November 2, 2010 > What time is it?
What time is it?
A glance at a watch, clock or computer screen can usually answer this question without much thought or calculation. However, an accurate answer really depends on many factors including where the question is asked and how it relates to the location of others. Without study of Einstein's Theory of Relativity, we understand that people who communicate with different areas of the globe will receive a variety of answers to the question. Noon in one location is not equivalent to noon in another.
Calculating time has always been important, but methods used to determine time have focused on the position of the sun in the sky at a particular location. Noon was proclaimed when it reached its zenith. However, the relationship of the sun to someone standing on Earth changes depending on where that person is. As sunlight travels from East to West, time moves with it. Simple devices called sundials measured time by monitoring the position of a shadow as it traversed a circular pattern with the apparent movement of the sun (actually rotation of the earth as it travels around sun). When the sun is directly overhead, no shadow is cast; dividing the rest of the day into equal segments results in hours.
Mechanical and atomic clocks refined and eliminated the need for sundials and dependence on sunny days to determine time. Nighttime calculations were also easily determined. However, time differences between towns remained a problem. Each village, town and city set their clocks to their particular relationship with daylight.
Those who cared most about these discrepancies were people who traveled frequently between towns. Knowing what time each individual location used could be a Herculean task. Calculating time when traveling quickly between widely spread areas was especially daunting. Challenges for railroads in the 19th century finally resulted in the beginning of standardized time. The Great Western Railway instituted a single time system called "London Time" in November 1840. This move was quickly followed by other railroads although many municipalities did not easily abandon their own unique timekeeping. Subsequently a move to Greenwich Mean Time (GMT) standardized time throughout the country under the Statutes Act which took effect on August 2, 1880.
Similar conversions of timekeeping took place in other countries but not without controversy. While railroads understood the need for standardized time, others did not and resisted. Usually a prominent town clock was used as the standard for timekeeping and those travelling were expected to honor the local official time. Time "meridians," heavily promoted by Canadian civil and railway engineer, Sandford Fleming, were instituted by United States and Canadian railways in 1883. The International Prime Meridian Conference of 1884 adopted an international standard. Finally, the United States Standard Time Act of 1918 created standard time zones under the auspices of the Interstate Commerce Commission. When the Department of Transportation was created in 1966, it assumed responsibility for time laws. Just as time does not stand still, neither have the official boundaries of time. Many boundary changes have occurred throughout the years and the institution of Daylight Saving Time complicated timekeeping even further.
Daylight Saving Time (DST) is a modification of time that began in World War I as a method to conserve fuel by extending evening daylight hours. Germany and its allies began observing DST and other countries quickly followed suit. The United States began DST in 1918. Since length of day and night depends on the degree of tilt either toward or away from the sun, those areas close to the equator experience little change and therefore had no reason to adopt these time changes. This alteration of the clock was left to area preferences between World War I and World War II but in 1966, the Uniform Time Act standardized the length of DST. The European Union standardized "European Summer Time" in 1996 which extends from the last Sunday in March through the last Sunday in October. Countries in the southern hemisphere follow a different schedule since their orientation toward the sun is the opposite of countries in the northern hemisphere.
Originally, DST in the United States extended from the first Sunday in April until the last Sunday in October. Subsequently, legal changes in 1986 and 2005 due to pressures of energy supply and consumption have modified DST and it is now observed from the second Sunday in March until the first Sunday in November. A few locations within the United States have chosen to remain on Standard Time throughout the year.
On Sunday morning, November 7, the time change back to Standard Time will result in an extra hour of sleep for many but the simultaneous loss of evening daylight as sunset moves an hour forward. Even for those a bit confused and resentful of this time change, the reasons for it are actually the result of practical considerations. As "Sam" sang in the 1942 hit movie Casablanca, "The fundamental things apply; As time goes by."
Although there are many good references on the internet, a resource worth reference is http://www.webexhibits.org/daylightsaving/index.html
Daylight Savings Time ends this year on Sunday, November 7 at 2 a.m. Remember to turn your clocks back one hour. It is time to "fall back" and enjoy an extra hour of sleep (Spring forward, Fall back).