The Story Of Time
“Once upon a time” the magical phrase used at the beginning of every story. But what actually is the story of time? We say time is money, we waste time and we kill time. But do we really know what time is?
Our whole world is governed by the time. We know that time is everywhere. We know time is universal and eternal. We know it is unidirectional, flows in one direction towards the future. But how can we be so sure about time? The discoveries from the last century showed us that what we know about time may not be totally true. What if the time that we defined as universal is nothing than a stubborn illusion? If you see, the theory of time keeps changing with the passage of time. If we look during the 17th century, the grandfather of modern physics, Sir Isaac Newton, came up with the theory and pronounced that time is universal. It is an absolute unit. It is same for the people on Earth and for the people travelling across the universe. But this theory proved wrong by the Albert Einstein during the early 20th century. In 1905, Einstein published his papers on special relativity that made everyone think about time in a completely new way. He claimed that time is relative. It is not absolute rather it changes, depending on the relative speed. Imagine for a minute, a spacecraft is travelling in a space at a rate closer to the speed of light. So, according to the special relativity, flow of time would depend upon whether you are on board or you are living on Earth. So for the people inside the spacecraft travelling in space, time would run slower as compared to the time on Earth. That’s because, according to Einstein, time runs slower for the object in motion. In other words, time can vary. It’s all depend on speed. So the question is, why don’t we ever experience this in our everyday life? Well, the impact of our motion on time is so tiny that we don’t experience it in our daily life but the effect is real.
Surprisingly, our understanding of time comes from our day to day experience. And it is for this reason we are cling to another assumption about time that it never stops. It keeps flowing constantly towards the future. If we dig a little deep to understand the true nature of time, we would come to know that, it’s not only the speed of the object that affects the flow of time. In the second theory of Albert Einstein, Theory of General Relativity, he explained that gravitational force also plays an important role in controlling the time. According to this theory, very high gravitational force slows down the time in a similar way to moving at a very high speed. And when we talk about high gravitational force, there is nothing in the whole universe where you could find very intense gravity than the Black Holes. Its gravity is so much strong that it can easily eat light and it will not even burp. Let’s take a scenario here to understand the effect of intense gravitational force on time, two person are standing on the edge of a black hole. Now one of them falls inside a black hole, so now the person standing on the edge of a black hole would notice that time, for the person inside a black hole, is beginning to slow down as he goes more and more towards the center of it. And as soon as he reaches the very center of it, where the gravitational force is infinite, time would stop altogether. There is no more tick tock of the clock at the center of a black hole. But for the person standing outside of it, time keeps running at a normal rate. And that means time can be still too.
So far we have understood that, time slows down if you travel close to the speed of light. Time stops if you travel at the speed of light. So by this we can also conclude that, if you exceed the speed of light, time would run backwards. So in order to travel to the past, go on. You know what to do.