February 27, 2020
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Decimal Time of Day

FunkyFocus / Pixabay

The time system in the Earth Epic Calendar is itself somewhat unique and new though not unprecedented. This calendar uses decimal time, which was used in China, attempted during the French Revolution and introduced at other times since then.

The Earth Epic Calendar designates a  milliday as one thousandth of a day, and a sec as one one-hundredth of a milliday.  Thus the rule of one hundreds doesn’t quite apply as neatly with time, but it is surprisingly easy to visualize these times as they correspond quite closely to intervals of time we are familiar with today.  A milliday is a little more than a minute, and a sec is a little bit less than a second.

1 day = 1000 millidays (mday)
1 mday = 100 secs = 1 minute, 26.4 seconds
1 sec = 0.864 seconds

With a little practice, converting between millidays and secs and hours/minutes/seconds should be simple:

Millidays to hours:    hours = mday/1,000*24
Hours to millidays:    mday = hr/24*1,000

Let’s look at a typical time of day according to the Earth Epic Calendar:

547 mday

Note that each milliday is 1 minute, 26.4 seconds, which means that the last digit of the time changes roughly every 1 1/2 minutes.

Another way of looking at this time is realizing that the first digit represents decidays, thus one tenth of the day.  The second digit would represent centidays, or one-one hundredth of the day.

Since the first digit is 5, and five (therefore 500 mday) is halfway to ten, you can tell that the time is past noon.

Another trick is noting that each centiday is 14 minutes, 24 seconds.  As such, four of them roughtly equal one hour (57 minutes, 36 seconds to be exact).  So you can get a rough idea of what time of day it is on the Gregorian clock by dividing the first two digits–in this case 54–by four, and you’d get 13, meaning that it would be past 1:00 pm.

The French Revolution attempted to impose a decimal clock of ten decidays (two hours and 24 minutes each), and the clock had three hands to indicate the deciday, centiday and milliday. It probably failed partially because the deciday–an interval of two hours and 24 minutes–was not a convenient interval for useful planning. Nevertheless, there are a few Android apps that display the time in that way. The fact that it’s in digital format rather than using analog  lock hands probably makes it easier to read.

As stated in the Quarter and Day section of this website, the length of the day on Earth has changed over millions of years. Because of this, a standard length of time expressed as a decimal of the year (whose length has stayed constant throughout almost all of Earth’s history) would be a more accurate way of describing the length of time more than a million years in the past or a million years in the future.

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