[Nottingham] [Misc] The Problem with Time & Timezones

Martin martin at ml1.co.uk
Thu Nov 12 17:31:23 UTC 2020


Here are a few further examples for what we do with marking time...

> What time is it?
> Where?
> When and where?
> And...?
> See the results of some heartfelt experience across the aeons:
> The Problem with Time & Timezones
> https://www.youtube.com/watch?v=-5wpm-gesOY
> That example makes my old hang-up of there being no year 'zero' in our
> present calendar for the Western world pale into inaccuracy compared to...
> And then there are database timestamps...

TLDR: We have LOTS of arbitrary idiosyncratic calendars throughout all
the ages!

For our *Common Era* see:

"Common Era (CE) is one of the year notations used for the Gregorian
calendar (and its predecessor, the Julian calendar), the world's most
widely used calendar era. Before the Common Era or Before the Current
Era (BCE) is the era before CE. BCE and CE are alternatives to the
Dionysian BC and AD notations respectively. The Dionysian era
distinguishes eras using the notations BC ("before Christ") and AD (anno
Domini, "in [the] year of [the] Lord"). The two notation systems are
numerically equivalent: "2020 CE" and "AD 2020" each describe the
current year; "400 BCE" and "400 BC" are each the same year. The
Gregorian calendar is used throughout the world today, and is an
international standard for civil calendars"

We also have:

*Holocene calendar*

"The Holocene calendar, also known as the Holocene Era or Human Era
(HE), is a year numbering system that adds exactly 10,000 years to the
currently dominant (AD/BC or CE/BCE) numbering scheme, placing its first
year near the beginning of the Holocene geological epoch and the
Neolithic Revolution, when humans transitioned from a hunter-gatherer
lifestyle to agriculture..."

(Avoids the confusion of negative years and no year zero!)

And more applicable for our world of computers and easier software:

*Unix time*

"... the number of seconds that have elapsed since the Unix epoch, minus
leap seconds; the Unix epoch is 00:00:00 UTC on 1 January 1970 (an
arbitrary date); leap seconds are ignored,[4] with a leap second having
the same Unix time as the second before it, and every day is treated as
if it contains exactly 86400 seconds.[2] Due to this treatment Unix time
is not a true representation of UTC."

*Decimal time*

"Decimal time is the representation of the time of day using units which
are decimally related. This term is often used specifically to refer to
the time system used in France for a few years beginning in 1792 during
the French Revolution, which divided the day into 10 decimal hours, each
decimal hour into 100 decimal minutes and each decimal minute into 100
decimal seconds (100000 decimal seconds per day)"

*Julian day*

"Julian day is the continuous count of days since the beginning of the
Julian Period and is used primarily by astronomers, and in software for
easily calculating elapsed days between two events (e.g. food production
date and sell by date).

... whole solar day in the Julian day count starting from noon Universal
time, with Julian day number 0 assigned to the day starting at noon on
Monday, January 1, 4713 BC, proleptic Julian calendar (November 24, 4714
BC, in the proleptic Gregorian calendar), a date at which three
multi-year cycles started (which are: Indiction, Solar, and Lunar
cycles) and which preceded any dates in recorded history..."

Choose your calendar!

*List of calendars*



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