Look around, and you will see how time governs everything around us. On a cosmic timeline we mark events, when we have to wake up, eat, sleep, a day is over, monsoon arrives, a new year begins and a millennia ends. For long, we have considered time in three distinguishable phases i.e. past, present and the future with 2 simple rules that we can’t change the past and can’t predict the exact future. We experience time as a river; always flowing in one direction. But what if we are wrong? What if Time is like a frozen sea where past, present and future exist all together? Well, let’s try to figure it out.
Human civilization has always looked for ways to accurately measure time. The standard way to measure time is by looking at the naturally occurring repetitions and cyclic events like sunrise and sunset, full moons, constellation and movements. But in the last one century, we have achieved a precision of almost a billionth of a second by observing atoms. Yeah, we can measure time almost up to a billionth of a second. But no matter how accurate clocks are, they are unable to tell what time itself is. What is it that we actually measure? And yet if we remove the concept of time and its measurement, the world will collapse.
Now let’s see what modern physics has to say about time. During the early 2oth century, Albert Einstein proposed Time as one of the dimensions of a 4-Dimensional framework of the Universe called Space-Time. We used to believe that time is the same for everyone, everywhere at the same rate, but Einstein’s groundbreaking idea changed everything. He realized that time can run at different rates for different individuals depending on the speed they are moving and the surrounding mass. He believed that more you have of one (time-speed) less you have of other. Even if you don’t move in 3-Dimension, you always move through time. But when you move through space it affects the passage of time for you, and once you reach the speed of light, time stops. With this concept in mind and without going deep into underlying mathematics we can say what whatever we observe as time is in reality just a slice from cosmic timeline where everything that ever happened or will happen is already out there. We still see stars as they were 14 billion years ago, and they are probably already dead. We still see supernovae which exploded almost millions of years in past. So you see the concept of time mainly depends on where we are in space-time and how fast we are moving.
In simpler words, the difference between past, present and future is mere an illusion. Time itself is like a video made up of infinite frames. And it’s only when you move forward frame by frame, the concept of past, present and future comes into existence. NOW, here comes the similarity between our Universe and a simulation. You can easily compare this model of time with any form of computer simulation, video or video games and the likes. The characters or elements of these simulations will always experience time as if it’s flowing in one direction. Their perception of time will be exactly the way we perceive time, but we know their perception is WRONG. We, those who are outside these simulations, can always forward, backward, pause or stop it any moment and the people inside it may never realize. For those who are inside, time is as much of a mystery as it is for us. Even they will try to define their short existence as Past, Present and Future. 
Maybe if within those simulations, there is someone like Einstein who leads them to see time as a fourth dimension, would that make them wrong?
Probably we will never know for sure. Probably time is really like a frozen ocean where all our existence exist together.
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