For the time we spend in this world, we make comparisons, thinking about what we did yesterday and accordingly making plans for the morrow. We think about what happened ten years ago, believe that time has passed and we have grown older. What gives rise to this belief is simply the comparisons we make between those previous moments and the present one.
If you were watching television before opening this book, you compare the time when you were watching television with the time when you are reading and imagine that time has passed between the two events. You refer to when you were watching television as “the past,” imagining there has been a passage of time between the two events. In fact, the time you were watching television is information stored in your memory. You compare “the present,” when you are reading this book, with the information in your memory, and perceive this interval as “time.” The fact is, however, that there is only the present moment in which you are living. When you make no comparison with recollections in your memory, then no concept of time remains.
The well-known physicist John Barbour makes this definition of time:
Time is nothing but a measure of the changing positions of objects. A pendulum swings, the hands on a clock advance. (Tim Folger, “From Here to Eternity,” Discover, Vol. 21 No.12, December 2000.)
ime, therefore, consists of a comparison between various perceptions that arise in the brain. A study of people suffering from the memory loss known as anterograde amnesia makes it easier to see that time is nothing more than a human perception. Such people lose all their short-term memory, they are unable to remember what happened before, and are therefore unaware whether there’s been any interval between two events. This is one further proof that time exists solely as a perception.
ince the events occurring in our daily lives are shown to us in a specific sequence, we subdivide time into the past, present and future. But in fact, the idea of a progression from the past to a future is mere conditioning. If we watched the information in our memories in the same way that we watch a film run backwards, then for us the past would be the future, and the future would be the past. This shows that time is not absolute, but forms in line with our perception.
The famous physicist Roger Penrose makes the following comment:
I think there’s always something paradoxical about the way we seem to perceive time to pass and the way physics describes time. And partly it’s a question of is there a clear temporal order of things in our perceptions, or do we somehow put lots of things together and form pictures of things . . . (http://www.fortunecity.com/emachines/e11/86/flowtime.htm)
The sequencing we perform in our own minds between events that we recall gives rise to what we refer to as past, present and future. This, however, is a decision we make of our own will. François Jacob, French biologist and Nobel laureate, makes this comparison:
Films played backward, 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 making it possible for 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.
This all goes to show that the concepts of past and future are concerned with how we perceive our memories. The truth is that we have no means of knowing how time passes or does not pass. In the same way that we can never have direct experience of the images we see, so we can never know for sure whether we are exposed to time and, if we are, how it functions, because time is merely a mode of perception.
The fact that time is a perception was confirmed with the general theory of relativity proposed by Albert Einstein. In his book The Universe and Dr. Einstein, Lincoln Barnett writes:
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 a sense of time, like sense of colour, 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.” (Lincoln Barnett, The Universe and Dr. Einstein, New York: William Sloane Associates, 1948, pp. 39-40)
In Barnett’s words, Einstein shows that “space and time are forms of intuition, which can no more be divorced from consciousness than can our concepts of colour, shape, or size.” According to the general theory of relativity, “time has no independent existence apart from the order of events by which we measure it.”
Since time is a perception, it is also a relative concept that depends on the perceiver. The speed at which time passes varies according to the reference we use to measure it. There is no natural clock in the human body to confirm the passage of time with absolute accuracy. As Lincoln Barnett has stated, “Just as there is no such thing as colour without an eye to discern it, so an instant or an hour or a day is nothing without an event to mark it.”
hen we are left in a closed room where we cannot know the time and cannot see the rising and setting of the Sun, we can never determine how fast time goes by nor how long we remain there. What makes us think a specific amount of time has gone by is nothing more than the rising and setting of the Sun and the movement of the watches on our wrists. When these are removed, anything we say about the time we imagine has passed must be conjectural and subjective—belonging to ourselves alone. For example, time goes by quickly for someone taking an exam in a limited space of time. Yet the same amount of time seems very long to that person’s friend waiting outside.
If time were an absolute reality, then it would not be a variable concept, determined by our perceptions.
According to Einstein’s general theory of relativity, the speed of time changes according to the velocity of a body and its distance from the center of gravity. As velocity rises, time contracts and is compressed, in such a way as to run slower and eventually approach the point of stopping altogether.
To use an example cited by Einstein, one of a pair of twins remains on Earth while the other heads out into outer space at a speed near that of light. When the traveling twin returns to Earth, he will find himself much younger than his brother. The reason is that time flows more slowly for the brother traveling at a high velocity.
The same example can also be considered with regard to a father traveling in a rocket moving at roughly 99% of the speed of light and his son who stays on Earth. According to Einstein, if the father was 27 years old when he set out and his son three, when the father comes back to the Earth 30 years later (in Earth time), the son will be 33 years old, but his father will be only 30. 135
The fact that time is relative affects not only the slowing or acceleration of clocks, but the entire material system, right down to the level of subatomic particles. In an environment in which time is foreshortened, processes such as the heartbeat, cell division and the activities of the brain take place more slowly. A person is thus able to continue going about his daily life without realizing the slowing down of time.
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