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Comment by kmasters | Hacker News Reader

I agree its a little bizarre, but as for the length of days, changing to a metric equivalent wouldnt really require changing the length of a second would it?

We have a fixed system right now and when its off we just say this day is a minute longer and clocks synchronize.

There's nothing inherently accurate about 60 60 24.

What I cant wrap my head around is the lack of timezones. If I switched to UTC or something based on UTC right now would I be waking up every day at 5 PM? I dont know and I dont much care.

But it seems like there is tension between local/global requirements and right now we favor local because its where we live.

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The point is that at the moment, a day has 86400 SI seconds. If you want to keep it that way, i.e. change neither the length of a day nor change the length of a second, you will have to either divide these 86400 SI seconds up into some sensible pieces (60 60 24, e.g.) or have some remainder left (one day of 10 hours and some weird stuff at the end).

The problem here is not the one-off second, but the length of the second per-se which would have to change. Unfortunately, the length of the second is so deeply tied into the SI system that I’d rather have a non-metric day than a change in the length of seconds.

Timezones are somewhat orthogonal to this, and while there is some advantage to having a global time (‘let’s meet at 17:00, okay?’), local timezones are also somewhat helpful – you can expect shops to open around 8:00 all over the world and wouldn’t expect them to be open at 22:00; similarly, local authorities can change the time (and hence the time when shops open/close, e.g.) without everyone having to reprint their opening times signs (as happens for DST or during WWI/II).

I didnt mean that the second wouldnt have to be redefined at all only that if it was defined in metric, it wouldnt be any more or less prone to adjustment (which I though was the first comments point) than our current system which is inaccurate.

So if our current system still has to be adjusted periodically to fit nature, then what is the real impact of changing the duration of a second? Besides the obvious: breaking every clock on earth LOL

Breaking clocks is boring, but how about breaking SI? We would have to:

  - redefine the speed of light
  - redefine the unit of distance
  - redefine the unit of work 
  - redefine the unit of the electrical current
  - redefine the unit of light flux

The mole, kilogramm and kelvin should be fine, but well. Furthermore, if we wanted to keep a meter the length it currently is, the acceleration due to the gravitation field of the earth would change (currently 9.81 m/s²), along with the kinetic energy of a mass of one kilogram travelling at 1 m/s (currently 1/2 J) and roughly fifty trillion other things.

Really, no. No. NO.

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