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Comment by alecbz | Hacker News Reader

You also said:

> It sounds like Meta wants to change the definition of time for everyone just to make their programming a little easier. I find the very premise just out right ridiculous. ... Meta is just trying to make their problem someone else's problem.

Meta's argument is: we should get rid of leap seconds because even though they're helpful for astronomers, they're bad for everyone else.

Your counterpoint was: Actually leap seconds are _also_ bad for astronomers.

Which implies then that Meta is even more right to suggest that we get rid of leap seconds, because it seems like they help nobody.

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I can see how you'd read it that way, but my point was that they were not invented for astronomers, with the implication being the author didn't research the topic thoroughly enough to be making recommendations.

Astronomers have been one of the groups most vocal in favor of retaining leap seconds: https://www.nature.com/articles/423671a

Astronomers may just understand that the problem exists: [the ITU group’s chairman] says he needs more input from people who use universal time. “Many people don't even know that leap seconds exist,”

The decision to ignore leap seconds reminds of the decision by Russian and some other orthodox churches to ignore changes introduced by Gregorian calendar. The decision saved them some internal political problems, like the need to decide which saints will have their celebrations missing, but now the Orthodox Christmas is moving to summer with the speed of about 1 day per 100 years. Eventually somebody will have to deal with this, but not now - there’s a lot of time - same thinking.

Meanwhile, if you leave in a Gregorian country you can have your Christmas tree for free on Orthodox December 12th…

Orthodox Christians in the Southern Hemisphere already celebrate Christmas in summer, as do other Christians.

#borealocentrism

> borealocentrism

Guilty as charged. Thinking of that - there could be no more Russian winter as we used to it at all, even in the Northern hemisphere. My friends are now growing apricots in the Russian temperate zone. Apricots! - in the place there the “Baptismal Frosts” (to happen each year just before Christmas) used to kill all such fancy vegetation.

#climateasitwasbeforechangecentrism

> Eventually somebody will have to deal with this

The Islamic calendar drifts by about 10 days a year, and Muslims seems to be able to cope fine with their holidays not consistently being in the same season.

Well to be fair, I don't think the Muslim calendar is _meant_ to have any solar correspondence anyway. But more importantly the holidays, is the use of the calendar in having a natural sense of time (that is, corresponding with the seasons / sun). Which is why most Islamic countries use the Gregorian calendar for civil purposes (or so claims Wikipedia, at least).

Orthodox Christian countries also use the Gregorian calendar for civil purposes.

Many Islamic countries do in fact use the Gregorian calendar for Civic purposes, at the very least Egypt does which I can confirm by virtue of living here.

I'm not sure Orthodox Christians celebrate Christmas with a tree. At least in Russia the tree is mounted for New Year celebration and it lasts till Orthodox Christmas for granted. Actually it usually lasts to the so-called Old New Year - New Year in Old Style (meaning Julian Calendar before introduction of Gregorian one by Bolsheviks).

Far from being "most vocal", that 2003 article has a single quote from a single astronomer whose only warning is:

> If the change is implemented, “the old meaning of time will become ambiguous,” warns Steve Allen, an astronomer at the Lick Observatory in Santa Cruz, California.

This does seem like a problem that is solvable.

In 2015 the ITU (mentioned in that 2003 story as studying the problem) announced:

> The ITU World Radiocommunication Conference (WRC-15), currently in session in Geneva from 2 to 27 November, has decided that further studies are required on the impact and application of a future reference time-scale, including the modification of coordinated universal time (UTC) and suppressing the so-called “leap second”

https://www.itu.int/net/pressoffice/press_releases/2015/53.a...

In 2012 they also decided to defer:

> ITU Press Release of 19 January 2012 - ‘ITU Radiocommunication Assembly defers decision to eliminate the leap second’

https://www.itu.int/en/ITU-R/Documents/ITU-R-FAQ-UTC.pdf

> a single quote from a single astronomer whose only warning is...

It's not a quote, but the article also has Allen saying that "it could cost between US$10,000 and US$100,000 for each telescope to correct the problem, and that corrections will be tricky to implement."

It also has another astronomer claiming problems: "But separating time from rotation would mean that telescopes would no longer function properly, according to Patrick Wallace, an astronomer at the Rutherford Appleton Laboratory in Oxford, UK. Most telescopes with a viewfinder wouldn't be immediately affected, but instruments that track satellites and other moving objects could feel the effects within a few years, Wallace warns."

I found a few more details: https://news.ycombinator.com/item?id=32232564

It sounds like FB/Meta is correct in saying that Astronomers did object. I'd suggest (like Mata does) those objections are not especially important considering the trade-offs though.

> If the change is implemented, “the old meaning of time will become ambiguous,” warns Steve Allen, an astronomer at the Lick Observatory in Santa Cruz, California.

I'm with Allen. It's fine to drop leap-seconds; but then it's not UTC any more, it's a new time scale, and it needs a new name.

We've made this mistake before: in fact GMT has been redefined many times, and as a result the time interval between two GMT timestamps depends on which versions of GMT the two timestamps use, and so on the dates of the timestamps.

