INTRODUCTION
Time travel – hopping between various points in time is a very popular concept in the world of fiction for decades. Various movies and series like Back to The Future, Dark, and so much more are fully based on messing up with the timeline. In all these movies and series, we see a person getting inside a crazy looking vehicle or sometimes a device and use it to travel through time. Now the question is, ‘Have any of you ever thought is time travel possible in real life? And if so, what would be its consequences of messing up with the timeline?’. We are going to answer these questions in the forthcoming sections and also take a look into some of the theories that state time travel is possible.
WHAT IS TIME?
What is the time? Most of us think that time is a constant, while physicist Albert Einstein showed that time is an illusion; it is relative — it can vary for different observers depending on their speed through space. According to Einstein, time is the “fourth dimension.” Space is described as a three-dimensional arena, which provides a traveler with coordinates — such as length, width, and height —showing location. Time provides another coordinate — direction — although conventionally, it only moves forward. (Conversely, a new theory asserts that time is “real.”). Einstein’s theory of special relativity states that time slows down or speeds up depending on how fast someone moves relative to something else. If a person travels at the speed of light then he would age much slower than his twin at home. Also, according to Einstein’s theory of general relativity, gravity can bend time.
Consider time as a four-dimensional fabric. When anything that has mass sits on that piece of fabric, it causes a dimple or a bending of space-time. The bending of space-time causes objects to move on a curved path and this curvature of space is what we call gravity. Both the general and special relativity theories have been proven with GPS satellite technology that has very accurate timepieces on board. The effects of gravity, as well as the
satellites’ increased speed above the Earth relative to observers on the ground, make the unadjusted clocks gain 38 microseconds a day. In a sense, this effect, called time dilation, means astronauts are time travelers, as they return to Earth very, very slightly younger than their identical twins that remain on the planet.
TIME TRAVEL THEORIES
There are so many theories that state the possibility of time travel but none of it has been proven practically. According to NASA, the relativity theory also provides possibilities to travel through time, but the equations will be complicated to achieve physically. One possibility is to travel faster than light, which travels at 186,282 miles per second (299,792 kilometers per second) in a vacuum. But through Einstein’s equation, it’s said that if an object travels faster than the speed of light then it would have both length and infinite mass of 0. This appears to be physically impossible, although some scientists have extended his equations and said it might be done. While Einstein’s equation makes the concept of time travel difficult, some groups have proposed alternate solutions to jump back and forth in time.
INFINITE CYLINDER
In this theory, one would take the matter that is 10 times the sun’s mass, then roll it into a very long but very dense cylinder. After spinning this up a few billion revolutions per minute, a spaceship nearby — following a very precise spiral around this cylinder — could get itself on a “closed, time-like curve”, according to the Anderson Institute. Astronomer Frank Tipler proposed this, and this theory is also sometimes known as a Tipler Cylinder. There are also limitations with this method, and also the cylinder must be infinitely long for this method to work.
BLACK HOLES
Another possibility would be to move a ship rapidly around a black hole or to artificially create that condition with a huge, rotating structure. “Around and around they’d go, experiencing just half the time of everyone far away from the black hole. The ship and its crew would be traveling through time,” physicist Stephen Hawking wrote in the Daily Mail in 2010. “Imagine they circled the black hole for five of their years. Ten years would pass elsewhere. When they got home, everyone on Earth would have aged five years more than they had.” However, he added, the crew would need to travel around the speed of light for this to work. Physicist Amos Iron at the Technion-Israel Institute of Technology in Haifa, Israel pointed out another limitation if one used a machine: it might fall apart before being able to rotate that quickly.
PARADOXES
What if time travel is practically possible? What if we can travel back in time and change an event that says we prevent the assassination of JFK? Well, we are messing up with the timeline. A very minute change in the timeline can cause a very drastic change in the present or the future. The Sci-Fi web series and movie especially the series named Dark is fully based on this. This timeline stuffs will make us more confused so to make to precise and short there was something called paradoxes that were introduced. Paradoxes mean the controversies that occur due to messing up with the timeline. Some of the most popular time paradoxes are as follows:
Grandfather Paradox: Let’s imagine a time traveler traveling back in time and kills either his father or grandfather, what would happen? Yes, the time traveler won’t be born. So, what happens to the traveler? Does he gets disintegrated like how it happens in movies? Or surprisingly nothing happens? Well, this is the grandfather paradox.
What few scientists say is that if this happens then the person won’t be born in one parallel universe but in the other, he will while others say that the photons that make up light prefer self-consistency in timelines, which would interfere with his evil, suicidal plan by killing his generation.
Bootstrap Paradox: This is one of the simple but complicated paradoxes to understand. We all know the great pop singer and dancer Michael Jackson, what if we travel back to a point in time where Michal Jackson hasn’t become a celebrity yet and meet him and we tell him that you are popular for your music album named Thriller? Yes! He would be clueless. Now to prove yourself right what you do is you give him a copy of his album which he hasn’t even done yet. He then listens to that and shares it with the public and he earns the title King of Pop and the pop singer Michal Jackson. So, what’s the origin of the album, how did it originate, and by whom it was made? Confusing right? Yes, that’s what the bootstrap paradox is. It’s the lopping of an object in the infinite time loop without an origin in the timeline.
IS TIME TRAVEL STILL POSSIBLE?
This is a million-dollar question this world has, even though there are so many theories and all this question hasn’t been answered yet. The most common theory is traveling faster than the speed of light, but do you really think it’s possible, and also even if we travel faster than the light do you think a human can survive it? Not! Using gravity would also be deadly. To experience time dilation, one has to stand on a neutron star, but the forces a person would experience would rip you apart first. While time travel does not appear possible — at least, possible in the sense that humans would survive it — with the physics that we use today, the field is constantly changing. Advances and developments in quantum theories could provide some understanding of how to overcome time travel paradoxes. So the answer to the question will be to wait and watch until then this question remains unanswerable!