[LEAPSECS] Leap seconds have a larger context than POSIX
sla at ucolick.org
Tue Feb 4 16:16:48 EST 2020
I have a growing bibliography with references that show the rush
toward atomic time was already underway at the 3rd CCDS meeting in
1963. At that meeting the delegates restricted themselves merely to
ask CGPM12 to authorize an atomic SI second before CGPM13.
The first time that the 4th meeting of the CCDS happened was in 1966,
but that meeting is not found in any official record. The meeting
ended with a vote to recommend that the CGPM should adopt an SI second
based on cesium, but the circumstances of that vote were deemed so
abusive that the entire meeting was nullified. That did not stop the
rush for an atomic second. During the next year subsets of the CCDS
members gathered for discussions at other meetings. When the second
4th meeting of the CCDS was held in 1967 they did recommend the cesium
second to the CGPM.
With that the push had turned to getting all radio broadcast time
signals to use the cesium second. Proponents of the cesium second
made demonstrably unrealistic presentations that minimized the
difference that would accumulate between Atomic Time and Universal
Time. When the issues were presented to agencies they recognized the
tension between the need to broadcast atomically-regulated seconds and
the need to provide earth rotation time used by navigators. The
recommendations from several agencies were to involve other agencies
in gathering together to study the problem.
In 1968 delegates heading toward the next meeting of CCIR Working
Party 7 gathered beforehand during a different meeting. There could
be no proceedings from that gathering, but an offhand remark in a
later report indicates they agreed that constructing a calendar out of
SI seconds would require forging an international agreement.
Altogether the meeting results were painting a picture that involved
many agencies comprised of many people and many countries, and also
much time to figure out a reasonable way to broadcast time using SI
Folks at the PTB took a different aim by introducing draft legislation
that the German government passed in 1969. The law made it illegal
for the German government to broadcast anything other than SI seconds,
and it would become effective in 1970. This seems to have pulled the
trigger on the CCIR process, for without some kind of quick action a
major nation would be broadcasting time signals using a different
scale than other nations.
Contributions and responses to questions from around 1969 make it
clear that some technical agencies were unaware of the political
constraints, and some bureaucratic agencies were unaware of the
technical constraints. Several memoirs make it likely that H.M.
Smith performed Herculean efforts to contain this dumpster fire of
spreading incomplete information and forge a final agreement which was
minimally objectionable to all parties.
In my home state of California the process that led to UTC with leap
seconds would have been illegal under the Brown Act that requires
public access to meetings. But in the full context that is not the
most criminal aspect of the process that led to the 1970 CCIR
After WW2 ended the ITU held a months-long meeting at Atlantic City in
1947 to discuss how recent advancements in radio technology would
affect international agreements for use of radio broadcasts. The 1947
proceedings include reports from many national agencies on the history
and technology of time determination and dissemination. The result is
an encyclopedic treatise on how they determined time, how they
broadcast time, what were the technological limitations, and what they
thought was important. It also produced a synopsis of all those
contributions which compared and contrasted the different methods,
indicated what were the goals of the CCIR, and described why the CCIR
recommendations were choosing particular methods already in use which
were generally deemed to be best practices.
The CCIR process that led to the 1970 Rec 460 produced nothing like
those 1947 proceedings. That is the criminal difference between CCIR
1947 proceedings and recommendations for broadcast time signals and
the 1970 recommendations. The process that gave us leap seconds was
not merely based in fear, it was also based on maintaining ignorance.
The closest thing to an admission that there might be reasons not to
use UTC as specified by CCIR was Recommendation 485. That allowed for
dates to be specified using either UTC or TAI, but ITU-R suppressed
TF.485 in 1997, just before the push to remove leaps from UTC began.
Based on all the history my impression is that it is not possible to
obtain any official improvements in the documentation for the rules
governing UTC nor for the way that authoritative information about
leap seconds and DUT1 is disseminated. Any such improvements risk
discussions that might delve into the origins and purpose of UTC.
Fear means that ignorance must be maintained for the sake of hegemony.
Steve Allen <sla at ucolick.org> WGS-84 (GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855
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Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m
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