Data Bases • Custom Term Papers • Free Term Papers • Free Research Papers • Free Essays • Free Book Reports • Plagiarism? Links • Top 100 Term Paper Sites • Top 25 Essay Sites • Top 50 Essay Sites • Search 97,000 Papers @ DirectEssays.com • Search 101,000 Papers @ ExampleEssays.com • Search 90,000 Papers @ MegaEssays.com Free Essays • Term Paper Sites • Chuck III's Free Essays • Free College Essays • TermPaperSites.com • My Term Papers • Get Free Essays • Essay World • Planet Papers	Search Lots of Essays Back to Subjects - Physics time travel time travel For many years time travel was the stuff of science fiction. This was all just part of the world’s imagination until recently. Scientists now believe that the current laws of physics allow us to travel through time. They believe that we can now travel back to see our founding fathers sign the Declaration of Independence. We could travel to 2999 to witness the birth of the next new millennium. Such travel would require a machine capable of withstanding great pressures and incredible amounts of speed. The act of actually traveling through time is, for the most part, agreed upon, but the implications of such travel are not so decided upon. Many different theorists have different views of what could happen and some go as far as to say that if we did travel to the past, we would end up in a different universe that is a replica of this one. One of the most basic concepts is that of dilation, a stretching of something. Some scientists believe that the main gateway to the past or future is a wormhole. Einstein’s general relativity theory explains about universal constants. This is important to understand the concepts of travel at light speed. Traveling to the past could create problems if someone tried to change something. This is a paradox. A few of these paradoxes are explained through the use of quantum mechanics. Imagine sailing though the cosmos at the speed of light with no time passing us by, moving throughout time to witness the ancient Egyptians create their masterpieces and the great brachiosaurs give birth to a big baby. This consept of time travel that we have only speculated about could be formulated into reality and could become as common as driving to work every day. Before the time of Einstein, Newton and other great investigators thought of space as an infinite expanse in which all things exist (Hewitt 213). We are in space and we live in it along with all of the planets and stars. It was never clear if the universe exists in space or space exists in the universe. Does space exist outside the universe or only within the bounds of it? The similar question, does the universe exist only in time or does time only exist in the universe? Was there time before the universe, and will there be time after it ceases to exist? “Einstein’s answer to this is that time and space only exist within the universe. There is no time or space ‘outside’”(Hewitt 213). Einstein said that space and time are two separate parts of a whole called space-time (Hewitt 213). To understand this, consider our present knowledge. We know we move though time at the rate of 24 hours per day. This is only half the story, though. To get the other half we have to convert our thinking from moving though time to moving though space-time (Hewitt 213). When we move, we not only move through space, we move though time (Hewitt 213). This is the idea of space-time. If a person were to stand still, they would be moving only though time. If they moved a little, they would be moving though space a little bit, but still mostly though time. If one were to travel at the speed of light, what changes would they experience in time? The answer is simple; they would be traveling through space, with no travel though time (Hewitt 214). They would be as ageless as light, for light travels though space only (not time) and is timeless. The frame of reference of a photon, a particle of light, a trip across the universe would take no time at all (Hewitt 214). To understand how traveling though time would work, we must first understand how time and space can be stretched. Motion in space affects motion in time. Whenever we move through space, we to some degree alter our rate of motion in time. This is known as time dilation, a stretching of time that occurs ever so slightly for everyday speeds, but significantly for speeds approaching the speed of light. If we were to attempt to travel to the nearest star, Alpha Centauri, which is 4 light years away, even traveling at the speed of light would take 8 years round trip (Hewitt 228). The center of our galaxy is something like 30,000 light years away and at the speed of light would take 30,000 years to get there. We could not possibly survive that long. These arguments fail to take in to account of time dilation, though. Time for a stationary observer on earth and for an astronaut on a spaceship of high velocity is different. A person’s heart beats to the rhythm of the realm it is in. One realm of time seems the same as any other to the person in the realms, but not to an observer outside that realm that can see the difference. As an example, astronauts traveling at 99% the speed of light could make a trip to the star Procyon that is 11.4 light-years away in 23 earth years round trip (Hewitt 229). Because of time dilation, it would seem that only 3 years passed for the astronauts, their clocks would be 3 years older; they would be biologically only 3 years older (Hewitt 229). It would be the mission control people that would appear to be 23 years older. The question is why does this happen. Let’s say that