Do you know that there are people in this world who do not have the concept of time, no watches, no calendars and no age? They live synonymous with the happenings of day and night, and the events of rainy season and dry season. They assign different names to represent their childhood, adulthood and old age and also to the positions in their society. The number system in their language ends at four. There are no concepts like “last week” or “next year”, because they don’t have the words “week”, “month” or “year”. Their traditional way of life consists of farming, fishing and hunting. These people are called Amondawa, a tribe living in the rain forests of Brazil, discovered by the British Scientists in 1986.
Definitely they are living ‘within time’, but instead of passing their time they live in a world of freedom that is controlled by events. Blessed are those people who need not rush against time to earn a living and have never told in their life with regret, ‘I don’t have time to do it’.
What is Time?
Time is a measurement of the interval between events, usually expressed in units such as second, minute or hour. The information provides the relative aspects of certain events and also a comparison between the known motion of the sun and an unknown motion of an object. We are measuring certain intervals that give us specific information such as speed of light, rhythm of our heart beat, speed of our car, our age and physical growth, and many more.
Time is formless and invisible, but it is a concept with realistic effects that are recognized throughout the universe. We are conscious about time through different aspects such as the function of clocks, motion of substances, forces, sun rise and sun set, day and night, change of seasons, movement of planets, our aging, and so on. Time can be measured using clocks or similar instruments, but it will always keep on moving ahead in the same direction even if all the clocks in the world stop functioning.
We cannot even think about a time without ‘time’. It is the most essential and convenient thing that makes our life moving. Set up in various standards, time allows managing different events in this scientific age. Earth has been divided into various time zones having reference to the time at the longitude of Greenwich in England. Coordinated Universal Time (UTC) is a universal standard that coincides with the Greenwich Time.
Unit of Time
In the International System of Units (SI), the fundamental unit of time is Seconds. One second is equal to the time interval of occurrence of 9,192,631,770 cycles of the radiation produced by the transition between two electron spin energy levels of the ground state of cesium 133 atom. Other common units used to represent time are minute, hour, mean solar day and synodic year (sun based earth year).
Measurement of Time
Sun dials were the earliest devices used to measure time which were based on the movements of sun across the sky. With the advance of technology new accurate time keeping devices were developed such as watches, clocks and varieties of digital devices, relieving time from the celestial connection. Atomic clocks are the most accurate time measuring devices used nowadays, which make use of the spin property of atoms and are capable of maintaining accuracy in seconds for millions of years.
Time Flows Continuously
We have an impression that time flows smoothly and continuously. But is it true? Why it is not possible that time advances in very small steps and produces an effect of continuous movement similar to the happening in a film? If it is so, it should be possible to analyze these smaller time segments and observe the minute footsteps of time. Scientists are successful in developing sophisticated equipment that can break down a second into its minute form called a ‘Femtosecond’ and freeze it for observing its subtle movements. Pulsating laser beams are used for this purpose. And this Femtosecond is as small as one thousands of one trillionth of a second.
It has been observed that even at this subtle level, time shows a continuous flow, without imprinting its footsteps. With subsequent experiments conducted by scientists, breaking even smaller units of time, they could not reach a level to observe the distinct steps of time, and hence we have to accept that time flows continuously.
Direction of Time Flow
We have been watching time flowing from the past to the future, through the gateway of the present. The past is living in our memory and the future is yet to come, which is unknown to us. Only thing we know is the occurrence of events one after another. The present is a very short-lived moment. Whatever is happening in the present is restrained for a very limited point of time, like the point of a needle, and immediately becomes past. We find it difficult to distinguish the present from the past. Activities of the past can be measured; they live in our memories just like a recorded tape. Future is said to be the projection of the past, but we have never seen it and it looks like a blank, unrecorded tape. But what about the present that gives us the real feeling of life? It is slipping form us in a fraction of a second, merges with the past, and remains immeasurable.
And we know the time is flowing through a specific direction, from the past to the future. But how sure we are that the time flows only in a definite direction? The laws of thermodynamics will help us to clearly understand this arrow of time.
