Have the definitions of time and metric meter changed over years?

In summary, the French developed the metric meter by measuring the distance between the equator and north pole and then dividing it by an integer. This is still the definition for meter. However, a second is now defined by the number of oscillations of an atomic clock, rather than being divided from a day into 24 hours, 60 minutes, and 60 seconds. The kilogram is still defined by a specific block in France.
  • #1
arabianights
62
7
i remember the French came up with metric meter by measuring the distance between equator and north pole and then divided by an integer to come up meter. it that still the defintion for meter?

also, it seems now that a second is defined by the integer number of oscillation of atomic clock instead of divided a day divided by 24 hours by 60 minutes by 60 seconds.

just want to get a clear idea how these basic units are defined in modern times.
 
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  • #3
very good, thanks!
 

1. What is the current definition of time?

The current definition of time is based on the International System of Units (SI) and is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium 133 atom.

2. Has the definition of time always been the same?

No, the definition of time has evolved over the years as our understanding and measurement techniques have improved. The current definition was adopted in 1967 and replaced previous definitions based on the Earth's rotation and the motion of celestial bodies.

3. How has the definition of the metric meter changed over time?

The original definition of the metric meter was based on the length of a pendulum with a half-period of one second. In 1799, it was redefined as one ten-millionth of the distance from the equator to the North Pole. In 1889, it was redefined again as the distance between two lines on a platinum-iridium bar, known as the International Prototype of the Meter. In 1960, the meter was redefined in terms of the wavelength of light. Finally, in 1983, the meter was defined as the length of the path traveled by light in a vacuum during a specific amount of time.

4. Why have the definitions of time and the metric meter changed over the years?

The definitions have changed in order to improve the accuracy and precision of measurements. As our technology and understanding of the physical world has advanced, we have been able to redefine these units in more precise and consistent ways.

5. Will the definitions of time and the metric meter continue to change in the future?

It is possible that the definitions may continue to evolve as our scientific knowledge and measurement capabilities improve. However, any changes will likely be minor adjustments rather than major redefinitions, as the current definitions are highly accurate and consistent.

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