Measurement

MEASUREMENT
Lesson 2 - Page 6

Anders Celsius of Sweden

Aztec Calendar

Degrees Celsius use the 100 degrees increments with 100 degrees representing the boiling point and zero the freezing point of water. The Celsius temperature scale named after Anders Celsius (1701-1744) is part of the "metric system" which is an International Systems of Unit (SI) and is used throughout the world. The general public in the United States still uses Fahrenheit.

Scientists, especially those that work in high and low temperatures use a third scale, called the "absolute" or Kelvin scale. This scale was developed by William Thomson also known as Lord Kelvin (1800’s), a British scientist working in high temperature ranges. Scientists have determined that the coldest it can get (theoretically) is minus 273.15 degrees (absolute zero) Celsius. At this temperature scientists believe that molecular motion would stop. You can't get any colder than that. Why in the world would you create a new system which is just 273.15 degrees from Celsius? Simple, scientists working in these ranges did not want to deal with negative numbers.

Time is a difficult to quantify. Time can be in the past, present, and future. Civilizations have always had the challenge of how to use the concept of time so it was repeatable.

Instruments like sand timers were used to calibrate a small slice of time. Calendars and clocks help us determine time by using the rotation and revolution of the Earth in relationship to the Sun. Calibration is more difficult. A photon (particle of light) determines a second which modern atomic clocks are based. Determining past time includes relative and absolute methods usually based on mathematical determinations. Time is measured in seconds, minutes, hours, days, and years.

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