Problem Statement

Choose popular date libraries used by your language and show the   epoch   those libraries use. A demonstration is preferable   (e.g. setting the internal representation of the date to 0 ms/ns/etc.,   or another way that will still show the epoch even if it is changed behind the scenes by the implementers),   but text from (with links to) documentation is also acceptable where a demonstration is impossible/impractical. For consistency's sake, show the date in UTC time where possible.

Let's start with the solution:

% clock format 0 -gmt 1
Thu Jan 01 00:00:00 GMT 1970