FACT:
The actual origin of METRIC TIME goes back to 1976 when Space Oddity creator Gary Davidson was trying to figure out how Star Trek's STARDATE system works.
In the Original series Gary noticed that the numbers following the decimal point were less than a day while those before the decimal were greater than a day.
As Gary was growing up in Canada at the same time that country was adopting the Metric System for units of measure (distance, weights [mass] and volume) the idea of applying the same theory to time was natural.
Many years later while developing Space Oddity he came to the conclusion that many different alien worlds forming a Galactic union might have a problem with adopting a time system specific to only one planet (Earth or anywhere else really), particularly when that system is rather ad hoc and difficult to calculate with.
While looking for a better system he came across his earlier notes on Stardates.
By the third Star Trek Movie it was obvious that any attempt to adapt his "metric" time to Star Trek was unworkable so Gary began to use it for his own series Space Oddity.
While trying to incorporate it into the continuity of the series he still found difficulty with the idea that other worlds would readily adopt a system with a single world's base.
In reworking METRIC TIME Gary came to the following conclusion... the only two measures of time which are freely convertable to distance are the LIGHT YEAR and the LIGHT SECOND.
But time is not as fixed as many would believe and YEARS not only vary from planet to planet even in our Star system but even on Earth you have both Sidereal years and Tropical years.
For this and many other reasons basing METRIC TIME on YEARS was abandoned but the LIGHT SECOND proved very promising.
Further research indicated that an International Standard was established for the SECOND on January 1, 1972. The SECOND was set as:
9,192,631,770 periods of the radiation corresponding to the transition between 2 hyperfine levels of the ground state of the cesium 133 atom
(NOW that sounds like a committee created time system!)
It was around this time that Gary realized METRIC TIME should be TRULY PROGRESSIONARY as well.
Setting ZERO SECOND at a fixed moment in history Gary had METRIC TIME simply calculate the number of seconds which had elasped since that moment and then moved the decimal point over until it divided those seconds which were less than day from those which were more than a day.
The result is a time system fully dependant on SECONDS but completely independent of Earth and Time Zones.
Gary wanted METRIC TIME to mean something to the audience, to actually be useful NOW.
He also knew that for it to work in the series SPACE ODDITY ZERO SECOND would have to mean something to the various member worlds of the newly formed UNITED ALLIANCE.
So he picked an event from SPACE ODDITY's TIMELINE for ZERO SECOND that had already "fictionally" occured and would be relevant as a historic milestone date.
In the TV series SPACE ODDITY ZERO SECOND was assigned to the moment that the invading aliens (MEGANITES) inflicted planetary genocide on an ancient established race, the MUSSANI, a people which had been resisting MEG expansion into this area of space.
The MUSSANI had previously formed a multi-world Alliance with many of their neighbouring planets and those worlds voted to commemorate the death of the MUSSANI by anchoring ZERO SECOND at the moment their world was vaporized.
The moment selected as ZERO SECOND coincides with 12:15pm daylight savings time London England, April 9, 1964
Which was also 7:15am in Toronto (and New York) or 4:15am Vancouver (and Los Angeles) April 9, 1964.
ZERO SECOND is expressed in METRIC TIME as 00000.00000.
