[LEAPSECS] Straw men

Ian Batten igb at batten.eu.org
Tue Jan 10 02:33:12 EST 2012

On 10 Jan 2012, at 0541, Rob Seaman wrote:


> And yet many arguments here have proceeded from the observation that civilians rely on complex modern infrastructure.

That's a geek argument, if I might make so bold. Just because A relies on B doesn't mean that the consumers of A have any need to worry about B, and particularly not about the entirety of B. Your SatNav may rely on the full panoply of celestial mechanics, general relativity and caesium-rubidium clocks, but someone who just wants to find their way from Mill Hill Broadway to Dulwich East can have a mental model that the device contains a midget taxi driver with a good sense of direction and "The Knowledge" and they will be able to use the device perfectly happily. Once you have a sufficiently tall pile of abstractions, users of the top layer don't need to know anything about the lower layers in anything more than the vaguest detail, and potentially not at all. I know, in outline at least, how GPS works, down to the structure of the C/A and PPS code streams and a sense of how a covariance matrix contributes to the error analysis. I'm pretty sure that my ability to type in a postcode and then listen to the directions is not affected in any way by this. "People like us" like to think that you need to understand a piece of equipment in order to use it effectively, but it simply isn't true, and I'm sure there are technologies in existence which you use which you have far less knowledge of the operation of than you think "civilians" should have of timing and navigation.

> For instance, a lot of telecommunications depends on satellite technology, hence the sponsorship of the Future of UTC meeting by the American Astronautical Society and the American Institute of Aeronautics and Astronautics. Modern technology depends on both kinds of timekeeping. A conceptual model recognizing the distinction is necessary.

But Civil Time does't care. It just needs to be monotonic, roughly uniform, and roughly in line with mean solar time, with the minimum of effort for its consumers.


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