Absolute Time  Is a precise measurement.  Can refer to specific events, dates or moments.  Uses numbers and is exact.

Examples  Mrs. G was born on May 11,  The power went out at 5:23 and 6 seconds.  The bank opens at 9:30.

Relative Time Is time measured in relation to other things

Examples  Mrs. G was born during the era of big hair  The power went out during Seinfeld  The bank opens at the same time as the mall

Man and Measuring Time Throughout history, man has devised many ways of keeping time Examples:  Sundial: A device for telling time of day by the shadow which sunlight produces on the instrument.

 Ropes: When burned, knots tied at regular intervals would measure time.  Candles: The candles would have grooves carved into them and, when burned, each groove represented a specific amount of time.

 Hourglass: It tells time by means of sand trickling through a narrow opening.  Water Clock: It measures time by allowing water to drip from one marked container into another.

Mechanical Clocks: They were invented in 1656.

Cyclical Time and Linear Time Cyclical Time  Based on the cycles of nature.  Repeats over and over in a cycle.  Is a measurement of natural cycles and is an attempt by humans to live in harmony with the cycles of nature.

Cyclical Time cont’d  Days – are based on the rising and setting of the sun.  Months – are based on the cycles of the moon.  Years – are based on the Earth’s cycle around the sun.

Three examples of cyclical time measurement: 1. Stonehenge: Is located on the Salisbury Plain in southern England. Allowed for some measurement of cyclical time.

2. Medicine Wheels:  Are found on the prairies of North America.  Were built by the Plains Indians.  Were mostly used as calendars.

3. Calendars:  Were designed to measure time and organize society.  The first calendar used in the western world was the Julian calendar which was introduced by Julius Caesar.  In 1582, Pope Gregory XIII developed the Gregorian calendar, which replaced the Julian calendar.

Linear Time:  Is a measurement invented to use in long range planning.  Can be plotted on a timeline.  Always has a beginning and an end.

Three examples of linear time measurement: 1. Personal Time:  Is time reflected by the life span of an individual person.  Includes events such as birth, graduation, and marriage.  Is measured in days, months, and years.

2. Historical Time:  Is time since people began keeping records of historical events.  Includes important political, social, and economic events.  Is measured in years, decades, centuries.  Remember: B.C. means “Before Christ” and A.D. means “Anno Domini” (In the Year of Our Lord).

3. Geological Time:  Is time reflected by the age of the Earth.  Includes periods in the Earth’s geological development and the development of life on Earth.  Is measured in epochs, periods, and eras.