Arrow of Time
As per the second law of thermodynamics, the entropy of the entire universe, as a closed system, will always increase over time, and the changes in entropy will never become negative.
Entropy, the thermodynamics arrow of time, is the measurement of disorder of a system. That means the disorder in the universe will always increase and can never be expected to arrange in a higher order. For example, you will always get older and never younger. An egg can be turned into an omlette, but not the other way. A new pack of cards will be in order when you first open it up. But after shuffling for a while it will be disordered and the disorder continues as time passes. But the chance of bringing it back to a perfectly ordered set by shuffling is unlikely, no matter how long you tried. This is a statistical law and is an arrow of time.
Big Bang
Cosmologists believe that about 13.7 billion years ago an event called Big Bang happened and the universe originated. It is believed that time did not exist before Big Bang. With Big Bang, the universe is created and all matter, space and time came into existence. Big Bang is known to be the ultimate arrow of time and is always positioned in the past direction of time. Universe is continuously expanding ever since and the galaxies are moving apart. The closer stages of the galaxies refer to the past direction of time and when they are apart refers to the future direction of time.
In the macroscopic level of the world, when we can perceive everything by our senses, there is an arrow of time inbuilt in the system and pointing from the past to the future, which clearly shows that time flows only in one direction. That means a glass filled with water, if broken and the water is spilled over the floor, cannot be restored itself to its original order; the broken glass particles will not reassemble themselves and the spilled water will not arrange itself and come back inside the glass.
Is there a Constant Universal Time?
As per Einstein’s theory of relativity, when an object moves faster, time runs slower; and when the object reaches the speed of light, time comes to a stop. If we have two atomic clocks, accurate to fractions of a second, synchronized to read the same time and one we take with us to travel around the world and come back to see that it runs slower by a fraction of a second than the clock at home. It is known as ‘time dilation’, which is very small at normal speeds but will have significant effect at speed reaching to the speed of light. Here there is no relative speed that makes the clock run slower, but the time itself slows down.
With his theory of relativity Einstein showed that gravity is another factor which affects time, besides its effects on space. Areas having higher gravitational attractions will slow down time. Sea level and mountain summit are examples, where sea level shows higher gravitational fields and slow time. The ultimate effect will be at the surface of a black hole, where time stands still with respect to our time.
Time passes at different speeds and it varies relative to the speed of the observer and gravitational fields, and hence it can be concluded that there is no constant Universal Time.
Time, the Fourth Dimension
As per Einstein’s theory of relativity, time is considered as the fourth dimension, along with the three familiar dimensions of the space like height, width and depth. Accordingly, the past, present and future, all exist alike, the separation between them is an illusion and everything in the universe can be represented in this space-time map. This concept of block universe creates more complications. If it is true that the future already exists, and it is waiting for our consciousness to approach it, then what is the relevance of our free will that is supposed to convert our fate into destinies?
In this four-dimensional space-time continuum, we can visualize the three dimensions of space, but time remains invisible to us. However, time is necessary to compare the location of an object with respect to past, present and future. An object lying within its three dimensional coordinates of space yesterday can occupy a different location today and it can be somewhere else tomorrow.
Conclusion
It can be concluded that the limiting speed by which we can travel in space is the speed of light, which is really a combination of our speed through space and through time. If we travel faster through the dimensions of space, we will travel slower through the dimensions of time, and vice versa. That means, if we travel at speed of light through space, then the limit is reached and we do not travel through time. Similarly, if we are not moving at all through space, then we would be travelling at the speed of light through time.
Time is one of the greatest mysteries that appears to be an illusion of the mind as well as real phenomenon at the same time. The invisible future gently opens the doors of the present and both the present and future merge into the ocean of the past. There is nothing left before me, no future, no present, except the shadow dance of the past. But amidst the deep silence of my existence, I can hear the horrifying footsteps of time; yes, time is there, and it will always be there, marching ahead, palpitating in tune with my heart beats.