Time Travel Is An Elusive Phenomenon
Time travel is an elusive phenomenon in which a person or thing has the ability to go back and forth to a particular timeline. The idea of time travel can be traced back to Hindu Mythology in which King Raivata Kakudmi goes to heaven to meet his creator and comes back to see that great time has passed. Time travel has been studied and theorized by many scientists, such as Albert Einstein and Stephen Hawking, leading to many competing concepts. Time travel is topic that can be interpreted in many different ways with respect to each given theory of the universe such as General Relativity and Quantum Mechanics. Even with an assumption of the possibility of time travel, many scientist and philosophers have discovered loopholes or paradoxes.
Despite the many theories surrounding time travel, many people remain skeptical of the possibility of time travel. Some scientists theorize that even if time travel were possible, any human attempt at time travel would be fatal. Furthermore, the controversy of time travel has been seen in popular mainstream films and television shows such as “Star Trek,” “Back to the Future,” and “Doctor Who” in which characters travel back and forth in time. For example in the “Back to the Future” series, the main character Marty McFly goes back in time to fix some of the problems that are plaguing his time. When he returns after fixing the root of the problem, he realizes that a lot key things in his time period have significantly changed for the worst. He then has to go back in time to fix the mistake of going back in time and trying the change the past. Another example can be witnessed in “Doctor Who,” in which characters go inside of a time machine disguised as a police box called a TARDIS. Time travel is very notable in not just science-fiction books but also in books general such as “A Christmas Carol”. In this book the spirit of the main character comes back in time to tell his former self to change and become a nicer and better man so that he doesn’t send up like his future self.
Scientists believe that time travel is a possibility in the context of the theory of General Relativity. General Relativity describes space-time as having two distinct commodities: the three dimensional object world and time. Time in General Relativity is relative to mass and velocity. A person traveling at the speed of light will age slower compared to someone not traveling at the speed of light. Time travel in general relativity is possible when particular spacetime geometries allow traveling faster than light. Some instances of these spacetime geometries are cosmic strings, Alcubierre drive, and traversable wormholes. Faster than light communication occurs when particles that have zero rest mass travel faster than the speed of light. Stephen Hawking has proposed the idea of chronology protection conjecture in which time travel is mathematically existent in closed timelike curves. Stephen Hawking, however, determined that the pileup of vacuum fluctuations caused by such anomalies would destroy any type of time machine from being created.
A possibility of time travel can occur with wormholes that are permitted by the Einstein field equations of general relativity. In this case, one end of the wormhole would have to be moved within the gravitational field of an object that has a higher gravity than the alternative end. Time dilations causes one of the ends to have “aged less”. This means that a person entering the “younger” side would exit the “older” side as the same age of that of the “younger” side. This effectively means that for a person watching this from the outside, the individual entering the wormhole goes back in time. This method, rather than becoming the device in which people can travel through time, makes the pathway through which people can travel back through time. This method would not allow new technologies to pass through, however. The creation of a wormhole, in this case, is the difficult part because to create a wormhole there needs to be a substance in existence that contains or is made up of negative energy. The amount of negative energy required, however, is debated among scientists who calculate the necessity of the negative energy to be very small while others require it to be extremely large.
Even though traveling back in time might seem like a distant possibility, traveling forward in time can be explained quite simply by the theory of general relativity. The theory of relativity explains how if a object is traveling near or at the speed of light, the object becomes invariant to an outside observer. When the object becomes invariant it remains the same. An individual in this case might use this invariance to make time move much slower on his side versus somewhere else in the universe. This effect can also be achieved by gravity. This allows the individual that is invariant to age slower or “travel forward in the time”. This method would only allow the individual to travel forward in time not backwards even into his own time period. This type of time dilation has been in practically used in satellites, where the satellites have to be calibrated to run a little slower than that of earth because the satellites experience a smaller gravitational force which increases the rate of clocks ticking with respect to clocks on the surface of earth.
Despite the fact that much of time travel is based around the theory of General Relativity, Igor Dmitriyevich Novikov, a Russian theoretical astrophysicist, speculated that when quantum mechanics are considered self-consisted solutions would be present in every time machine configuration. Building off this interpretation of quantum mechanics, the many-worlds interpretation was created. This interpretation basically states that there are an infinite number of universes in which everything that could have possibly happened in the past did happen or did not happen. In other words, this interpretation implies that in each of the infinite universes, something is different.
Before this interpretation, reality was seen as a single unfolding history, however, this new interpretation saw reality as a many-branched tree in which each different branch represents an alternate universe where every single possible quantum outcome has occurred. The many-worlds interpretation has been seen in stories such as “Star Trek,” “Star Maker,” and most recently, “Rick and Morty.” In the show “Rick and Morty,” the many-worlds interpretation is the basis to the entire plot with one of the protagonists, Rick, constantly warping from different timelines and universes while battling new troubles from each of these different universes. The two main protagonists, Rick and Morty, sometimes run into trouble when they change too much from the past, which is evident of the ripple effect.
The ripple effect is a change of the future timeline due to changes from the present or past. This effect essentially means that if someone were to change something from the past, the future would be heavily altered by the change. The ripple effect is further highlighted when examining another effect known as the butterfly effect. The butterfly effect essentially states that seemingly small changes in the past create much larger changes to the future and present. The butterfly effect was first examined in weather before eventually being used in quantum mechanics. This effect was used when describing a metaphorical affect a butterfly flapping its’ wings might have on a future tornado. This metaphorical phrase refers to the idea that by flapping its’ wings a butterfly would alter the atmosphere which would in turn change the size or direction of a tornado.
Time travel is only possible when spacetime is warped in a specific manner, which decreases the likelihood by a great margin. My scientists and philosophers have also preached the idea of time travel not being a possibility by arguing that if time travel was possible in the future, then why haven’t the “tourists from the future” populated the present or the pass. People have even tried to entice the travelers to meet up to prove the existence of time travel. There have been numerous events such as Perth’s Destination Day or even MIT’s Time Traveler Convention. There has also been a convention in 1982 by people who proclaimed themselves as the “Krononauts”. None of these experiments have been successful which further fuels the argument made by scientists, such as Stephen Hawking, that are skeptical about the possibility of time travel.
Even with the assumption of the possibility of time travel many questions and objections are put forth. One these objections is commonly known as the grandfather paradox. In this scenario, an individual with a hypothetical time machine goes back in time to kill his grandfather before his (the individual’s) dad was born. This would cause the individual’s dad to have never been born which would have caused the individual to not be born either. Since the individual is not born he cannot go back in time to kill his grandfather which means that his (the individual’s) father is born which means the individual is born. This creates an endless contradicting loop. The Novikov self-consistency principle solves this problem by claiming that actions taken by time travel cannot physically change the past, but rather lead to the same future through different means.