Allen has an instructive page on time scales here: https://www.ucolick.org/~sla/leapsecs/timescales.html

Astronomers use time for at least two different thing. For recording the time of events and observations, astronomers usually use the julian day, and for that leap seconds are a big pain. However, for precisely pointing a telescope without a viewfinder, you need the local sidereal time. The local sidereal time is fairly straightforward to (approximately) compute from UT1, the current date and your longitude. And leap seconds keep UTC within 1 second of UT1, so you can just use UTC.

But, for the latter problem, a better solution would probably be to have a service similar to NTP, that gives the current Greenwhich sidereal time, rather than UTC. Then it could be corrected more often than the current leap seconds. That doesn't solve the problem for existing telescope systems though.

In that case I don't think I understand what you mean by:

> Meta is just trying to make their problem someone else's problem.

It sounds like you agree that leap seconds themselves are a problem for people besides Meta?

Leap seconds are a "problem" in that they represent work and effort. That doesn't mean we need to discard them; they serve an important purpose.

I agree with gmiller here: https://news.ycombinator.com/item?id=32229049 that the whole thing smells like Facebook's engineers wanting to save themselves some work, at the cost of generating more problems for the future.

This kind of garbage attitude is why we have climate change, covid-19 and so many other things wrong with the world. Befitting that this one came from facebook.

I... What?

It's not Facebook. Even the examples of the post include non-Meta. It's not "some work". It's how we conceptualize time moving linearly, and that logic encoded on software.

People just want a reason to dig on Meta.

What important purpose do they serve?

I read this as a reply to sibling comment ("People just want a reason to dig on Meta"). It works surprisingly well in that role.

    It sounds like you agree that leap seconds themselves are a problem for people besides Meta?

They are a problem many people have already developed solutions to.

You have one of my favorite comments on this entire thread - so I'm interested in your thoughts on who leap seconds are useful for, if not Astronomers (and clearly not Meta).

They are useful for ordinary people. Without them, at some point in the future people would go to work at 8am at sunset and go to bed at sunrise. Leap seconds are a way for everyone to agree to shift their schedules by 1 second to stay in sync with solar time. It's subtle enough that most people don't even know they exist, nor will it have an effect on most systems. Larger jumps would be much more difficult to ignore, and smaller jumps would be more frequent.

How long from now are you talking about? Eyeballing it, I think it would take us about a thousand years to get off by an hour?

In the worst case, you would get 2 leap seconds per year. So in the worst case, 1800 years.

However, in the past 50 years, we've only had 27. So at the current rate, probably more like 6667 years to be off by an hour.

Of course, if the earth's rotation changed speed by so much that 2 leap seconds per year wasn't enough, we'd find a way to cram more in. In fact, in that case, the case for leap seconds would probably get stronger.

I would absolutely take the cost of work schedules being adjusted by an hour once every 6667 years over the cost of 6667 years of programmers having to deal with leap seconds and everyone else having to deal with the fallout of any bugs from that.

How long has the 9-5 even existed? Less than 200 years? At no point in 6667 years would anyone notice any consequences of the drift, culture and work schedules change so much faster than that.

> How long from now are you talking about? Eyeballing it, I think it would take us about a thousand years to get off by an hour?

The Julian calendar being off with regards to leap years wasn't a problem… until it was. And then someone had to fix it:

* https://en.wikipedia.org/wiki/Gregorian_calendar

We change our clocks twice a year by an hour I think we could handle an hour every millenia.

And, by some accounts, every time we do, auto deaths and other bad things increase for some period after the change. Not to mention the weeks of bitching on either side of the change about how bad/great the time change actually is.

One second every thousand years.

Do you mean one hour?

Yeah, one hour. Whoops.

> Yeah, one hour. Whoops.

I think your comment is a precursor to what would happen if we tried to get a one-off event right…

Right I'm sure we'll forget.

The physical effort of setting a clock is not the issue. Switching to "leap hours" would involve a good part of the world living with about 9am sunrise (or a 3:30pm sunset) for hundreds of years. It'd be a really hard sell to say that's actually better. DST is adjusting to the amount of daylight available, so there's not much of a negative impact. Systems that need to be more accurate just set their time zones to UTC. And one second every year or so is far within the accuracy of a typical computer clock, so anything that needs something better is already going to have a complex time synchronization system.

Yeah how ever will they live with having to wake up slightly earlier or later for their entire lives.

> earlier or later

My understanding was that leap seconds are only ever added. It’s not like this averages out over time. The problem is that because they are only added the effect is cumulative and eventually some future generation will be eating lunch at 00:00:00.

There is a provision for negative leap seconds. In practice, this has never happened.

Thanks, I skimmed the wiki and it sounded like they could only be added.

Hasn't happened, but it may actually happen in the next half-decade or so. If not, it's almost guaranteed to happen ~25 years from now.

So what is it about a system where everyone and every business adjusts their schedule slightly (I guess independently) of each other that is better than the leap second system we have now. Which, as I said earlier, is essentially the same thing, but done in a standardized way.

