2007-07-15 22:33:22 · 5 answers · asked by genesis 1 in Science & Mathematics ➔ Physics
From the National Institute of Standards and Technology (NIST) http://www.mel.nist.gov/div821/museum/timeline.htm
On October 20, 1983, the meter was redefined. The definition states that the meter is the length of the path traveled by light in vacuum during a time interval of 1/299,792,458 of a second. The speed of light is
c = 299,792,458 m/s
The second is determined to an uncertainty, U = 1 part in 1014 by the Cesium clock. The General Conference made the iodine stabilized Helium-Neon laser a recommended radiation for realizing the meter at this time. The wavelength of this laser is
λHeNe = 632.99139822 nm
with an estimated relative standard uncertainty (U) of ± 2.5 x 10−11.
2007-07-15 22:46:48 · answer #1 · answered by Pro bono publico 4 · 0⤊ 0⤋
(Not really an answer)
The meter was ORIGINALLY defined by French scientists n the late 1700's to be one ten-millionth of the distance from the equator to either pole.
The meter (or metre) was then computed as best as possible, given the knowledge and techniques of the day.
They were off a bit, due to errors in measuring, and errors in their assumptions (the Earth is not quite a perfect sphere), but they wer epretty close.
What I find AMAZING, is that this almost arbitrary choice puts the speed of light (which wasn't even a CONCEPT back then) the only TRUE constant, within 0.07% (7 parts in 10,000) of exactly 300 million meters/second!
2007-07-16 04:01:47 · answer #2 · answered by tinfoil666 3 · 0⤊ 0⤋
The metre is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second
2007-07-15 22:37:54 · answer #3 · answered by Martin S 7 · 1⤊ 0⤋
1 metre = 100 cm = 60 inches.
e.g.
I am 1.6 m tall, 160 cm tall or 63 inches tall.
2007-07-15 22:38:49 · answer #4 · answered by jade2a6 2 · 0⤊ 2⤋
http://www.surveyhistory.org/the_standard_meter1.htm
2007-07-15 22:43:40 · answer #5 · answered by oregfiu 7 · 0⤊ 0⤋