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Comment by coldpie | Hacker News Reader

Hmm. I understand that perspective, but I'm not sure I agree. It does seem to matter over a relatively short & realistic time scale. According to the Wikipedia page, there have been 27 seconds added since 1972, which is only 44 years ago. At that rate, that's about 1 minute per 100 years. We have many systems that have existed for several centuries and I think it's not unreasonable to start making plans for systems that may exist for millennia, where you're starting to talk about a 10+ minute offset at the current rate.

But I do think there is a valid argument that the infrequency of these events cause more issues than maybe one large adjustment 500 years from now would cause. Not sure where I land on this one.

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> since 1972, which is only 44 years ago

Thanks for making me a decade younger :)

Can you explain how a 10 minute offset would affect you in any way?

For 99% of the world today, high noon =/= 12:00:00. Nothing breaks because of this. The world continues to run.

I ran into this trying to view the meridian line at the Basilica of Saint Mary of the Angels in Rome.

I was told the sun would show up on the calendar in the floor at noon. As noon approached, I saw nothing. Then I figured it probably needed to be solar noon, so had to look that up and wait around until that time. Today, that will be 12:20pm.

Nothing would have broken had I missed this, and nothing of critical importance is running on a solar clock (I don’t think), but it still led to a discrepancy in what was expected and where I needed to be when, based on drift from solar noon.

The problem is that Earth's rotation isn't consistently faster. Some years leap seconds need to be added, some years they need to be removed. Would be far better to leave them alone, let them average out, and as the GP said let the people who care about this add the offset they need.

> Some years leap seconds need to be added, some years they need to be removed.

Is that true? Per Wikipedia:

> Since [1972], 27 leap seconds have been added to UTC, with the most recent occurring on December 31, 2016. All have so far been positive leap seconds, adding a second to a UTC day; while a negative leap second is theoretically possible, it has not yet occurred.

Either way, it's due in part to Earth's rotation slowing down, so the average drift would still be non-zero.

We've not had to apply negative leap seconds yet since leap seconds were introduced in 1972, but that wasn't the point.

The time period of the Earth fluctuates a lot [0] and actually in 2020 it was less than 24 hours, but not a large enough change to warrant a negative leap second. If you go back to the 1940s, we would had needed negative leap seconds if we had leap seconds at all then, and going back 150 years we would have needed multiple negative leap seconds every year for several consecutive years.

What we can say is that on average, it is close enough to 24 hours and the average over hundreds of years is even closer to 24 hours that it's not worth adding these extra seconds as you'd then need to remove them again later on.

[0] https://c.tadst.com/gfx/900x506/graphlength-of-day.png from https://www.timeanddate.com/time/negative-leap-second.html

You make a good argument for the opposite of your conclusion. If you’re planning a system that’s supposed to last for millennia, that system shouldn’t depend on the fiat of the International Earth Rotation and Reference Systems Service.

Let's just do leap minutes. If humanity survives long enough to witness a leap minute without destroying ourselves then that's ample compensation for the minor inconvenience.

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