[LEAPSECS] "why time is difficult"

[Zefram]

At two Perl conferences in 2011 I presented a talk titled "why
time is difficult", in which I explain the present profusion of
time scales.  Video of the more recent performance is now available
at <http://www.presentingperl.org/lpw2011/why-time-is-difficult/>.
The content isn't anything new to the regulars here, but it may be a
useful codification of this knowledge.

-zefram