over thousands of years of cultural indoctrination and 'just plain superstition', mankind invented a year of 365.25 days, a day of 24 hours, an hour of 60 minutes etc... now there are all sorts of cultural superstitional societal reasons for this set of values, including the shipping industry's invention of Arbitrary Time Zones.But let's look at the real evidence.
The Earth goes round the Sun ONCE a year.
The Earth rotates ONCE a day.
We know when the Sun is in its highest point in the sky on each day i.e. noon is always known despite the shifting tilt of the planet through the year.
We know when the low-points and the high-points, the Solstices, are (June 21-22 and Dec 21-22).
What else do you need but a decimal day and a decimal year?
For example: 12 noon on June 21 (the longest day i.e. highest elevation point of the sun in any given year) would be 0.50000 in Global Time, 12 noon on Dec 21 would be THE START of each new year. The HIGH POINT of the sun in the sky should always mark the 'real start' of that day.
Time is GLOBAL now that technology surrounds the Earth, no matter where you are (in longitude and latitude) on the Earth, you can always guide the marking of NOON. Every 'clock' could 'synchronised with this global noontime' so that local time is always marked on every watch no matter what longitude one is at or moves through.