Timekeeping at the abstraction level where business hours exist is a lot more tolerant of 40 seconds of error than at the abstraction level where timekeeping primitives are implemented.

> a good part of the world living with about 9am sunrise (or a 3:30pm sunset) for hundreds of years

So no real change to the status quo?

For humans, it's no worse than folks today who live on a time zone boundary and cross it often. You might argue that for humans, the local solar time should be computed as a continuous function of longitude, leap seconds can be managed there, and we get rid of the concept of a time zone.

Computers are another story though, perhaps in the past "a typical computer clock" could be on the order of seconds off and be fine. When computers start to control things like wireless networks (cellular is a problem today, time accuracy is a design factor in evolving Wifi as well), those seconds turn into microseconds very, very quickly. The whole point of the article is to reduce unnecessary complexity in the existing complex time synchronization systems.

If you're running large infrastructure, the next leap second is going to cause an outage somewhere in your org, and the cost may be very large.

> Switching to "leap hours" would involve a good part of the world living with about 9am sunrise (or a 3:30pm sunset) for hundreds of years.

Can we switch to leap minutes instead? In the worst case it would mean to adjust the time once in 30 years, which means that astronomers and software engineers would have to deal with this problem no more than 3 times in a century. Fair enough IMHO.

> We change our clocks twice a year by an hour I think we could handle an hour every millenia.

And how often does time code mess that up? We have leap years regularly every ~4 years, and how does time code mess that up?

And you think that a one-off event is going to go smoothly?

The "ordinary people" really don't care about leap seconds. Like really, really not.

It's less than a minute in a life span. Just skip summer time once every millenium something.

This isn’t what would happen. Even we had a huge number of inexplicably needed leap seconds (there are 3600 seconds in an hour), local offsets would just change, for the same reason that people on the other side of the planet have a different time on their watch than you do. And if for some reason we proved incapable of doing that, then social conventions on when the work day started would shift relative to the local time. There just is no danger of people going to work at sunset.

I’m not saying that abandoning leap seconds is a good idea, just that abandoning them wouldn’t consign future generations to whacky schedules.

Their point is that Meta's argument is a straw man.

It's not really a straw man because Meta's not really attacking that position, they're ceding that point.

Like a straw man would be Meta saying "astronomers think that leap seconds are helpful but in fact they're not useful for anything!"

Here, if anything, Meta is attempting to steel man leap seconds a bit by saying "look, sure, leap seconds are at least useful for some things, like astronomy, but they're still not worth it overall". And GP is claiming that it's not a very good steel man because even astronomers don't like leap seconds.

But Meta's not actually ceding the point. They're essentially arguing that (1) leap seconds are an esoteric concept that only astronomers care about, and that (2) we shouldn't care about their esoteric concerns, so (3) we should therefore dispose of leap seconds.

The GP's point is that astronomers find leap seconds annoying too, so Meta's argument is based on a faulty premise.

Ok sure, I don't think I quite got that from what GP wrote, but I can see that as a valid argument: "There are actually valid uses for leap seconds, but just not within astronomy. Meta's claiming that leap seconds were made for astronomy so that we assume that's why they exist and ignore the other real reasons leap seconds exist and the benefits they provide."

They do not provide any.

Unless it is "programmers' employment assurance".

Yup, that's precisely how I interpreted GP's comment.

No. Astronomers deal with the problem leap seconds pretend to do with their own, more precise methods.

If the actual leap seconds do not benefit astronomers, and do not benefit anyone else, they are purely a tax on us all.

Abandon leap seconds in UTC, and literally everybody is better off. Even astronomers, who would go from managing 3 time systems to just two.

Astronomers whose software uses UTC and isn’t able to change to UT1, and who don’t need precision less than 1 second, but more than 3-5 seconds or so will be worse off. This seems like much less net inconvenience than what the tech industry has to deal with when it comes to leap seconds.

I hear the argument that we have to deal with this eventually to keep time in track with mean solar time, but the adjustments are so small that I don’t see any real impact on regular people.

You could very likely fund fixing the software of every astronomer on the planet for less than the cost of one outage caused by adding/removing a leap second when you look at Meta + Google + a few telcos.

> If the actual leap seconds do not benefit astronomers, and do not benefit anyone else, they are purely a tax on us all.

May as well dispense with the calendar entirely and just measure time in powers of ten.

An day is about 80 kiloseconds, and a year about 30 megaseconds.

Maybe many gigaseconds into the future our descendants will learn about old Earth time keeping in school, along with Roman numerals and the imperial system.

Yes, you will certainly persuade 100% of the world to rewrite all their code to your thing, and buy all new equipment with your thing in ROM.

> The GP's point is that astronomers find leap seconds annoying too

That just means that Meta is even more correct.

So you would be arguing that meta was being to charitable to the opposing side, and is even more correct than they originally appeared.

It isn't. Metas argument is valid even ignoring astronomers.

I like meta-bashing as much an any other facebook hater, but their point is that leap seconds are by definition used to keep UTC in almost sync with earth rotation and their argument is that it is not something useful to do.

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