Also see this experiment from the same site: http://leapsecond.com/great2005/ Qu...

e12e · on April 16, 2014

This got me thinking: How can you tell that two clocks are 22 nanoseconds apart? I mean, it's not like you can look at a display or anything.

This is a bit of a rhetorical question, I'm sure Google holds many answers involving decaying isotopes or measuring laser pulses or something.

sanxiyn · on April 16, 2014

This entry from "Time and Frequency from A to Z" published by NIST should get you started.

http://tf.nist.gov/general/enc-ti.htm#timeintervalcounter

jloughry · on April 16, 2014

How can you tell that two clocks are 22 nanoseconds apart?

If the clocks are in the same room and you have a fast oscilloscope at hand, it's easy.

If the clocks are more than about 6 metres apart, it really is impossible.

dragonwriter · on April 16, 2014

So, if you have a room that's got a dimension larger than 6 meters, and a fast oscilloscope, you can have a situation in which it is both easy and impossible?

jloughry · on April 16, 2014

I get in trouble regularly with my wife because I've been trained my whole life to think in a particular way, and that's not how other humans are wired:

    if (a) {
        b;
    }
    if (c) {
        d;
    }

versus

    if (a) {
        b;
    }
    else if (c) {
        d;
    }

She has mostly learned to put up with me by now, but the difference (how programmers think) still comes out sometimes.

Edited to explain: programmers don't think exactly like other humans.

dragonwriter · on April 16, 2014

Of course, in programming in the first case, "b" and "d" both happen when "a" and "c" are both true in many languages, unless "b" is something like "return e"

But, anyway, I was mostly joking -- its not like your meaning was at all unclear.