Experts consider consequences of ‘leap second’ elimination | Hacker News Reader

Experts consider consequences of ‘leap second’ elimination

itu.int

49 pointsllambda35 comments

Finally!

The only consequence would be a very, very slow drift between the "wall clock" time and the time of sunrise/midday/sunset. Given that people living at +/- 30 minutes off from the sun-time (borders of current time zones) experience no problems at all, then we should have ~2000 years before the difference is significant - and by that time, hopefully, we'll be living on more than one planet and won't care that much about synchronising everything with the rotation a single large rock.

You are right; if we need about 1 second a year that is about 30 minutes in 2000 years. Lets agree to add a leap hour 2000 years from now - that will put us 30 minutes ahead so we can go 4000 years until we need to add another hour

Bad idea for things that use the sun to synchronize - solar panel servos, for example, or locator buoys that need a failover in case GPS satellites all decide to call it quits (There are such things for navies and commercial ships).

Wouldn't it be more efficient, and less error prone, for solar panel servos to have a sunlight/brightness input feedback mechanism, rather than time-of-day based position?

How long is any one buoy in service? 5 years? 10? will it really matter on that scale?

The sun moves 0.25 arcminutes in the sky every second, and has an apparent diameter of 30 arcminutes. Meaning that even after 50 years, if you (or your solar panels) look straight up at noon you'll still be pointed at the sun. So systems built to last for hundreds of years are the only situations where I could see it mattering.

Even less than that - it affects only systems that are both built to last for hundreds of years and have no maintenance or communications possible for hundreds of years and aren't smart enough to carry a bit of code to do an approximate adjustment themselves. Which should mean no systems at all.

The only one that comes to mind is Stonehenge.

Sun-tracking monoliths in general. We should really get around to building one of these near the seed vault at some point.

Keyword being "should".

Then those few super-delicate astronomical systems can sync up their own leap seconds.

Leap seconds are a terrible, idiotic thing because some people want to have their NTP servers lined up with sundials. There's no legitimate purpose for them in use for computer nor civil time.

Proposing a leap hour seems like the best way. That way we can nod to the people that feel the sun's position matters, while knowing that in thousands of years someone else can deal with the issue.

If some system is so disconnected that their direction/location can't be adjusted remotely every few years or so, then the current leap second data doesn't work for them anyways - they aren't scheduled far in advance, and that system won't get the info when a new leap second is announced.

By the way, do solar panel servos really have the proper sun-time set in them? I mean, if one panel is 200 feet west of another, is its clock set to be 2 seconds later?

Couldn't we just redefine the second by a tiny amount so it fits the day?

Unfortunately the day fluctuates, and is actually lengthening over time: http://en.wikipedia.org/wiki/Fluctuations_in_the_length_of_d...

We need at least one unit of time which is fixed and unchanging in order to do scientific calculations, and we have chosen the second to be that unit.

So, instead of adding or subtracting leap seconds, we adjust the speed of light (and every other physical constant that includes a time unit)?

Also, which day would become the new standard: the solar day or the siderial day?

That would be a really terrible approach. Time is the ultimate basis for practically every other quantity we know how to measure. The SI second definition is literally the last thing you'd want to mess with.

This (seconds being a universal unit of time regardless of planet lived on) is exactly the situation described in Vernor Vinge's (a CS professor) "A Deepness in the Sky".

We already have several time options without leap seconds, such as International Atomic Time [1] and GPS Time [2]?

Why can't people who want to avoid leap seconds just use those?

If we switch to leap-minutes or leap-hours they'll be rare enough that software bugs won't get exposed enough to get fixed - it'll be like Y2K every time.

[1] https://en.wikipedia.org/wiki/International_Atomic_Time [2] https://en.wikipedia.org/wiki/GPS_time#Timekeeping

Personally, I prefer xkcd time. http://xkcd.com/1047/

Seconds in a year: 75^4 seconds

Age of the universe = 15^15 seconds

Planck's constant: 1/30^pi^e

Why can't we use a sensible (moving forwards at a constant pace) time as a default for everyone, and have those rare astronomical systems use some special time options?

Both TAI and GPS time are offset from UTC by a noticeable amount, so switching to one of them would produce a large disruption, especially given that it would have to be done incrementally. Also, many people feel legally compelled to use UTC, so the only solution for them is to legally redefine UTC to have no additional leap seconds added in the future.

I wouldn't bother with leap minutes or hours either; instead we could just adjust timezones to create a virtual leap hour. It would effectively be a permanent version of daylight savings time (assuming that such a concept exists in 2,000 years).

By the time leap minutes will be a serious issue many humans will be living on planets other than Earth. Leap seconds are absolutely the wrong solution to the problem of trying to translate between some sort of absolute time and local time.

If you're interested in this topic, I recommend you peruse the archives of LEAPSECS mailing list ( http://six.pairlist.net/pipermail/leapsecs/ ), where experts have discussed some of the thorny issues over the years.

It's cool to see the ".int" TLD for once---by far the most obscure of the original seven (.com, .edu, .gov, .int, .mil, .net, .org, [and .arpa, if you're old]).

Whoa me too, in about 15 years of surfing the web I've never noticed any .int TLD. Not old enough for .arpa but this is cool. I would have not seen this without your pointing it out. Thanks for the life experience! ;) With mobile browsers these days most of the time the URL isn't even shown.. So I hope everyone can appreciate this

The European Union web page is europa.eu.int. That's the biggest one I can think of.

I do admit that one probably don't see that one a lot if you don't live in Europe.

> The European Union web page is europa.eu.int

You're a little out of date there, I'm afraid. They officially switched from europa.eu.int to europa.eu in May 2006, after the EU's successful campaign to get their own .eu TLD in 2005.

.arpa is used for reverse DNS lookups. The PTR record for the IPv4 address 1.2.3.4 is looked up at 4.3.2.1.in-addr.arpa.

And for enum lookups, e.g. +1-555-5678 becomes 8.7.6.5.5.5.5.1.e164.arpa.

I don't see the point in this, you can't dumb down the complexities of the real world just because it'll make some engineers happier.

That's not the issue, the issue is putting the complexity in the right place. There is immense value in having a simple, unambiguous measure of absolute time and date but because a few powerful scientists and engineers decided that very silly anal retentive issues were more important than fundamental ones we can't have that. Creating a map between absolute time and local dates and relative times is much easier than scattering the diffs relative to local time through every part of the system.

> you can't dumb down the complexities of the real world just because it'll make some engineers happier

Except that everything in science and engineering is about dumbing down the complexities of the real world so that it makes more sense to us.

While we are on it, can we also get rid of time zones and switch to 10-based (kiloseconds etc) time units?

This will suck for astronomers and anyone doing celestial navigation.

Can celestial navigation really measure stuff up to 1 second accuracy? Can astronomers anyway use the "wall-clock" time directly? Unless they're located in Greenwich, they anyway need to adjust for their exact location since it is not exactly in the middle of a time zone; after such changes they'd just automatically sync the relevant clock not to UTC but to some "Astronomical-UTC" time zone and that's it.

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