The epoch is the moment when the time starts. For the mesoamerican Long Count, this was 13.0.0.0.0, August 11, 3114 BCE, or HJD 584,283.

For Unix, the epoch is January 1, 1970, 00:00:00 (UTC), and time.time_ns() just returned 1712962363486034854. A quantity of 1.7e+18 is about 1/5th the number of air molecules in a cubic centimeter, and about one ten thousandth the number of stars in the observable universe. I’m creeping up on two quintillion nanoseconds.

Not entirely coincidentally, the Unix epoch corresponds to the moment at which the integrated circuits were passed the Moore’s Law baton. Steve Jurvetson has kept this plot continually updated since 2008:

The cost of a bit operation per second since the dawn of the Unix epoch has gone down by about a factor of a trillion, which of course, is starting to produce emergent phenomena. The ability to succeed at college level exams emerges, for example, after about a mole of training compute flops.

More moles of training flops are projected to lead to a number of outcomes, some quite unsettling.