Friday, May 27, 2016

What is the significance of January 1, 1970?

What is the significance of January 1, 1970?

UNIX, UTC etc. topic related. I also don't know the significance of UNIX. So I'm basically asking what is the big deal (because I don't know).
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2 Answers
Anders Kaseorg
Anders Kaseorg, MIT PhD student in CS; Cofounder of Ksplice, Inc.
6.1k ViewsAnders has 60+ answers in Computer Programming
January 1, 1970, 00:00:00 UTC is the Unix epoch. It’s just an arbitrary zero point from which all other dates and times are measured on Unix systems.

A more natural-sounding time like “the beginning of the first day of year zero” wasn’t used because of multiple problems:
  • there was no year zero (aaargh!);
  • there have been drastic changes to our calendar system since then (different in different parts of the world) that would unnecessarily complicate present-day date computations; and
  • representing offsets of about two millenia instead of a few decades would either cost several more bits or lose precision.
So the Unix programmers chose an epoch date closer to the present. See also Why does epoch time start with January 1, 1970?

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