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Comment by freehunter | Hacker News Reader

I fail to see how this is an attack on science or on Europe. That's just hyperbole. Making time consistent to prevent having to add time or remove time just makes sense. Time is a unit of measurement. We don't redefine the foot just because the new king has 10" feet instead of 12" feet. Time being connected to the sun is a relic of the days before accurate time-keeping methods. One day should always be one day.

To rebut my own argument, I suppose one could say that noon should always be noon, regardless of how long the day is. The prevalence of daylight-saving time in the US might disagree with that though.

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> I suppose one could say that noon should always be noon ...

Yes, but by allowing our clocks to go out of sync with the natural time of noon, a relationship controlled by orbits rather than clocks, this proposal would prevent that. Over time noon (highest solar position in the local sky) would drift away from noon as given by a clock.

I especially like the part where this proposal's advocates dismiss those who use a sextant to locate themselves on the ocean. I personally required this clock consistency to navigate my boat during my around-the-world sail, after my hi-tech satellite receiver expired.

This is not to argue that there's only one good argument here -- both arguments are reasonable. Unfortunately, they differ in the most basic way.

If we stick to 86,400 seconds in a day and don't allow leap-seconds, eventually daylight will happen at midnight -- either that or we will require leap-hours or even leap-days (as happened in Europe during the transition from the Julian to the Gregorian calendars).

If we continue to allow leap-seconds, all sorts of chronological record-keeping will continue to be more complex than it needs to be.

As with all truly interesting problems, there's no easy answer.

How long would it take for noon to be mid-night (as in middle of the night)? Centuries? By then, one would hope we're dealing with the bigger issue of how to coordinate time between two or more different planets or solar systems. As it stands, a certain section of scientists have to do the translation between the length differences of Earth days and Martian days.

It does provide a nice discussion point.

> How long would it take for noon to be mid-night (as in middle of the night)? Centuries?

Much longer. But the practical difficulties would appear right away, when the time "error" is still measured in seconds. As I said earlier, both sides of this issue have perfectly valid points to make.

Right now leap seconds are added well under 1/year (and no negative leap seconds have been added). Let's just assume we need 1 sec/year.

Even to get 5 minutes out of sync, that's 300 years. A leap-hour would need thousands of years. I think it's a rather weak argument that we should worry about noon being "out of sync" for thousands of years in the future.

> I think it's a rather weak argument that we should worry about noon being "out of sync" for thousands of years in the future.

Not if you're on the open ocean and need to know where you are, as I was every day for four years during my around-the-world sail. In that case, "noon" had a very specific, and very important, meaning -- each second of clock error equals 1/4 nautical mile of position error (or 1,519 feet).

I emphasize that both sides of this issue have very reasonable arguments.

Then keep solar time as a timezone and switch into that mode when you really need solar accuracy. This is a rather extreme edge case.

And actually, it can easily, very easily, be done by hand, even if we stopped adding leap seconds to UTC. Just keep a log of leap seconds and then apply them to your UTC clock.

Sticking to celestial bodies for time seems pointlessly complicated to satisfy a few edge cases that can be handled in better ways.

I think a leap hour makes sense because it could be integrated into DST (it wouldn't be an actual leap hour; you'd just change your timezone offset). If DST still exists hundreds of years from now.

> Noon should always be noon

In other words, given a point on Earth (or any planet) and it's angle relative to the sun it orbits, when that point aligns exactly with and faces the center of the sun, it is noon.

Consider this: The way everyone refers to time is "X Units before noon", much like the 24-hour clock (no am/pm), except 0 is noon. The key is that X must be flexible, it should have no maximum, and no minimum.

edit: clarification

This is not literally true. The period between solar noons oscillates and varies up to tens of seconds away from precisely 12 hours, thanks to the differing orbital speed of the Earth between perihelion and aphelion. What you're referring to is "mean noon", true solar noon averaged over the course of a year. See "mean sun" : http://en.wikipedia.org/wiki/Mean_sun

More complications arise from the position of the Moon. The Earth's rotation is affected by tides (stronger when the Moon is at perigee), and by the Earth's orbit around the Earth-Moon barycenter. Precession of the Earth's rotational axis is also a factor. And many more astromechanical effects also subtly affect the timing of the apparent position of the Sun.

Locking our timekeeping to the actual position of the Sun actually proves to be an intractable problem. At some point, we need abstractions to simplify and assume that that the relation to the Sun is good-enough. Famously, the Julian calendar was good-enough for millennia until the relation to the sun drifted off true by more than 10 days. So arguing over leap seconds could be seen as rather trivial.

This is amazing stuff. Thanks! I agree that arguing over leap seconds is trivial. We're at a good enough point now, assuming leap seconds are handled correctly, such that accounting for those seconds keeps us on track.

reminds me of "relative time" Jews and Muslims (and Japanese, until 1872) use. This is a French wikipedia article I stumbled upon: http://fr.wikipedia.org/wiki/Shaot_zmaniot

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