Time is a concept that depends totally on our perceptions and the comparison we make between our perceptions. For example, at this moment you are reading this article. Suppose that, before reading this article, you were eating something in the kitchen. You think that there is a period between the time when you were eating in the kitchen and this moment, and you call it "time". In fact, the moment you were eating in the kitchen is a piece of information in your memory, and you compare this moment with the information in your memory and call it time. If you do not make this comparison, the concept of time disappears and the only moment that exists for you will be the present moment.
Renowned physicist Julian Barbour defines time in this way:
"Time is nothing but a measure of the changing positions of objects. A pendulum swings, the hands on a clock advance." 
In short, time is composed of a few pieces of information hidden as a memory in the brain; it arises from the comparison of images. If a person did not have a memory, that person would live only in the present moment; his brain would not be able to make these interpretations and therefore, he would not have any perception of time.
Today it has been scientifically accepted that time is a concept that arises from our making a definite sequential arrangement among movements and changes. We will try to make this clearer by giving examples from those thinkers and scientists who have established this view. The physicist Julian Barbour caused a great stir in the scientific world with his book entitled The End of Time in which he examined the ideas of timelessness and eternity. In an interview with Barbour, he said that any idea we have of time being absolute is false, and that research done in modern physics has confirmed this.
Time is not absolute; it is a variously perceived, subjective concept depending on events. François Jacob, thinker, Nobel laureate and famous professor of genetics, in his book entitled Le Jeu des Possibles (The Possible and the Actual) says this about the possibility that time can move backwards:
Films played backwards make it possible for us to imagine a world in which time flows backwards. A world in which milk separates itself from the coffee and jumps out of the cup to reach the milk-pan; a world in which light rays are emitted from the walls to be collected in a trap (gravity center) instead of gushing out from a light source; a world in which a stone slopes to the palm of a man by the astonishing cooperation of innumerable drops of water which enable the stone to jump out of water. Yet, in such a world in which time has such opposite features, the processes of our brain and the way our memory compiles information, would similarly be functioning backwards. The same is true for the past and future and the world will appear to us exactly as it currently appears. 
Because our brain works by arranging things in a sequence, we do not believe that the world works as described above; we think that time always moves forward. However, this is a decision our brain makes and is therefore totally relative. If the information in our brains were arranged like a film being projected backwards, time would be for us like a film being projected backwards. In this situation, we would start to perceive that the past was the future and the future was the past and we would experience life in a way totally opposite to that we do now.
The fact that time is a perception was proved by the greatest physicist of the 20th century, Albert Einstein, in his "General Theory of Relativity". In his book, The Universe and Dr. Einstein, Lincoln Barnett says this:
"Along with absolute space, Einstein discarded the concept of absolute time – of a steady, unvarying inexorable universal time flow, streaming from the infinite past to the infinite future. Much of the obscurity that has surrounded the Theory of Relativity stems from man's reluctance to recognize that sense of time, like sense of color, is a form of perception. Just as space is simply a possible order of material objects, so time is simply a possible order of events. The subjectivity of time is best explained in Einstein's own words. "The experiences of an individual" he says, "appear to us arranged in a series of events; in this series the single events which we remember appear to be ordered according to the criterion of 'earlier' and 'later'. There exists, therefore, for the individual an I-time, or subjective time. This in itself is not measurable. I can, indeed, associate numbers with the events, in such a way that a greater number is associated with the later event than with an earlier one." 
From these words of Einstein, we can understand that the idea that time moves forward is totally a conditioned response. Einstein scientifically established the following fact in his "General Theory of Relativity": The rate at which time passes changes according to the speed of a body and its distance from the center of gravity. If the speed increases, time decreases, contracts, moves slower and seems that the point of inertia approaches.
The Relativity Of Time Explains The Reality Of Fate
As we see from the account of the relativity of time, time is not a concrete concept, but one that varies depending on perceptions. For example, a space of time conceived by us as millions of years long is one moment in God's sight. A period of 50 thousand years for us is only a day for Gabriel and the angels. This reality is very important for an understanding of the idea of fate.
Fate is the idea that God creates every single event, past, present, and future in "a single moment". This means that every event, from the creation of the universe until doomsday, has already occurred and ended in God's sight. A significant number of people cannot grasp the reality of fate. They cannot understand how God can know events that have not yet happened, or how past and future events have already happened in God's sight. From our point of view, things that have not happened are events that have not occurred. This is because we live our lives in relation to the time that God has created, and we could not know anything without the information in our memories. Because we dwell in the testing place of this world, God has not given us memories of the things we call "future" events.
Consequently, we cannot know what the future holds. But God is not bound to time or space; it is He who has already created all these things from nothing. For this reason, past, present and future are all the same to God. From His point of view, everything has already occurred; He does not need to wait to see the result of an action. The beginning and the end of an event are both experienced in His sight in a single moment. Besides, for God there is no such thing as remembering the past; past and future are always present to God; everything exists in the same moment.
If we think of our life as a filmstrip, we watch it as if we were viewing a videocassette with no possibility to speed up the film. But God sees the whole film all at once at the same moment; it is He who created it and determined all its details. As we are able to see the beginning, middle and end of a ruler all at once, so God encompasses in one moment, from beginning to end, the time to which we are subject. However, human beings experience these events only when the time comes to witness the fate that God has created for them. This is the way it is for the fates of everyone in the world.
The lives of everyone who has ever been created and whoever will be created, in this world and the next, are present in the sight of God in all their details. The fates of all living things—planets, plants and things—are written together with the fates of millions of human beings in God's eternal memory. They will remain written without being lost or diminished. The reality of fate is one of the manifestations of God's eternal greatness, power and might. This is why He is called the Preserver (al-Hafiz).
 From Here to Eternity", Discover, December 2000, p.54
 François Jacob, Le Jeu des Possibles, p. 111
 Lincoln Barnett, The Universe and Dr. Einstein, p. 52-53