By Professor Syed Ibrahim Rizvi
What is time? Well, this question may appear to be stupid to most of the people but the answer to this question brings forth many interesting facets. As one goes deep into the ‘concept of time’ a large number of beliefs lose their relevance. As we look deeper into time, our mind starts going dumb.
The classical definition of time is as follows “Time is the ongoing sequence of events taking place. The past, present and future. The basic unit of time is the second. There are also minutes, hours, days, weeks, months and years. We can measure time using clocks”. But let me start by saying that this is the human definition. What about animals, bacteria and plants? Do other living organisms also perceive time as humans do? On a larger scale, one may also ask whether time is universal or it is an entity which is just confined to earth? When such questions are posed with respect to time then the human definition starts losing its meaning.
Essentially time is governed by the movement of earth on its axis which creates day and night. This rhythmic change of day/night has provided living organisms with a tool to calibrate their routine into light and dark phases of this continuous rotation of earth. It is just ‘recent’ in the evolutionary history of humans that we have started measuring time. It was around 3500 years back that there is the first recorded invention of any type of measuring device with the creation of the ‘water clock’ by the Egyptians or Babylonians.
Having understood that time for earth inhabitants is dependent on the rotation of earth which makes sunlight fall on different parts of the earth at different periods, one must then acknowledge that ‘time’ as we perceive is not a universal phenomenon. Our companion in space, the moon, has a very different concept of time. And it may seem weird, but an infinite number of stars in the sky may not be experiencing time, as humans do on this earth. Time would be stagnant in all those heavenly bodies in this universe where there is no rhythmic or constant cue which can be used to calibrate the past, present or future. So, we come to the conclusion that there are large number of places in this Universe where ‘time’ is static!
Coming back to earth, time started when earth was formed some 4.5 billion years back. It was the force of gravity of the mighty sun which prevented the earth from moving too far from the sun and again due to centrifugal force the earth was put into an orbit on which is revolves around the sun. The mighty forces which played their part during the ‘big bang’ created the earth with a core which is filled with molten metals comprising mainly iron and nickel, this core is continuously swirling making the earth rotate. The force created by the molten material in the core of the earth makes the earth rotate from west to east in a constant manner.
Interesting it may appear that the rotation of earth which is now 24 hours had not been constant throughout the last 4.5. billion years. About a billion years back, the earth rotated much faster and it took approximately 17 hours for one complete rotation. In its inception, the earth moved even faster and there was a point in time when the rotation of earth took just 4 hours! Thus ‘time’ is not a constant phenomenon.
As all living things on this earth have evolved under the influence of earth’s rotation, life has adjusted to this continuous change in day/night of the earth. All living organisms have made intricate arrangements in their physiology and behavior, synchronizing with the change in day and night. Humans display interesting changes in physiology which is related to time of the day. Several hormones are secreted at different rates depending on the hour of the day. Blood pressure, temperature and pulse rate vary rhythmically in the 24 hour period. It is a common observation that heart attacks usually occur between 4 and 8 in the morning.
Since all forms of life has adjusted to the circadian rhythm of time on this planet earth, even small man-made changes make big alterations in our health. Mankind is just beginning to understand the problems associated with artificial light. A new term has come up. ‘Artificial Light at Night’ or ALAN which tries to explain the role of artificial light in our circadian physiology.
Thus ‘time’ is something which is there but then it is not there. Poets say ‘time’ is fleeting. In the passage of time, one is reminded of a few lines of T.E. Bryan’s poem : Fleeting Moment
In time’s embrace, we find both loss and gain,
A fleeting moment’s power, joy, and pain,
So let us savor every breath we take,
For moments lived are memories we make.
(Author is Professor at bio-chemistry department
University of Allahabad)