[dirtboy]

Originally the meter was equal to the length of a piece of metal kept alongside the kilogram, but in 1983 it was redefined as the distance light travels in a vacuum over 299,792,458ths of a second.

Now define a second.

[BGHater]

[frogjerk]

Now define a second.

The amount of time the government needs to decide it should infringe upon your rights.

[DuncanWaring]

1. Time required for light to travel 299,792,458 meters.

Alternatively:

2. 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.

[PapaBear3625]

Now define a second.

A second:

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 cesium 133 atom.

[r9etb]

Now define a second.

Under the International System of Units, the second is currently defined as follows:

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.

That definition, btw, is actually used in real life for any number of precise timing applications, including your ATM and cell phone transactions.

[C19fan]

From wikipedia:

Under the International System of Units, the second is currently defined as

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.[1]

[Lazamataz]

"Originally the meter was equal to the length of a piece of metal kept alongside the kilogram, but in 1983 it was redefined as the distance light travels in a vacuum over 299,792,458ths of a second."

Now define a second.

A second is the amount of time it takes light to travel 299,792,458 meters.

Q.E.D.

[varon]

Now define a second.

One Mississippi, .................

[sourcery]

Under the International System of Units, the second is currently 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.