we are in our hometown, looking at a grandfather clock in the center of town. The clock reads 12:00 noon. Light from the sun bounces off the face of the clock and hits our eyes. We then turn our head and the light misses us and travels off into space. In space, there is a space ship that is traveling at the speed of light. An astronaut looks out his passenger-side window and sees the reflection of the clock. It reads 12:00 noon. As he continues to move at the speed of light, he keeps up with the reflected face of the clock. In the space ship time would pass as normal, but time in the universe would have seemed to stop. This might sound like cosmic bologna but the idea has been proven. In 1975 Professor Carl Tllie of the University of Maryland tested this theory using two synchronized atomic clocks (Brian par2). One clock was placed on a plane and flown for several hours while the other clock stayed on the ground. Upon landing, the clock on the plain was a little slower than the one on the ground (Brian par3). This was not due to experimental error, for the same test was done several times and each time yielded the same results. Because of time dilation travel into the distant future is a definite possibility. The only problem lies in propelling a craft to such speed at which light travels. Carl Sagan wrote a science fiction novel about a fictional device that allowed his character to travel great distances across the universe. “Those faster than light speeds are not achievable; he also knew there was a common convention in science fiction that would allow a gimmick of a shortcut through ‘Hyper space’ as a means around this problem” (Time Travel Institute par2 ) . Sagen turned to Kip Thorne for help for hyperspace connections through space-time (Time Travel Institute par2). A black hole always has two “ends,” a property ignored by everyone except a few mathematicians until the mid-1980s (Time Travel Institute par3 ) . Thorne was sufficiently intrigued to set two of his Ph.D. students, Michael Morris and Ulvi Yurtsever, the task of working out some of the details of the physical behavior of what the relativists know as “wormholes” (Time Travel Institute par3 ). By starting out from the mathematical end of the problem, they constructed a space-time geometry that matched Sagan’s requirement of a wormhole that could be physical traversed by human beings. Sagan was right; hyperspace connections do at least in theory provide a means to travel to far distant regions of the universe without spending thousands of years putting around in an ordinary spacecraft(Time Travel Institute par3 ). Since the 30’s scientists have speculated that wormholes exist. Einstein’s theory combines three-dimensional space with time to create a four-dimensional space (Brian par3). Wormholes are gateways between two different parts of the universe made by linking two black holes. Wormholes are in the fabric of four-dimensional space that are connected, but which originate at different points in space and different times (Brian par3). By connecting the two holes they provide a quick path between two different locations in space and time. Distortions in space cause the point separated by the gap to bulge out and connect. This forms a wormhole through which something could instantaneously travel to a far away place and time. This is basically the 4 dimensional equivalent of folding sheet of paper, to make contact from one edge of the paper to the other. One could build a craft strong enough to withstand the intense force of the gravity towards the center and pass right through like opening a door of a house and stepping outside, except the space travelers outside could be light-years away and centuries before the current time. If the traveler enters one side he would exit in the opposite side in a different place and time. The difficulty of doing this is in keeping the hole open till the travel gets through otherwise it would collapse and the traveler would not be seen again. The trip is not impossible, just extremely difficult. It is believed to be possible to create our own wormhole. To actually make one, two identical machines consisting of 2 parallel metal plates charged with unbelievable amounts of energy would need to be constructed (Relativity 1). When the machines are placed in close proximity of each other the enormous amounts of energy, about that of an exploding star, would rip a hole in the space-time continuum and connect the two machines via a wormhole (Relativity 1). This is possible and the beginnings of it have been illustrated in the lab by what is known as the Casimir effect (Relativity 3). The next step would be to put one of these machines on a space ship and send it off at near light speed. The ship would take the machine on a journey while being connected to the other on earth via the wormhole (Relativity 2). A step in the hole would take us to where the other machine is, but that would be in a different time. Its use would be somewhat limited because we could not travel to a time before the machine was created (Relativity 1). However if we were to utilize wormhole technology we would have to be so advanced that we could master the energy within black hole. Space-time consists of portraits or events that represent a particular place at a particular time. Your life forms sort of a worm in space-time. The tip of the tail is your birth and the head is your death. And everything that is the body is your life, otherwise called your world line (Gribbin 1). In three-dimensional space, a rocket that is not accelerating is stationary, but in four-dimensional space