Time is the most mysterious thing among the various natural resource elements available to mankind. It is one of the most amazing dimensions in the universe as it flows in only one direction that is past to present and present to the future. Science is still to find exactly how time started and when it is going to end if there is any such possibility of that end. Though scientist has long back proposed the Big Bang theory for the beginning of the universe, the event which can also be thought as the beginning of time, many scholars refute that theory especially regarding the start of the time because it then leads to another difficult question as what was before that so-called singularity.
The unique thing with time is its flow direction - it flows only in the forward direction. Once a time is missed it can not come back or we can not go back to it. Even if we capture the image of the event by going faster than light (which is, of course, an impossibility as per the Einsteins theory of relativity) and see it then it will be not real but only a virtual image of the event. Under these natural boundaries, understanding the mystery of time becomes very intriguing and challenging subject. Science is relentlessly working in pursuit of unravelling it. The future is full of possibilities of getting more and more knowledge about this mysterious entity called time.
What is Time?
Time has no fixed size. It does not have any shape. It is an abstract thing and can be conceptualised by the activities happening in its domain. There is a reference time as provided by nature to us. For example, a complete day can be a unit of time say from morning to next morning and depending upon how much longer an activity takes, we say that it took more or less time as compared to that reference. Time can be quantitatively large or small depending upon the events. For example, it is very large for the geological processes on earth - millions of years took for the evolution of humans from apes. Further, the mighty Dinosaurs survived on earth for millions of years. It takes large time for intermittent ice ages to emerge on earth. At the same time, it is very small when we see the age of humans as It is an average 80-90 yrs only for a human life span. If we see from the length of life of pet animals It is still smaller as compared to our life span. Going to still smaller time frames It is very small for a wink of an eye. A gun fires in no time. At atomic and molecular level things happen in Milli and Microseconds. So time can be very small as well as very large. It depends on which activities and events we are considering.
The human understanding of time is linked with the planetary motions that are day and night and the four seasons in a year. We derive our time calculations from them only. Every year the seasons repeat for us reminding that one cycle is complete. The primitive generations had no way of counting these cycles and probably did not know how many years a person lived on Earth before dying. The only thing they had seen was a person dying as a child or young or old and from that, they could guess roughly that the person lived for less time or more time. It is only when the early humans learned to count that they could start counting the one full cycle of seasons (year) to arrive at as how many years a person lived. This was the first rough step in measurement of the time. Subsequently, the various methods to measure time developed and the position of the sun became the primary factor in assessing this entity. The inquisitive minds observed that the shadow of the objects became smallest at noontime while it became bigger and bigger other times. This gave a rough method to track time seeing the shadow of a stick on the ground. The sun clocks were born in this fashion. The human minds were always searching for answers to the problems in nature and in that pursuit, many riddles associated with time were untangled. This gave rise to a detailed understanding of the change in day and night duration during the year and was confirmed from the repetitions of similar cycles with the advent of time.
Parallel to these findings there was a lot of work done by the ancient scholars and knowledgeable people to track the star constellations in the night sky and to the surprise and astonishment of many, it was found to follow a yearly pattern. With the advent of naked-eye astronomy this knowledge helped the learned people to understand the positions of planets and stars in the night sky. Everything fitted in place when seen from the yearly cycles. The repetition of constellation patterns after a year confirmed the rounds of Earth around Sun and this was the first step in starting the measurement of time in years as each round corresponded to one year.
With the onset of scientific developments, more control on time measurement could be made possible and accurate clocks were designed to measure the time. The division of one day in 24 equal parts gave rise to modern hour system which was further fine-tuned by dividing it into minutes and seconds. Today our life is tied to our activities based on these smaller units of time. Though different scholars made different calendars, the most common followed is the gregorian calendar which we all are using today. Due to religious reasons, many people are using the Panchang (a type of calendar only) or equivalent calendars as developed in their own societies. These are related more to festivals and solar and lunar eclipses. They are not very accurate but have internal correction systems after every year or after a few years so that they match with the planetary positions. The scholars in the past meticulously noted these movements of planetary bodies and made so many measurements which match magnificently with the modern astronomy. The science of stargazing and acquiring knowledge of solar system and its planets gave birth to another branch of knowledge that is astrology which is a method to tie up one's fortune and luck to the position of the planets in the constellations at the time of the birth of a particular person. Of course, that is more of a question of faith rather than the true science.
Time and Universe
Time becomes a more mysterious entity when we perceive it in the context of the universe. It is well known that universe is a very very big space assumed to be infinite in its extent and as per a rough scientific estimate, the so far known size of the universe is more than 93 billion light-years. It is a mind-boggling number as one light-year is the distance which light travels in 1 year. We have to multiply this distance with 93 billion to arrive at the known size of the universe through the fact is that the universe is still bigger than that. It takes significant time for light to reach from a distant star to earth and what we are seeing today is not the present form of that star and the associated galaxy and in fact, we are seeing is the galaxy back in time. That time is in million or billion years. Sun is the nearest star but when compared to the large distance in the universe it is very near to us. Light takes only about 8 minutes to reach Earth from the Sun.
Scientists and scholars talk about alien life in the universe. So far no concrete confirmatory information is available about them. Even if they exist it is not necessary that they will co-exist with us. They might be there in the universe separated by a large time interval and then there is no chance of them meeting each other (and of course with us) in reality. So these are the puzzles which can only be understood when we consider the vastness of time.
Time is an integral part of the universe as things are moving and happening in the entire universe at a local level in galaxies or a universal level where more galaxies are moving away from each other. As per scientific studies, the universe is expanding and no one knows till when it will remain expanding. Even if it stops and starts coming back to the so-called singularity, time still flows in a forward direction.
Time is a complex thing but can be understood while comparing the different events taking place and incurring at different time intervals and that is the only relation where one can say that more time was spent in an activity or less time was spent. It is only the planetary motion of the planets around the Sun in our solar system that we have conceptualised the basic units of time as day or night and a year. These years were then divided in some months for convenience only. Our body has biologically adapted to that time frame during the evolutionary phases by working in the day and sleeping in the night. The time is still flowing ahead.
Wonderful write-up on time. The next extension of it could be to include space-time relation and it's manifestation in the human life.
A very well written thought-provoking article on understanding the basics of time. Time is indeed a mystery!
Nice article. What type of studies has been conducted or are being conducted to conclude that universe is ever-expanding? Is any data is available in this study?
The author has wonderfully tried to correlate the time events and time intervals with absolute definition of time.
Some more details about the author may be included in the introduction.