Posted: June 14th, 2019

Time Travel in Einstein’s Universe

Time Travel, it has been a greatest interest of humankind for ages. There have been multiple novels and movies about Time Travel even though there still does not have a clear way to execute it. Scientists, over the century, tried to figure out the secret of time and tried to find the way to manipulate them.
Obviously, it has not been successful since there are not any surprising news about its experiment cases that were successful, or they are not shown to the public yet. On this essay, I will examine the topic whether the Time Travel is plausible or non-plausible. Through my research, you will be able to tell that it is possible in some extend, however, it is still impossible.
In order to explore the topic of time travel, we must understand what time is. People often has a misconception about time that it is a constant, while Albert Einstein has a different explanation. Time is relative in manner of observer’s speed through space. Space, a three-dimensional arena, providing a traveler with coordinates such as length, width, and height. Time, on the other hand, provides another coordination: direction. Time only moves forward due to entropy.

Entropy is a measure of jumbled and disordered a system is. Also entropy is not symmetrical, which is called the second law of thermodynamics. Through the second law of thermodynamics, we can know that over the long run any large enough system will always increase in entropy it will change from an ordered state to a less ordered state. Because it’s a one-way process, many physicists have hypothesized that it somehow dictates the direction the arrow of time is pointing.
While traveling to the past remains on the questionable state, travelling forwards in time is surprisingly easy. Einstein’s special theory of relativity, developed in 1905, shows that time passes at different rates for people who are moving relative to one another. Although the effect only becomes large when you get close to the speed of light. So, in short, in order to travel to the future, you must achieve the speed of light. This theory is well-explored in the movie series Back to the future. Back to the Future is a 1985 American science fiction film directed by Robert Zemeckis and written by Zemeckis and Bob Gale.
It stars Michael J. Fox as teenager Marty McFly, who accidentally travels back in time to 1955, where he meets his future parents and becomes his mother’s romantic interest. Christopher Lloyd portrays the eccentric scientist Dr. Emmett “Doc” Brown, inventor of the time-traveling DeLorean, who helps Marty repair history and return to 1985. In this movie, by having plutonium to power the time machine, they achieve the speed of light and travels time forward. One possibility could be to go faster than light, which travels at 186,282 miles per second (299,792 kilometers per second) in a vacuum.
Einstein’s equations, though, show that an object at the speed of light would have both infinite mass and a length of 0. This appears to be physically impossible, although some scientists have extended his equations and said it might be done. However, since our technology still has not reached that level of inventing a time machine that could achieve speed of light, we cannot travel to the future. Therefore, Einstein’s theory on traveling in time forward is currently impossible.
Another possible hypothesis for time travel is going through a wormhole. Wormholes were first theorized in 1916, though that wasn’t what they were called at the time. While reviewing another physicist’s solution to the equations in Albert Einstein’s theory of general relativity, Austrian physicist Ludwig Flamm realized another solution was possible. He described a “white hole,” a theoretical time reversal of a black hole.
Entrances to both black and white holes could be connected by a space-time conduit. In 1935, Einstein and physicist Nathan Rosen used the theory of general relativity to elaborate on the idea, proposing the existence of “bridges” through space-time. These bridges connect two different points in space-time, theoretically creating a shortcut that could reduce travel time and distance. The shortcuts came to be called Einstein-Rosen bridges, or wormholes.
Einstein’s theory of general relativity mathematically predicts the existence of wormholes, but none have been discovered to date. A negative mass wormhole might be spotted by the way its gravity affects light that passes by. “You can go into the future or into the past using traversable wormholes,” astrophysicist Eric Davis told LiveScience. But it won’t be easy: “It would take a Herculean effort to turn a wormhole into a time machine. It’s going to be tough enough to pull off a wormhole.” (Redd 2017) In simple words, this theory is also impossible currently. 
Last theory for potential time travel involves something called cosmic strings. Narrow tubes of energy stretched across the entire length of the ever-expanding universe. These thin regions, left over from the early cosmos, are predicted to contain huge amounts of mass and therefore could warp the space-time around them. Cosmic strings are either infinite or they’re in loops, with no ends, scientists say. The approach of two such strings parallel to each other would bend space-time so vigorously and in such a particular configuration that might make time travel possible, in theory. However, this theory’s flaw is that scientists are still uncertain that it exists or not. Until they find a clue of the existence of cosmic string, this method of time travel remains impossible.
As a conclusion, there are many theories about time travel and studies of its possibilities out there in the field of science. These include Einstein’s theory of relativity, wormhole theory, and cosmic string theory…etc. However, all of them seems to be impossible and remained as a mystery for human to explore. As technology advances, those theories might become possible reality that we can have experiments on. Since nobody knows what comes in the future, we might have a possibility of traveling the mysterious time itself. Although, we must appreciate this thing called time since it is such a precious thing, we should not waste it. Our time is limited in sense of human life. To appreciate time, we should do our best to live a life without regrets.