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Why the U.S. Wants To End the Link Between Time and Sun

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Re: Why the U.S. Wants To End the Link Between Time and Sun

#41

Post by MichaelGG »

lutusp wrote: post #19
freehunter wrote: post #9

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 re…

> 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…

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.

Re: Why the U.S. Wants To End the Link Between Time and Sun

#42

Post by lutusp »

freehunter wrote: post #36
lutusp wrote: post #19

Earlier quoted context omitted.

> 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…

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.

Re: Why the U.S. Wants To End the Link Between Time and Sun

#43

Post by lmm »

tg3 wrote: post #5
jackta101 wrote: post #2

This article is 7 years old and irrelevant. In fact a leap second was insert in June this year.

Interesting discussions can still be interesting even if the proposal was ultimately rejected. The fact that this was discussed, and that the reasoning behind it was to benefit "lazy programmers" makes it relevant to me. We should always be wary of fundamental shifts in the name of "safety", "security", or worse, sloth.

This is not a fundamental shift. It's a tiny piece of bookkeeping.

Re: Why the U.S. Wants To End the Link Between Time and Sun

#44

Post by lmm »

cwe wrote: post #30
jmvoodoo wrote: post #24

I'm definitely looking forward to this debate when/if we ever have a permanent mars colony. Will they still use earth/solar time? Use mars/solar time? Some compromise between the two? I imagine someone living on mars could give two shits if the earth/solar time was off by a few seconds, and I definitely don't want to be responsible for handling two entire time systems in my code.

40 extra minutes in a martian day definitely make things interesting. Going further, how will time work when we're stationed around Saturn's moons? We will probably need some universal units of time that work regardless of how long it takes you to rotate around the sun. (Stardates?)

Seconds since epoch is good enough for almost all purposes until you're moving at ~10% of the speed of light; they'll be fine for computer timestamps as long as acceleration and deceleration are gradual. So I don't think we'll need any new universal units of time, only new local units of time, and I'm not even sure about that. For mars, just extending the day until 24:40 = 00:00 seems reasonable enough. For Saturn's moons the sun is faint enough that keeping "earth time" is probably reasonable - whether it's solar day or solar night will make very little difference to most people's lives, I would think.

Re: Why the U.S. Wants To End the Link Between Time and Sun

#45

Post by lmm »

Codhisattva wrote: post #26
nextstep wrote: post #22

I read through nearly the whole article before I realized this was from 2005. What ever happened to this proposal?

We just had a leap second June 30 so the proposal must have been scrapped. edit to add link http://en.wikipedia.org/wiki/Leap_second#Proposal_to_abolish...

As per your link, it's not that the proposal's been scrapped so much as the decision's been postponed until 2015.

Re: Why the U.S. Wants To End the Link Between Time and Sun

#46

Post by freehunter »

kamjam wrote: post #27
patheman wrote: post #16

Earlier quoted context omitted.

"3:00 pm" is in the middle of the night, the time to wake up for work will always "change".. well, one time .. but do you !really! care about how the folks in +600 yrs measure time? I'd guess they invent some kind of "glacial-period-light-saving-time" by then...

I know it's a joke, but it's lazy programming/lazy thoughts like this that caused the issues with the systems in the first place :) Although I still don't fully understand why leap seconds caused such a problem - we can handle leap years and we can handle daylight savings, surely this is just another clock correction action such as these?

The problem with programming for a leap second is you don't know when a leap second will occur. Compare this to a leap year, which happen every 4 years, always. Leap seconds are sporadic [1]. Programming a clock to accept the time of 11:59:60 only on occasion is trivial in a web app, but slightly more complex in a firmware or high-reliability system like flight controls.

[1] https://en.wikipedia.org/wiki/Leap_second#Insertion_of_leap_... (see the chart at the side)

Re: Why the U.S. Wants To End the Link Between Time and Sun

#47

Post by agwa »

> leap seconds present a "risk to air travel in the future" because a glitch might shut down traffic-control systems.

This downright scary if true - a system that's not robust and fault tolerant enough to withstand a leap second bug without putting lives in danger is going to suffer from other bugs which will put lives in danger. Since software development practices actually tend to be very paranoid when it comes to air travel, I suspect this is really a scare tactic to garner support for abolishing the leap second.

> the U.S. has proposed adding in a "leap hour" every 500 to 600 years, which also accounts for the fact that the Earth's rotation is expected to slow down even further. That would be no more disruptive than the annual switch to daylight-saving time

I'm incredulous. Daylight savings time effectively works by changing your timezone offset from UTC. UTC itself doesn't change. Daylight savings time is actually very disruptive to programs, and the solution is to just use UTC for everything. A "leap hour" would presumably require changing the UTC-equivalent itself. I guarantee you that no one will actually code for such a rare event, which will make it a big and scary flag day which will get postponed repeatedly while everyone prepares (probably by bringing a bunch of legacy programmers out of retirement if software still exists by then). The only thing appealing about this is that we'll all be long dead by then.

Re: Why the U.S. Wants To End the Link Between Time and Sun

#48

Post by lutusp »

MichaelGG wrote: post #41
lutusp wrote: post #19

Earlier quoted context omitted.

> 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…

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.

Re: Why the U.S. Wants To End the Link Between Time and Sun

#50

Post by MichaelGG »

lutusp wrote: post #48
MichaelGG wrote: post #41

Earlier quoted context omitted.

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…

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.

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