History of Measurement
Measurement has been fundamental to human civilization since ancient times.
Ancient Measurements
- Cubit — based on the length from elbow to fingertip (~45 cm)
- Foot — based on the human foot (~30 cm)
- Grain — one of the earliest weight units, based on a grain of barley
Medieval Standards
Kings and rulers standardized measurements for trade. Henry I of England reportedly defined the yard as the distance from his nose to his thumb.
The Metric Revolution
In 1795, France introduced the metric system based on natural constants. The meter was originally defined as one ten-millionth of the distance from the equator to the North Pole.
Modern Standards
Today, the International System of Units (SI) defines seven base units. The meter is now defined by the speed of light: the distance light travels in 1/299,792,458 of a second.