A BRIEF HISTORY OF TIME,TIME-KEEPING AND THE CONSEQUENCES OF ADJUSTING INDIAN STANDARD TIME*

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1 ARTICLE A BRIEF HISTORY OF TIME,TIME-KEEPING AND THE CONSEQUENCES OF ADJUSTING INDIAN STANDARD TIME* D. P. SENGUPTA** This paper briefly explores the history of Time, when people became aware of breaking of a day, and its duration, descending of darkness and duration of night, dividing day and night into parts and keeping track of time. The ushering in of standard time and time zones and finally proposing an adjustment of Indian Standard Time and its likely consequences. The History of Time We seldom wonder how a day came to be comprised of 24 hours and a month on an average of 30 days. It goes back to more than five thousand years when Sumerians and Egyptians (Fig 1) had divided a day into 12 parts and a night into 12 parts. Twelve was the favoured number in those days, counting three junctions of each of our four fingers with the thumb. Decimal system overtook this and is still prevalent along with binary system of 0 and 1. If twelve hours were relegated to a day and twelve hours to a night and together they made what we call a day made of 24 hours and having observed that it took 360 days for the sun to come back to the same position (summer or winter solstice) the time length of a year was determined. Dividing a year into twelve months, the favoured number then, the length of a month was fixed at 30 days, with adjustment for the 5 extra days that make a year. Lunar months matched this. Every small town had its own time, the Sun time or the Local time. In some towns a gong would be * Dr. D.M. Bose Memorial Lecture on his 130th Birth Anniversary, 26th November, 2014 ** Visiting Professor, School of Natural and Engineering Sciences, National Institute of Advanced Studies, Indian Institute of Science Campus, Bengaluru sengupta.dp@gmail.com Fig. 1 : Ancient Egypt, Mesopotamia and Sumer. 12 SCIENCE AND CULTURE, JANUARY-FEBRUARY, 2016

sounded or cannon fired to announce the local time when the sun reached the zenith. Local time presented no problems except that the length of hours became variable.

Since 12 hours were allocated to a day and to a night, hours had variable number of minutes.

2 sounded or cannon fired to announce the local time when the sun reached the zenith. Local time presented no problems except that the length of hours became variable. Daylight persisted over long hours and nights were shorter during summer months and days were shorter during winter. Since 12 hours were allocated to a day and to a night, hours had variable number of minutes. During the Roman Empire the length of an hour varied from 76 minutes to 44 minutes and being further up in the north, London hours varied from 38 minutes to 82 minutes. It was Abu-Hassan al Marrakushi, the Astronomer Royal of Egypt during the 13 th century who fixed the lengths of an hour at 60 minutes and days and nights came to have variable number of hours. are fairly accurate, are relatively recent. Various versions of sun-dials (Figure 2) were prevalent for a long time until mechanical clocks were ushered in. What was essential to progress from using the sun for time keeping was to find some natural phenomenon that is constant and against this time could be measured. It was in Egypt that water clocks were used to keep time during the night. Without any knowledge of the force of gravity, people observed that it takes approximately the same time for a bucket with a hole to empty itself or a bulb of dry sand to empty itself into another bulb. Length of time has changed as recently as late sixties as measurement has got and more precise Before 1956: one second = mean solar day/86400 (called the mean solar second) : one second = Tropical year for 1900/ 31,556, (called the ephemeris second) : one second = 9,192,631,770 oscillations of the undisturbed cesium atom (called the atomic second) When we talk about a tropical year, it may not be irrelevant to mention about tropical year and sidereal year defining tropical year (the scale we use ) which is solar days whereas sidereal year is solar days. The History of Time Keeping From measuring the shadows of poles to atomic clocks has been a long history of development of time-keeping. The quartz clocks that are commonly used these days and Figure 3 : Time-keeping at night with a sophisticated water bucket. Figure 2 : Sundials. The most significant discovery was by Galileo when he observed, as an eighteen year old, that a chandelier in a church which was swinging, took exactly the same time to move back and forth, even though the amplitude of oscillation kept decreasing slowly, and he used his pulse to measure the time of oscillation. As we now know that the time of oscillation varies as the square root of the length of a pendulum divided by g, acceleration due to gravity. VOL. 82, NOS

Figure 4 : Galileo Galilei (1564-1642). Figure 6 : A Grandfather clock. This momentous discovery gave rise to the invention of clocks with a pendulum.

For all these clocks, springs were used for storing energy. Quartz clocks that are very much in use these days are based on a totally different principle which is known as Piezoelectricity.

Using this principle, quartz crystals are subjected to oscillating pressures which produce electricity to drive high precision stepper motors.