the ship is moving along its world line (Gribbin 2). Einstein’s law states simply that the world line of every object is a geodesic in the continuum. A geodesic is the shortest distance between two points but in curved space is not generally a straight line (Gribbin 1). If an object’s world line were to be distorted, so much as to form a loop connected with a part on itself that represents an earlier place in time it would create a corridor to the past (Gribbin 1). Picture a loop to loop that runs into itself as it comes around. This closed loop is called a closed time-like curve. These curves could be used to travel into our own history. All the claims made about time travel are consequences of the basic scientific laws and standard quantum mechanics (Quantum 1). Wormholes and closed time-like curves appear to be the main way to travel to the past. The aforementioned theories do fine in explaining how we would go about traveling through time, but they do little to explain what it would be like traveling through wormhole or a closed time-like curve. Quantum mechanics can be used to model possible scenarios and yields the probability of each possible output (Quantum 1). In the context of time travel, it has a so-called “many universe interpretation” (Quantum 2). Huge Evertt III first posed this idea in 1957 (Quantum 2). This means that if something can physically happen it does in some universe. Everett says that our reality is only one of the many equally valid universes. There is a collection of these universes called a multiverse (Quantum 3). Every multiverse has copies of every person, structure and atom (Quantum 3). For every possible event every possible outcome is said to be played out in a different universe (Quantum 3). This interpretation of Quantum Mechanics is quite controversial, but it does suggest that it may be impossible to travel backward in it to our own dimension, but quite possible to travel back in time to an alternate dimension. So now that we know travel through time is theoretically possible, what would it be like? What would traveling at light speed be like? It would be similar to driving our car at 60 mph. You could not really tell the difference; Einstein says that you cannot tell the difference in uniformly moving vessels (Preston 3). According to Einstein’s laws of special relativity light speed travel is not achievable (Preston 3). For any object to attain light speed, an object must be mass less, such as a photon (Preston 3). Any object with mass would require an infinite amount of energy to accelerate to light speed (Preston 3). As we know, everything has mass so it would be impossible for any human to achieve these speeds. Another barrier on our traveling the speed of light is the fact that light is pure energy. If we were to travel at that speed, we would turn into energy blobs. What happens when we actually travel back in time? What happens if we change something, or try to commit suicide or to invent something from the future that we take for granted? The future from that point could be drastically changed. This argument is commonly called the “Chronology Principal” (Gribbin 6). This principal states that the time travel could bring information to the past that could be used to create new ideas or products (Gribbin 6). If Pablo Picasso, the most influential and successful painter of the 20th century were to travel back in time to meet his younger self, assuming he stayed in his correct universe, he could then give himself a portfolio of all his work. His younger self could reproduce the paintings and profoundly and irrevocably affect the future of art. Therefore the creation of those pictures would involve no creative energy by the “inventor.” The reproductions would exist because they are copies from the original and the originals exist because they are copies of the reproductions. No creative energy would ever have to be put forth to create these masterpieces. Because of the chronology principal time travel, by some, has been ruled out (Gribbin 6). The cosmos await us, and the history of our world is at our fingertips. Would we use this great power for good, bad, and wealth? All we have to do is get in our spaceship, set sail for the nearest wormhole, and hope for a little luck, and we can witness things only told in stories. Only the traveler can decided what he or she wishes to go back for. The theories today state that traveling through time is possible. However they do not say what could be the repercussions of our actions. This great frontier awaits us; we have the knowledge, and are slowly but surly developing the technology. Only time will tell when time itself no longer governs our lives as one of the chief amendments of the universal constitution. Bibliography: Works Cited. Preston, Steve. “Time Travel” http://freespace.virgin.net/steve.preston/time.html 5 December 2001. Preston, Steve. “Basic Introduction to time travel.” http://freespace.virgin.net/steve.preston/time1.html 5 December 2001 Brian. Brian’s views on time travel and interdimensal voyages. http://www.iit.edu/`bosabri/time/html. 5 December 2001 Time Travel Institute. “Theory’s and Concepts.” http://www.timetravelinstitute.com/theory/ 6 December 2001 “Relativity.” http://www.time-travel.com/relativi.html 6 December 2001. “Quantum.” http://www.time-travel.com/quantum.html 7 December 2001 Gribbin, Jhon. “Hyperspace connections : Black holes, White Holes, Worm Holes.” http://www.time-travel.com/hypeconn.html 7 December 2001 Word Count: 2723
Copyright © 1998-2008 College Term Papers, INC All Rights Reserved. DMCA Notifications and Requests