Re: interoperability

2006-01-09 Thread Clive D.W. Feather
Rob Seaman said: The question of delivering wall clock time is a trivial elaboration on first delivering common international business time. (I'm trying on different terminology than civil time until I hit one that sticks.) I don't accept that the concept exists. The international business

Re: interoperability

2006-01-09 Thread Steve Allen
On Mon 2006-01-09T08:20:40 +0100, Poul-Henning Kamp hath writ: beginning (SI seconds are constant length). Yes, SI seconds are constant length, but the ghost of my general relativity teacher prompts me to assert that my SI seconds are not equal to your SI seconds because we are in different

Re: interoperability

2006-01-09 Thread Clive D.W. Feather
Rob Seaman said: I have heard no response to my discussion of techniques for achieving synchronization - of the difference between naive fall back hours and 25 hour days. But how in practice is it envisaged that a scheme for migrating time zones versus TAI would work, precisely? In the short

Re: interoperability

2006-01-09 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Steve Allen writes: On Mon 2006-01-09T08:20:40 +0100, Poul-Henning Kamp hath writ: beginning (SI seconds are constant length). Yes, SI seconds are constant length, but the ghost of my general relativity teacher prompts me to assert that my SI seconds are not equal

Re: interoperability

2006-01-09 Thread Rob Seaman
On Jan 9, 2006, at 12:06 AM, Poul-Henning Kamp wrote: You yourself defined stage one as TAI with some constant offset yourself, you can't change definition in the middle of the discussion. I was attempting to describe your position. In point of fact, I agree with Tom Van Baak: You cannot

Re: interoperability

2006-01-09 Thread Rob Seaman
On Jan 9, 2006, at 12:23 AM, John Cowan wrote: This is like the day is light and night is dark statement: there is, at any given location, one and only one sunrise per (solar) day, no matter what clocks say. Communication prospers when people's clear meaning is not subjugated to petty

Re: interoperability

2006-01-09 Thread Rob Seaman
On Jan 9, 2006, at 1:01 AM, Clive D.W. Feather wrote: We go through such discontinuities twice a year in most years. Only the uninteresting daylight saving jumps. UTC remains without discontinuities above the level of a leap second. If UTC weren't equivalent to what I call civil time, the

Re: interoperability

2006-01-09 Thread Rob Seaman
On Jan 9, 2006, at 1:22 AM, Clive D.W. Feather wrote: At some point, probably around the time that we're seeing an hourly shift every year, people are going to have to divorce second from day, or at least re-negotiate the terms of engagement. By what magic do we believe the issues involved

Re: interoperability

2006-01-09 Thread John Cowan
Rob Seaman scripsit: This is like the day is light and night is dark statement: there is, at any given location, one and only one sunrise per (solar) day, no matter what clocks say. Communication prospers when people's clear meaning is not subjugated to petty grammarians. My point was that

Re: interoperability

2006-01-08 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Rob Seaman writes: On Jan 8, 2006, at 9:09 AM, Poul-Henning Kamp wrote: Doing so would once and for all have to divorce earth orientation from that unified time scale, leaving it to governments to align civil time with daylight as they see fit (just like today).

Re: interoperability

2006-01-08 Thread Tom Van Baak
Without further debating the meaning of civil time, consider the implications of this two stage system. The first stage conveys TAI or something related to it by a constant offset. The second stage at any location (correct me if I misunderstand you) would be a secondary clock disseminated

Re: interoperability

2006-01-08 Thread Rob Seaman
On Jan 8, 2006, at 4:04 PM, Tom Van Baak wrote: You cannot divide timekeeping, time dissemination, into neat stages. Again. My point is strengthened. This being the case, a requirement on one flavor of time transfers to others. We will not solve the problem of creeping complexity and

Re: interoperability

2006-01-08 Thread Daniel R. Tobias
On 8 Jan 2006 at 15:04, Tom Van Baak wrote: You cannot divide timekeeping, time dissemination, into neat stages. In the 1960s if ten labs were told to offset their phase or frequency it affected only a handful of people or systems. Today when IERS announces a leap second, millions of

Re: interoperability

2006-01-08 Thread Tom Van Baak
You cannot divide timekeeping, time dissemination, into neat stages. In the 1960s if ten labs were told to offset their phase or frequency it affected only a handful of people or systems. Today when IERS announces a leap second, millions of machines, systems, and people are affected.

Re: interoperability

2006-01-08 Thread Rob Seaman
On Jan 8, 2006, at 6:41 PM, Tom Van Baak wrote: am not sure I like the idea that eventually my car, traffic lights, airlines, television, and my thermostat will have to be reliably tied to the IERS in order to function properly. This is a general issue with the increasingly tight coupling

Re: interoperability

2006-01-08 Thread John Cowan
Rob Seaman scripsit: The question is: how precisely does this differ from the situation now or in the past? Whether by fiat or not, some common worldwide stage two clock must exist. Again, no it doesn't need to exist. We need a uniform time scale like TAI. And we need local civil time for

Re: interoperability

2006-01-08 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Rob Seaman writes: Sensibly designed operating systems keep time in the form of the first stage clock, Perhaps. We have no examples of this. Stage one would be TAI. As we have just been reminded, TAI is not ready for prime time. Stop. You yourself defined

Re: interoperability

2006-01-08 Thread John Cowan
Rob Seaman scripsit: Sure, and you can timestamp then on either timescale, because there is a 1 to 1 translation between the two timescales [1]. Perhaps I miss your meaning here, too. The event of migrating a time zone is a discontinuity just as with a leap second or leap hour. Sure. But

Re: interoperability

2006-01-08 Thread John Cowan
Poul-Henning Kamp scripsit: Windows have got it right now I belive, but it used to be that a file created and transmitted from Denmark at the end of the business day would be older than a file created at the start of business day in California, despite a strict ordering of the events. It's

Re: interoperability

2006-01-08 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Rob Seaman writes: As I pointed out close to five years ago, the ultimate long term remediation will likely involve redefining the length of the second: Rob, I think this shows how little you understand of the entire thing. Several SI units are defined relative

Re: interoperability

2006-01-08 Thread Rob Seaman
On Jan 9, 2006, at 12:03 AM, John Cowan wrote: Each locality decides when and how to adjust both its offset from TAI and its seasonal transition function (if any), just as it does today. Not just as today, see intervening messages. What we abandon is a universal time tightly synchronized to

Re: interoperability

2006-01-08 Thread M. Warner Losh
In message: [EMAIL PROTECTED] John Cowan [EMAIL PROTECTED] writes: : But how in practice is it envisaged that a scheme : for migrating time zones versus TAI would work, precisely? : : Straightforwardly. Each locality decides when and how to adjust both : its offset from TAI and its

Re: interoperability

2006-01-08 Thread Peter Bunclark
On Sun, 8 Jan 2006, Tom Van Baak wrote: between astronomical and atomic timescales. Could we rephrase that between geophysical and atomic timescales ? Astronomers measure it and have to compensate for it, not cause it. Reminds me bitterly of the widely reported loss of Mars Climate Orbiter