David. Time Travel: The Popular Philosophy of Narrative. Fordham University Press, 2013.