[LEAPSECS] presentations from AAS Future of Time sessions

[Warner Losh]

On Jan 18, 2014, at 3:09 AM, Magnus Danielson wrote:


> On 18/01/14 10:41, Brooks Harris wrote:

>> On 2014-01-18 12:43 AM, Magnus Danielson wrote:

>>> On 18/01/14 08:57, Brooks Harris wrote:

>>>> On 2014-01-17 11:15 PM, Magnus Danielson wrote:

>>>>> 

>>>>> Let's face it, this lump of orbital debris we call our home planet is

>>>>> what we have as a reference and try to have common set of references.

>>>>> This is our "universe".

>>>>> 

>>>> 

>>>> The "universe" is a little larger than that for the astronomers. "Earth

>>>> time" would have made more sense.

>>> 

>>> You are missing my point, the word "universe" have different meanings,

>>> and when originally used for UTC it was used to mean a coordinated

>>> time for that "lump of orbital debris" and not for the "Universe".

>>> Thus, using a particular interpretation of the word as an argument is

>>> not very fruitful. It is just not very suitable choice of words, at

>>> least in english.

>>> 

>>> 

>> Both terms, "universal" and "coordinated", are laden with historical

>> connotations.

>> 

>> If you somehow refine the description of UTC I think you'd better rename

>> it.

> 

> There are ways to alter the definition of UTC and keeping within the concept.

> 

> If you want a different concept, then it's a different time-scale. The concept they are looking for already have an existing time-scale, but naturally they are free to contribute to the proliferation of time-scales by doing yet another one.


Proleptic UTC isn't really UTC, since it is a pure elapsed time in the Proleptic phase. It ceases to be an approximation of UT, UT1 or UT2 in any meaningful way.  But it is a damn convenient way to define things....

Warner