On May 21, 2008, at 5:15 AM, Ian Lynch wrote:
Second I believe is defined by atomic clocks these days
The second is "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."
The meter "is the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second."
The kilogram is still defined by a lump of metal in Paris; this is agreed to be unsatisfactory, and work is being done on redefining it (for example, as the mass of x number of carbon-12 atoms), but all of the methods proposed to date have practical problems.
-- John W Kennedy "The blind rulers of Logres Nourished the land on a fallacy of rational virtue." -- Charles Williams. "Taliessin through Logres: Prelude" --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
