Re: the tail wags the dog

2006-01-24 Thread Rob Seaman
On Jan 24, 2006, at 12:50 AM, Peter Bunclark wrote: I don't think Rob meant the above to be a complete course on navigation! ...although as a fan of Patrick O'Brian I am qualified not only to teach navigation, but also the violin and Catalan. You should see me in a Bear costume. Good

Re: the tail wags the dog

2006-01-24 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Rob Seaman writes: Quadratic despair still lurks, of course, since the month is lengthening for exactly the same reason as the day. Well, despair would be lurking if we tried to match the length of the month (a natural phenomenon) to an SI unit (such as the second).

Re: the tail wags the dog

2006-01-24 Thread James Maynard
Rob Seaman wrote: On Jan 24, 2006, at 12:50 AM, Peter Bunclark wrote: I don't think Rob meant the above to be a complete course on navigation! ...although as a fan of Patrick O'Brian I am qualified not only to teach navigation, but also the violin and Catalan. You should see me in a Bear

Re: the tail wags the dog

2006-01-24 Thread Ed Davies
James Maynard wrote: The problem is not that the SI second is not based on a natural phenonemon (it is), but that the periods of the various natural phenonema (rotations of the earth about its axis revolutions of the earth about the sun, revolutions of the moon around the earth, etc.) are both

Re: the tail wags the dog

2006-01-24 Thread Rob Seaman
On Jan 24, 2006, at 8:06 AM, Ed Davies wrote: James Maynard wrote: The problem is not that the SI second is not based on a natural phenonemon (it is), but that the periods of the various natural phenonema (rotations of the earth about its axis revolutions of the earth about the sun,

Re: the tail wags the dog

2006-01-24 Thread Rob Seaman
On Jan 24, 2006, at 7:21 AM, Poul-Henning Kamp wrote:I think the crucial insight here is that geophysics makes (comparatively) lousy clocksThe crucial insight is that the Earth is not a clock at all, but rather the thing being timed.and we should stop using rotating bodies of geophysics for 

Re: the tail wags the dog

2006-01-24 Thread Ed Davies
Rob Seaman wrote: All proposals (other than rubber seconds or rubber days) face the same quadratically accelerating divergence between clock and Earth. By rubber seconds you, presumably, mean non-SI seconds. What do you mean by rubber days? I'd guess you mean days which are

Re: the tail wags the dog

2006-01-23 Thread Clive D.W. Feather
Steve Allen said: The official time of the US for commerce and legal purposes is UTC(NIST). The official time of the US DOD is UTC(USNO). The official time of the Federal Republic of Germany is UTC(PTB). etc. The official time of the UK is GMT. -- Clive D.W. Feather | Work: [EMAIL

Re: the tail wags the dog

2006-01-23 Thread Steve Allen
. The legal time of the US is (in many more words) GMT. The officials who are charged by congress with the task of providing time provide UTC. The situation is exactly the same in the UK. http://www.npl.co.uk/time/truetime.html http://www.npl.co.uk/time/msf.html I reiterate that the tail wags the dog

Re: the tail wags the dog

2006-01-23 Thread M. Warner Losh
In message: [EMAIL PROTECTED] Steve Allen [EMAIL PROTECTED] writes: : The legal time of the US is (in many more words) GMT. : The officials who are charged by congress with the task of providing : time provide UTC. The legal time in the US is the mean solar time at a given meridian,

Re: the tail wags the dog

2006-01-23 Thread Rob Seaman
On Jan 23, 2006, at 9:33 AM, M. Warner Losh wrote: The legal time in the US is the mean solar time at a given meridian, as determined by the secretary of commerce ...and many may have seen Mr. Gutierrez shooting the sun with his sextant out on the Mall in front of the AS Museum :-) With all

Re: the tail wags the dog

2006-01-23 Thread Steve Allen
On Mon 2006-01-23T09:33:10 -0700, M. Warner Losh hath writ: (the term mean solar time isn't legally defined, but does have an accepted scientific meaning). Would that it were so, but I don't believe it because I've read the proceedings of the IAU general assemblies and related papers. I've

Re: the tail wags the dog

2006-01-23 Thread John Cowan
Rob Seaman scripsit: The legal time in the US is the mean solar time at a given meridian, as determined by the secretary of commerce ...and many may have seen Mr. Gutierrez shooting the sun with his sextant out on the Mall in front of the AS Museum :-) With all the words that have flowed

Re: the tail wags the dog

2006-01-23 Thread Peter Bunclark
On Mon, 23 Jan 2006, John Cowan wrote: Rob Seaman scripsit: that it can be reliably recovered from observations whenever and wherever needed (once you are located with respect to a meridian, of course). I don't understand this. You can't shoot the mean sun with a sextant, only the

Re: the tail wags the dog

2006-01-22 Thread Michael Sokolov
Steve Allen [EMAIL PROTECTED] wrote: The CGPM recommendation on the timescale everyone should use says UTC. UTC(insert your national time service here) is available in real time. TAI is the mathematical (really the political or diplomatic) entity upon which UTC is ostensibly based, but the

Re: the tail wags the dog

2006-01-22 Thread Nero Imhard
Michael Sokolov wrote: Steve Allen [EMAIL PROTECTED] wrote: TAI is the mathematical (really the political or diplomatic) entity upon which UTC is ostensibly based, but the practical and legal reality is the other way around. Has it occurred to any of you that *THIS* is the very root of

Re: the tail wags the dog

2006-01-22 Thread M. Warner Losh
In message: [EMAIL PROTECTED] [EMAIL PROTECTED] (Michael Sokolov) writes: : Steve Allen [EMAIL PROTECTED] wrote: : : The CGPM recommendation on the timescale everyone should use says UTC. : : UTC(insert your national time service here) is available in real time. : : TAI is the