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    Re: Navigation without Leap Seconds
    From: Frank Reed
    Date: 2008 Apr 18, 03:41 -0400

    Lu, in an earlier message, you wrote parenthetically:
    "although Richard Feynman claimed that a positron
    (positively charged electron) was in fact an electron moving backwards
    in time."
    
    This is miles from navigation, but I can't resist... Feynman's idea is
    considered uncontroversial today. A positron IS an electron going backward
    in time. But in the restricted sense that it carries no causality
    information. It's not a "time traveler" going back to kill its positronic
    grandfather and throw the universe into chaos. It's merely mathematically
    identical to an electron going backward in time. The future, with respect to
    causality, is the direction in which entropy increases, and fundamental
    particles don't know anything about that.
    
    And you wrote:
    "And that last sentence is the key to your question of "how would I
    practice celestial navigation if we didn't have leap seconds"   As long
    as I could convert my local time into Almanac time, it wouldn't matter,
    just as I adjust from local time to GMT."
    
    So you also agree that it would be no issue, right? The author of the time
    article suggested that the "vanishing breed" of celestial navigators would
    be upset over the abolition of leap seconds. I think that's incorrect. We
    would have little problem adjusting the rules in a world without
    leapseconds. But I'm still interested in some of the options as to how this
    might be done. Suppose I publish a nautical almanac today for the year 2058.
    How could I use it correctly for celestial navigation in that year? Adjust
    the input time?? Adjust the longitude at the end?? If I wait until 2057 to
    publish that almanac, it seems that the best approach would be the one Paul
    suggested: fold the longitude difference into the published GHA values.
    
     -FER
    
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