Is there a metric unit of time?
-- Matty, San Diego
Yesish. That's new elf shorthand for "the answer to your basic question is yes, but as usual nobody could leave well enough alone, so there are all kinds of ifs and buts that make the question more complicated than it seems, and we intend to bore you with all of them unless someone stops us." I mentioned to the elves that they'd already managed to bore me, but they're undeterred.
The metric measurement of time is the second. At least that's the word used to designate the basic metric unit of time. The second itself has been redefined several times. A century ago, a second was 1/86,400 of a mean solar day. In 1955 it became 1/31,556,925.9747 of a particular solar year (1899).
With the advent of the cesium-beam atomic clock (AM-FM/snooze alarm optional), science finally pinned down the wily second: "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom." Will this improve our on-time record at work? I don't think so. But of all measurable things, time is the most ephemeral. Like putting smoke in a box. It's expandable, it's compressible, we can measure it any way we want, and it exists only because we say it does. Time, in fact, was invented shortly after the discovery of the sales meeting.