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How the Meter Evolved: Light Speed Redefines Measurement

11/11/2025

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Summary

Story summary

In 1983, the meter was redefined as the distance that light travels in 1/299,792,458 of a second, using the constant speed of light in a vacuum.
Before 1983, the meter was defined by physical artifacts, notably a platinum-iridium bar that served as the global standard until 1960.
After 1960, definitions shifted to atomic interferometry and specific wavelengths of light.
Accurate measurement standards are crucial for scientific endeavors.

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Story summary

In 1983, the meter was redefined as the distance that light travels in 1/299,792,458 of a second, using the constant speed of light in a vacuum.
Before 1983, the meter was defined by physical artifacts, notably a platinum-iridium bar that served as the global standard until 1960.
After 1960, definitions shifted to atomic interferometry and specific wavelengths of light.
Accurate measurement standards are crucial for scientific endeavors.