Time would be so much simpler if we would just stick with Earth rotating around itself (day) and Earth rotating around the Sun (year.) Just know that there are about 365.25 days per year. That's all you have to remember, other than the standard metric prefixes.
What are we using now? Year, month, week, day, hour, minute, second... aye yay yay... what a mess!!! Not only do you have to know that there are about 365.25 days per year, but also:
-12 months per year (months vary 30 or 31 days, sometimes 28 or 29 days!!!)
-7 days per week (weeks don't even evenly divide into months!!!)
-24 hours per day
-60 minutes per hour (1440 minutes per day)
-60 seconds per minute (86400 seconds per day)
Similar to the distance mess (inch, foot (12 inches), yard (3 feet), mile E(5280 feet) )
Or the volume mess (teaspoon, tablespoon, ounce, cup, gallon)
https://en.wikipedia.org/wiki/Metric_prefix
Easiest method (forget weeks and months)
Date: (Year) and the whole part of (Day of Year)
Time: the fractional part of Day of Year
For example: date 2017: 21.5 is 2017 January 21 at 12pm.
Multi-days
Week based on day: Instead of a 7 day week, replace it with 1 deca-day (10 days), with about 36.5 deca-days per year. Maybe have 36 deca-days with 5 days remainder at the end of the year.
Week based on year: Instead of about 52 weeks a year, replace with 20 milli-years (about 7.3 days), with exactly 50 x 20 milli-years per year.
Month based on day: 3 deca-days (30 days) with about 12 deca-days per year with 5 days remainder days at the end of the year.
Month based on year: 10 months per year which would be exactly 1 deci-year (about 36.5 days.) Maybe have 10 36-day months, then 5 day remainder at the end of the year.
Or perhaps just dump the notion of weeks and months altogether and just go by x amount of deca-days or deci-years.
Sub-days
1 day is 86400 sec (24 hrs)
0.1 day = deci-day = 8640 sec (2.4 hrs)
0.01 day = centi-day = 864 sec (14.4 min)
0.001 day = milli-day = is 86.4 sec (1.44 min)
0.0001 = 100 micro-days = 8.64 sec
0.00001 = 10 micro-days = 0.864 sec
All sub-day units are evenly divisible with each-other with simple metric.
Calendars/Clocks can easily switch between the 2 systems.
00000(sec) 0.0 (days) 0.0 (24hrs)
08640(sec) 0.1 (days) 02.4 (24hrs)
17280(sec) 0.2 (days) 04.8 (24hrs)
25920(sec) 0.3 (days) 07.2 (24hrs)
34560(dec) 0.4 (days) 09.6 (24hrs)
43200(sec) 0.5 (days) 12.0 (24hrs)
51840(sec) 0.6 (days) 14.4 (24hrs)
60480(sec) 0.7 (days) 16.8 (24hrs)
69120(sec) 0.8 (days) 19.2 (24hrs)
77760(sec) 0.9 (days) 21.6 (24hrs)
86400(sec) 1.0 (days) 24.0 (24hrs)
Time duration is easy to calculate
If range remains in a year then use day of year (using fractional days)
For example, time between 2002 Jan 01 00:00hrs and 2002 Feb 01 12:00 hrs.
In metric time that would be 32.5 - 2 = 30.5 days.
If range spans multiple years then convert to years (using fractional years)
2002 Feb 01 12:00hrs = 32.5 day of year = about 2002.0890 years (32.5/365.25)
2003 Feb 20 00:00hrs = 51 day of year = about 2003.1396 years (51/365.25)
In metric time that would be 2003.1396 - 2002.0890 = 1.0506 (383.73165 days)
(leap year days need to be added in for some cases)
(timecards do use decimal hours)
Related links
https://en.wikipedia.org/wiki/Metric_time
https://en.wikipedia.org/wiki/Decimal_time
