History of Second

	Revision 5 . . November 6, 2001 8:01 am by (logged).111.13.xxx
	Revision 4 . . July 27, 2001 4:02 pm by Tobias Hoevekamp

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Changed: 1c1

Second is a unit for time, and one of seven SI base units. It is defined as the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom.

Second is a unit for time, and one of seven SI base units. It is defined as the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.