3 Figure 4 : Galileo Galilei ( ). Figure 6 : A Grandfather clock. This momentous discovery gave rise to the invention of clocks with a pendulum. The so-called grandfather s clock is also based on the same principle. Time-pieces, and wrist watches were based on tiny oscillating flywheels. For all these clocks, springs were used for storing energy. Quartz clocks that are very much in use these days are based on a totally different principle which is known as Piezoelectricity. In this a crystal when subjected to pressure produces electricity. Using this principle, quartz crystals are subjected to oscillating pressures which produce electricity to drive high precision stepper motors. These are high accuracy watches, the ones we use these days. Atomic clocks which are accurate up to a second up to 3.5 billion years are used for experiments demanding highest precision. Local Time and Standard Time Figure 5 : An early Pendulum clock. Mechanical clocks of various types were being made and gave the local time and not much problem was faced. People hardly travelled long distances. Horse drawn carriages were the only means of travel and semaphores (kind of hand signals) the means of sending signals. It was 14 SCIENCE AND CULTURE, JANUARY-FEBRUARY, 2016

in the 18 th century that the Industrial revolution was ushered in. Steam engines invented by George Stevenson in (1781-1848) started plying.

4 in the 18 th century that the Industrial revolution was ushered in. Steam engines invented by George Stevenson in ( ) started plying. It was around the same time (1837) that Samuel Morse invented telegraphs. These inventions are believed to have ushered in the Industrial revolution which changed the face of the world. Distances took hours to cover on horse-drawn carriages, goods took days to be transported in barges down canals in England. Steam engines covered them all in a few hours. Messages were telegraphically sent in seconds where they took hours earlier. Space and time both shrunk and local time in a town and the rail time became widely different. Figure 7 shows two times in Paddington station. Confusion was compounded with different Railway companies having their own rail times. The proliferation of rails and the confusion with time were not taken kindly by some poets and writers William Wordsworth in his protest against the building of the Kendal and Windermere Railway in 1844 wrote, Is then no nook of English ground secure from rash assault? He was concerned about the loss of timeless isolation and individuality through the impact on his quiet rural idyll of the hordes from the industrial towns. Charles Dickens expressed concerns several times, such as in Dombey and Son where he wrote, There was even railway time observed in clocks, as if the sun itself had given in. Standard Time The cause of time standardization was taken up by Sir John Herschel. In November 1840, England s Great Western railway adopted a single railroad time. It instituted London mean time for all its operations throughout the country. Other European countries followed and established a single rail time. The use of a single mean time over a large time zone was the most important step. The mean time and the rail time eventually became the standard time. England took the prime meridian at Greenwich, an observatory near London and thus Greenwich Mean Time or GMT came to be the time of reference. The US, spread over a long distance from West to East came to be divided into four time zones and with a lot of hesitation accepted Greenwich as its point of reference. The earth rotates 360 degrees in 24 hours. Every 15 degrees means shift by an hour Maritime reference also being England, the longitude passing through Greenwich was taken as zero hour. Indian Standard Time and Consequences of Adjusting it Let us now take a look at our time situation in India. From the farthest West to the farthest East, the longitudinal difference is nearly 30 degrees and there is a two hour difference in sunrise from East to West. It seems appropriate that we should have two time zones. But we have a single Time zone, with the mean longitude at 82.5 degree east of GMT passing through Mirzapore. That means we are 5 and 1/2 hours ahead of GMT. Incidentally, we belong to only 3% of nations that have fractional shift in Standard Time. Figure 7 : Rail Time and Local Time in Paddington Railway Station, England. In the year 1884 two time zones were established in India. They were called Bombay Time and Calcutta time. On January 1, 1906 British India adopted Indian Standard Time (5 hrs 30 min ahead of GMT). VOL. 82, NOS

There are repeated demands from the East and Northeast to have two time zones, since the people there suffer the inconvenience of early sunrise and early sunset. 2.

5 Between 1 September 1942 and 14 October 1945 India had War Time (1 hr ahead of IST). Assam Tea gardens follow Bagantime (Garden Time 1 hr ahead of IST). Why are we now considering any change in IST and not maintain status quo? The reasons are as below: 1. There are repeated demands from the East and Northeast to have two time zones, since the people there suffer the inconvenience of early sunrise and early sunset. 2. Expectation that two time zones will provide large energy savings. 3. Why not introduce DST or Winter time and Summer time as prevalent in the western countries? Saving energy by using the daylight longer is one of the major incentives for the actions stated above. Let us then estimate electricity savings for three alternatives; 1. Introducing Time Zones; 2. Introducing Daylight Saving Time (DST); 3. Advancing IST (YRDST). In the context of saving energy or Daylight saving a story from the past may be of some interest. Figure 8 : Five electrical regions and two Time zones. Daylight Saving Time 1 Way back in 1774, when local time existed all over the world, Benjamin Franklin, the great scientist who discovered electricity in the clouds was in Paris, when he woke up at 6 a.m. in the morning and saw that sunlight was flooding into his room (his valet forgot to draw the curtain). In those days Parisians usually woke at Midday, having fun till late hours. Franklin realized that people were Figure 9 : All India Load Curves. 16 SCIENCE AND CULTURE, JANUARY-FEBRUARY, 2016

losing six hours of precious sunlight. He proposed that the clock be so advanced that people wake up early, use sunlight and save in candle and tallow used for lighting.

