a much smaller radius, generating an extremely strong gravitational field that even light cannot escape [5].
Time Travel By: Amy Chen
Edited By: Rekha Narasimhan Reviewed By: Brooks Park Graphic By: Eun jin Kim
T
ime travel, the concept of moving to and from different periods in time without the individual experiencing the lapse of time [1] has always been widely referenced in pop culture and literature. Movies such as A Time Traveler’s Wife and Butterfly Effect show the main characters’ ability to sporadically travel back or forward in time as well as the consequences that often ensue. Though time travel had previously been a fictitious notion deemed impossible by spectators as well as theologians alike, scientists’ close analysis of Einstein’s relativity theories and the black hole phenomenon has shown that, theoretically, time travel could exist. The first general evidence given regarding the possibility of time travel involves Einstein’s special relativity theory. There are two main principles proposed in the theory. First is the consistency of the speed of light, proven in Maxwell’s equations of electromagnetism, in which constant c represents the speed of light [2]. Second is the principle of relativity, which basically states that in essence, the laws of physics remain constant regardless of the observer [1]. Time travel in a Newtonian universe would be impossible because time and space are presented as absolute matters. However, Einstein’s special relativity proposes that since the value of the speed of light and laws of physics always remain the same, something else must change in order to keep those values constant [3]. This theory leads to the idea that the length and distance of time and motion are not fixed quantities. In contrast to the cosmos previously assumed true in the Newtonian universe, special relativity suggests a lack of simultaneity for observers of different frames of references, or inertial frames, because external time is defined within one’s own frame of reference [1]. In other words, there is no set reference frame for an inertial observer, and the value of space and time are different for every individual, depending on their own personal velocity.
Black holes are created during the end evolutionary cycle of massive stars. There are two general types of black holes: Schwarzschild, or the static and not revolving black holes with impenetrable centers; and Kerr black holes, the ones that rotate in a spiraling motion [6]. The singularities of stationary black holes are so dense and impenetrable that anything sucked in would be crushed and annihilated instantly. However, if an observer were to place himself in the singularity of a Kerr black hole, the unusual disturbance in spacetime would create a region that acts in such non-correspondence with the external time frame that the observer would possibly witness the elapse of long periods of time with little time passing by on his part. This provides another form of theoretical time travel, but restricts participants to traveling into the future [1]. Theoretically, if a fourth dimension tunnel, or “wormhole”, were to link the singularity of two rotating black holes, and remains stable enough for traversing, it would be possible for an observer to travel back in time. If one black hole could be made to move at a velocity that approaches the speed of light whereas the other remains stationary, the spiraling end of the worm hole would be progressing on a relatively slower time frame than the still end. If a traveler were to go through the stationary end and emerge from the rotating end, the individual would arrive at a time a few years prior to when he had entered. Hypothetically speaking, wormholes would serve as a connection between two points in space and time, and exist as a natural time machine. However, even if wormholes could be created naturally, which still remains disputable and highly improbable, they would be extremely unstable and collapse so quickly that no object could be sent through it. Any naturally existing wormhole would require expansion using exotic matter such as negative energy to achieve the minimum stability [1]. The forms of time travel depicted in books and movies where an individual simply steps through a portal or falls into a deep pit is indisputably simple fantasy. Einstein’s theories and the physics of black holes present the idea that time travel would not defy the laws of nature, though the scenarios in which it exists are impossible as of now. Until scientists uncover more secrets of the universe, time travel zealots will have to fulfill their curiosity with reading scientific fiction novels.
One famous example is the twin paradox; the principle suggests that if one twin were to be placed on a spaceship that’s traveling at a velocity approaching the speed of light whereas the other remains relatively stationary on earth, the effects of time dilation would show that the twin traveling at a higher velocity ages slower than the one that remains stationary, since her personal clock (or time) ticks slower as she nears the speed of light [3]. The concept of time dilation, achieved only when an object is traveling at high velocities, creates a miniscule but natural form of time travel in the Works Cited 1: Felder, G. “General Relativity” http://archive.ncsa.illinois.edu/Cyuniverse [4]. beria/NumRel/GenRelativity.html (2003) Another view on time travel concerns Einstein’s general relativity theory. Space is described as a four-dimensional plane, with time being its last dimension; and the measure of space and time is combined to make spacetime [5]. Central to the general relativity theory is the idea of a curved space. Matter in the universe generates such enormous gravitational pull that time slows when it comes within the vicinity of those gravitational fields, creating the said curvature. Time travel, therefore, could occur at regions in the universe where an enormous disturbance in spacetime is present. A black hole forms an area in space that has an even greater density than the sun but Volume 4, Issue 2. 2012
2: Hunter, J. “Time Travel [Internet Encyclopedia of Philosophy].” http://www.iep.utm.edu/timetrav/ (2004) 3: Watson, C. “Did You Know…Special Relativity” http://www.einsteinyear.org/facts/special_relativity/ (2007) 4: Nova Online. “NOVA Online | Time Travel | Think Like Einstein (2).” http://www.pbs.org/wgbh/nova/time/think03.html (2000) 5: University of Illinois. “General Relativity: Einstein: Physics.” http:// www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/gr1. html (1995) 6: Anonymous. “Black Holes.” http://burro.cwru.edu/stu/advanced/ stars_blackhole.
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