The question is very simple but very difficult to answer. No universally acceptable definition of time is given in the modern scientific technical parlances. However few features of time which are described by scientists and intellectuals are given below:-
• What clocks measure - Albert Einstein, Donald Ivey, and others.
• What prevents everything from happening at once - John Wheeler, and others.
• A linear continuum of instants – Adolf Grunbaum
• A certain period during which something is done- Medical Dictionary
• A continuum that lacks spatial dimensions- Encyclopedia Britannica.
The above features of time can not materialize a conclusive definition of time. People visualize time according to their circumstances, culture, perception, and of course scientific inventions.
The contemporary concept of time
Our time calculation mechanism is based on the period which earth takes to rotate on its axis; and period which it takes to revolve around the sun. We divide one rotation period of earth in to 24 parts and one part is one hour. Likewise one complete revolution of earth around sun is considered to be one year. The year is divided in to 12 months. Both these periods are divided or sub-divided or multiplied to get smaller or bigger units. These various units of periods of rotation and revolution are called time.
Thus one thing is apparently clear that the concept of time which we developed is earth and sun centric. It means time, what we perceive today, is a period for which earth will rotate and revolve around its orbit and axis. The single rotation of earth on its axis is called a day which is uniform unit of time. Therefore as long as the earth will rotate and revolve, the phenomena of time will exist.
But suppose if due to any cosmological incident or otherwise earth stops it’s rotation or revolution i.e. earth becomes non-existence, will time come to an end? Or the pace of earth’s revolution and rotation is changed due to some reason then what will happen to the existing concepts of time? In these cases how the time will be calculated?
In a case if earth comes to an end then earth centric time will come to an end but time will exist in relation to other bodies which are revolving around a centre and rotating on its axis.
By this fact we may conclude that:-
1. The time is a relative concept, corresponding to a particular particle or body.
2. The rotation and revolution of particle or body is essential for the creation of time.
3. The time units will be unique and specific for every particle or objects because speed of rotation and revolution for an object is unique.
4. If the rotation or revolution of a particular object comes to an end i.e object becomes non-existential, the time in relation to that particular particle will come to an end.
On the basis of above features we may try to define time in the following simple manner - “The time or kala is an existential period of particular particle and one rotation period of that particular particle on its axis is single unit of time”. Thus every particle has its time period and a unit.
It is apparently clear that time corresponds to the life or existence of a particle or body, and will come to an end in relation to that particular particle, if it ceases to exist or come to an end.
The beginning and end of time
Now question arises when the time will begin? Answer is very simple. When the particle is born time will also begin. Thus creation also creates time and destruction brings its end.
The fusion and fission are two processes of creation and destruction in the cosmos. All objects and particles are the result of either fusion or fission. When two particles fuse a new particle is born and energy is released. Likewise in fission, bigger particle breaks in to two or more particles and again energy is released. These newly formed particle or bodies are not free or independent. They immediately after their creation start revolving around a central body and rotating on its axis. Their existence will depend on revolving and rotation. If due to any reasons rotation and revolution are stopped, existence of that particle will come to an end and it will be attracted by another particle. Ultimately it will fuse or submerge with bigger one and affect it. It is a continuous process of creation and destruction. So the time begins and comes to an end. The process is also described in Indian scriptures particularly in ‘Vishnu Purana’.
Indian concept of time
The 24th shloka, second chapter of ‘Vishnu Purana’ describes the Indian concept of time. Here the time is termed as ‘Kala’. The shloka is given below:-
विष्णेः स्वरुपात्परतो हि ते द्धे
रुपे प्रधानं पुरुषश्च विप्र l
तस्यैव ते अन्येन धृते वियुक्ते
रूपान्तरं तद् द्धिज काल संज्ञम् l l (24)
हे विप्र! विष्णु के परम ( उपाधि रहित) स्वरुप से प्रधान और पुरुष – ये दो रुप हुये; उसी (विष्णु) के जिस अन्य रुप के द्वारा वे दोनो (सृष्टि और प्रलयकाल) में संयुकत और वियुकत होते है, उस रुपांतर का नाम ही काल है l
O learned man! The two allotropic form of ‘Vishnu’ – ‘Pradhan’ and Purush’ evolved from absolute stage of ‘Vishnu’. Both allotropic forms with the help of another “Vishnu’ merge together (creation) and disintegrate (destruction) - this transformation is called ‘Kala’.
It means ‘Kala’ is the existence period of a particle and particle will exist as long as it revolves around a centre and rotates on its axis. One complete rotation on its axis will be one unit time in relation to that particular particle. As soon as the particle disintegrates, its ‘Kala’ will come to an end i.e. the end of time in relation to that particular particle.
Dimension of time- the ‘Kala chakra’
It’s another pertinent question that dimension of time is linear or circular. The modern civilization and science consider time a linear dimension preposition. But how it can be possible when we consider time unit as period taken by a particle in one complete rotation on its axis? Rotation is always circular it can never be linear. And if rotation can never be linear then how time can be linear. It is always in circle or cyclic in nature i.e cycle or ‘Kala Chakra’.
1. Time is a relative concept. It is related with a particle or body.
2. The time originates with the origin of a particle and come to an end with the end of particle.
3. Its particle or body specific i.e. every particle has its specific time.
4. One rotation of a particle on its axis constitute single unit of time.
5. The revolution period of a particle around a centre is the life of a particle. Its life will come to an end as soon as it stops revolution.
6. Time in relation to a particular particle will exist till particle exist. If the existence of particle comes to an end, the time for that particular particle will also end.
7. Time has a circular dimension not liner.
Time is due to existence of particle or object. It means time exists because earth exists i.e. first particle is created which in term results in to time. That is why, time follows us and not we follow time.