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Comment by abeppu | Hacker News Reader

Does this short page describing a base-10 way of dividing time actually fail to be internally consistent for the few sentences of text describing it?

> A standard hour is broken into 60 minutes. There are 2.4 standard hours in 1 metric hour.

> A metric minute is broken into 100 seconds.

> A standard minute has 60 seconds. There are 2.4 standard minutes in 1 metric minute.

No, a standard minute is 1/1440 of a day, and a metric minute is 1/1000 of a day. There are 1.44 standard minutes in a metric minute.

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I was very confused by this too and finally realized the mistake. The chain of logic went like this:

> There are 2.4 standard hours in 1 metric hour > Therefore there are 240 standard minutes in 1 metric hour > Then divide by 100 to get 2.4 standard minutes per metric minute

Except there aren't 240 standard minutes in 1 metric hour. There's 2.4 * 60 = 144. That the author of the page couldn't keep the conversions straight does not bode well if we were to switch as a society...

I still don't understand how a metric day matches up with a standard day.

I flunked 10th grade math and later dropped out, my brain is having a stroke just reading those graphs.

I reverted back to seconds, which is how I used to use Unix timestamps when I first started with computers. But one day would have 100000 seconds, compared to 86400 seconds in standard time, so how can they both measure a day?

Seconds, minutes and hours in this system are not the same length as the standard versions.

That must be it. I kept watching the two clocks to try and figure out if the second was equal but couldn't. This is the key and should be the first thing you read, seconds not being the same length is a huge detail.

Strange the page does not describe the "metric second" then, since it is not the same as the SI second. I thought that the second was the unit which was the same as in SI (=metric). But then it is not the same as the SI second, so not metric at all. Very confusing.

I feel it's an error to use the same names in the two systems. The values are different, it would be much less confusing to use names that are clearly different too.

A day is a day, Earth rotation defines it. What we can do is decide how long a second is and tweak it to make a day 100k seconds long or 86.4k ones.

If only the length of a day was constant.

It's not, hence leap second corrections to our current earth based imprecise observed solar time based on mean solar days (which are not apparent solar days).

Of course even if it were regular there's that pesky difference in rotation relative to what now??

Sidereal rotation time isn't equal to solar rotation time (mean or apparent).

Time .. less straightforward than most imagine.

> Time .. less straightforward than most imagine.

I think it's more trying to make things which vary fit in a "you shall not vary" square box that is the problem. Technically, this metric/decimal method makes more sense for what we're trying to do, but it's less of a "time" thing than it is a "let's have the same numbers every day so we can agree on when synchronous events need to happen." To _measure_ elapsed time, using a fixed unit such as a second is perfectly fine.

Yea that tripped me up reading too. Something felt like it didn't add up.

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