6 losing six hours of precious sunlight. He proposed that the clock be so advanced that people wake up early, use sunlight and save in candle and tallow used for lighting. DST or Daylight saving Time prevalent in high latitude countries was introduced much later. Figure 10 : A typical NE load curve, the shaded area represents the energy saving In all ways of adjusting IST to save energy, the saving accrues from using sunlight longer in the evenings and using less of electric lighting. But how do we calculate energy savings in each of these cases? People switch on or switch off lights randomly. It gets dark in different parts of the country at different times as we observed earlier. The whole process is so random that in the same household lights are switched on and off in different rooms at different times. Some individuals switch off lights when they leave a room. There are others who leave the lights turned on. Inspite of this randomness one can find an overall pattern when millions of electricity demand add into what is called a Load Curve which depicts electricity demand met in MW against the hour of the day. There is a commonness of human habits such as turning on water heaters in the morning during winter months and switching on lights as it begins to get dark. This is clearly reflected in the hump in the morning demand during winter months and a hump or peak in the evening, depending on when it begins to get dark. In other words, the statistical averaging of very large stochastic data, yields certain patterns due to the commonness of human habits. The blue line in Fig.9 represents demands on a particular day in the month of May and the red line the demand pattern during the same day in January of the same year. (The reader can interpret the undulations of the demands during other hours) Figure 11 : Advance IST by half an hour just once. If the IST is altered marginally (e.g., advancing IST by half an hour) people s VOL. 82, NOS

7 habits will not change. Sleeping hours will remain conserved. Let us assume that Business hours and timings of industries remain unaltered. Advancing IST will lead to borrowing half an hour of daylight from the morning and using it during the evening. The advancing of the Standard time will extend the evenings and delay the switching on of lights by half an hour and the shaded area CC DD is the saving energy incurred for a typical load curve from the Northeast. The energy saving does not seem very large compared to the total energy used during a day. For India, taking the country as a whole, (Fig. 9) where the annual electricity consumption is about 700 billion units, the saving comes to 2.7 billion units which constitutes 0.3% of the yearly demand. The actual saving comes to 2.7 billion units per year which constitutes only 0.3% of the yearly demand. But the saving during the evening peak hour which most electricity companies find it hard and expensive to meet, constitutes 15% of the energy demand which is not insignificant. Exhaustive studies carried out for the other two alternatives, namely, dividing the country into two time zones and /or having winter time and summer time lead to lesser savings in energy 2-4. What is most important is that in advancing IST by ½ hour means adjusting the clock only once, taking IST from the present 5 ½ hours to 6 hours ahead of the GMT. Dividing the country into time zones implies having to adjust the clock every time one crosses the zonal boundary and introducing winter time and summer time demands having to change the clock twice in a year. This may cause endless problems and not worth introducing in an overcrowded semiliterate country like hours. (It is worth noting that China which spreads much wider from East to West than India has a single time zone and advanced by one hour from the mean longitude Besides, dividing the country into artificial zones may have undesirable political consequences. Our Recommendation Our recommendation is to advance IST by half an hour, changing the clock only once. This will a) lead to Main-streaming the North East b) bring us among 97% of nations having integral time shift c) extended daylight during evenings will make it safer for working women d) lesser cancellation of sporting events and more playtime for children e) Increased commerce due to longer evenings f) less motor accidents expected. On the other hand extended darkness during winter mornings in the North and North West may make it awkward for school-going children (This may be overcome by having winter time / summer time for schools) and there may be more flight cancellations in foggy dark mornings. Conclusion From the Babylonian days till now, it has been a long journey for human civilization. Awareness of time and the mode of time keeping were moving at a certain pace with solar time or local time being enough for the relatively slow life that people had. Industrial revolution brought speed and local time had to make way to standard time. In India we have stuck to the British decision of having a single time zone 5 ½ hours of GMT. Demands for two time zones for India are being made from time to time. In this paper we have given a brief account of a novel method of calculating energy saving due to the change of time based on load curves. The results of our studies have led us to conclude that advancing IST by ½ hour is the best option for us and even better than status quo. Acknowledgement The work on adjusting Indian Standard Time was jointly carried out with my colleague Professor D.R. Ahuja, at NIAS with financial support from the Bureaue of Energy Efficiency, Minsitry of Power, GOI. References 1. D. S. Prerau, Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time, Thunder s Mouth Press, New York, (2005). 2. D. R. Ahuja, D.P. Sen Gupta, and V. K. Agrwal, Energy savings from advancing the Indian Standard Time by half an hour. Current Science, 93 (3), (2007) 3. D. P. Sen Gupta and D. R. Ahuja, Options for adjusting Indian Standard Time for saving energy. NIAS Report Number R Bangalore (2011). 4. D. R. Ahuja and D. P. Sen Gupta, Year-round daylight saving time will save more energy in India than corresonding DST or Time zones, Energy Policy, 42, (2012). 18 SCIENCE AND CULTURE, JANUARY-FEBRUARY, 2016

TIME. Astronomical time Time is defined by astronomical cycles. The day is the average time from noon to noon (the solar day).

TIME. Astronomical time Time is defined by astronomical cycles. The day is the average time from noon to noon (the solar day). ASTRONOMY READER TIME 2.1 TIME Astronomical time Time is defined by astronomical cycles. The day is the average time from noon to noon (the solar day). The month was originally based on the average time