[LEAPSECS] Leap seconds, precision time, and technical progress

[Daniel R. Tobias]

On 26 Dec 2010 at 21:35, Poul-Henning Kamp wrote:


> In message <4D17A98A.7090104 at yahoo.com>, Michael Deckers writes:

> 

> >    The astronomical phenomenon that is used for determining

> >    the phase of UTC is the rotation of the Earth, and this

> >    is no longer one of the "fundamental vehicles" for

> >    synchronization because it is (currently) neither

> >    constant nor predictable to a sufficient degree.

> 

> Nor is it, for that matter, "universal" in any relevant meaning

> of the word.


Probably "Terrestrial Time" would be more logical as a descriptor, 
but that's already been taken for yet another different time scale 
not tied to the solar cycle.

Already, with various unmanned missions on Mars (and perhaps 
eventually manned missions or even permanent colonies), the need for 
a Martian time has been seen, and while they're still at a rather 
early stage of standardization of this without a full-fledged Martian 
calendar system (they just use standards that differ from mission to 
mission, with no consistently-kept numbering system), they do use 
Martian varieties of hours, minutes, and seconds that are a different 
length from the Earthly ones in order to fit in the Martian solar 
day.  Eventually, if they do establish a complete timekeeping system 
that's maintained in the long run, they'd have to tackle the question 
of whether the Martian seconds are "rubber" to match the solar day 
even if it varies (does the Martian day vary in the manner Earth's 
does?), or defined as a fixed length and possibly necessitating leap 
seconds from time to time.  At any rate, that system would be 
distinct from that of Earth, and the same would be true for whatever 
other planets might have human activity in the future.  Eventually 
there might be lots of different solar-based time scales for 
different planets, tied to calendar systems based on the local day 
and year, and they'd all be distinct from the "universal" scientific 
timekeeping which would be based on atomic clocks.  At that point it 
would be most logical for Earth to also have a solar-based system, 
and it would only be for historical reasons that the universal system 
used by mankind galaxy-wide happened to have units that approximate a 
fraction of the Earthly cycle.


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