字幕表 動画を再生する 英語字幕をプリント - I'm just outside the town of Gudhjem on the northeast coast of Bornholm in Denmark. It's a little out of the way. To get to this point from Copenhagen I had to drive across the Oresund bridge and through Sweden... GPS: "Take the second exit and stay on 'Dag-hammer-schultz-vag'." ...then take a 90 minute ferry ride, and then drive across the island. But this island, or more specifically, a north-south line across this island starting right here, is the only bit of Denmark that is exactly 15 degrees east of Greenwich in London, exactly 1/24th of the way around the Earth. which means that the sun is highest in the sky here exactly one hour before Greenwich. This lines defines Central European Time for Denmark. To explain why there's a problem with that, we need to talk to someone back where I started. - The observatory we are seeing here used to be the official timekeeping of Denmark, so it actually provided what time the national time in Denmark was. In 1893 a law was put in effect in Denmark, at which point the time of Denmark was synchronised with international time zones. So at that point in time, communications, transportation across borders had become so fast, so international that it was becoming a problem that every country had its own national timescale. - Back before railways and modern telecommunications, every town and village in the world ran on its own time. 12 o'clock was when the sun was highest in the sky, on average, wherever you were. That's called mean solar noon. Once the world started to move fast enough, though, every town and village having its own time became a problem. And steadily over decades, governments agreed that the official legal time would be the same in each region, in each time zone. And that each time zone would be offset by a round number compared to the time at Greenwich in London. The closest round number to Copenhagen was one hour, 15 degrees east, and so Denmark chose that. The clocks everywhere in the country were changed to agree with mean solar noon at this line. But then along came the Information Age, and it turned out that wasn't quite good enough because the Earth wobbles. - Earth wobbles a bit in its rotation and that means that it's not exactly the same all year round, and more than that, Earth rotation also slows a bit over time because of tidal forces from the Moon. If we were actually, in Denmark to follow our own time, like our mean solar time, we would be off with some hundredths of a second, and this would actually make it difficult for Danish financial companies, for instance, to actually trade on stock markets. - Once humanity had got the ability to track the Earth's rotation precisely we found out that noon drifts a little, by a tiny and different fraction of a second each day. And when computers, and clocks, and scientists around the world need to be accurate to within that tiny fraction of a second, that's a problem. So the scientific community agreed to ignore the wobble and created Coordinated Universal Time, UTC, which doesn't care about the Earth's movement. To your phone, your computer and to your bank, to basically everyone apart from astronomers, a day is precisely 86,400 seconds. As measured by the average of a network of atomic clocks around the world. If you want to be really detailed, then on screen is the full formal definition of a day. And every time the Earth's wobble threatens to drift out of sync with our standard, we add a leap second to UTC, either skipping a second or counting a second twice to get UTC back in line with the annoyingly real Earth and stars. The catch is, [sighs] Denmark never updated its laws. - The official law in Denmark is defined by a law from 1893 which states that Denmark follows mean solar time. In reality Denmark follows the Universal Coordinated Time, the atomic clock time which is used all around the world. So I made a petition to Parliament in Denmark to try to change this law. Some Danish media took up this story and following that, a member of the Danish Parliament actually made a question to the minister, and the minister then said that he was actually interested in looking into this and maybe make changes to the law. - As I record this, the error is tiny, it's only about .04 seconds, but that's just based on when I happen to be filming here. By the time this video goes live, the error is predicted to be at about .06 seconds. By the end of the year, it'll be about a quarter of a second. I've written some code that will keep checking the clocks and automatically update the title of this video as we go. At least until the code breaks and I can't be bothered to fix it anymore. The error could get all the way to .9 seconds before a leap second arrives to correct it. But it's not like phones, and computers and stock exchanges here in Denmark follow Danish law. They don't pay attention to the stars. They all just use UTC instead, and ignore the outdated legislation. So does it matter? - I think that laws should in general be in accordance with reality [laughs] and if not you should at least decide that we want to keep it this way actively. Denmark does not have any official time laboratory, so we rely on the time services from neighbouring countries. This may put us at a disadvantage compared to other countries. - If everyone agrees to ignore a law, and the government doesn't care to enforce it, that's fine. As long as the government keeps deciding not to enforce that law and also to ignore the hypocrisy that government is ignoring its own laws. Fixing that shouldn't be the highest thing on the priority list, but it'd be nice to do it at some point. After all the United States moved to UTC in 2007 with the America COMPETES Act. And the UK... Ah. Er. [clears throat] Y'know, it's probably not a good time to bother the British government right now. It can wait. We've got time.