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Comment by sn41 | Hacker News Reader

The Sumerians divided the circle into 360 degrees because the Sun's annual path took 360 days to come around a full circle. It's no wonder that 360 degrees feel natural for directions.

Another thing I've encountered: in South India, there is a measure of distance & time called a "nazhika". It is 24 minutes. 2 1/2 nazhika is one hour, 60 nazhikas make a day. A nazhika is also roughly the time taken for a normal person to walk 1 mile. Hence a nazhika is also used as approximately one mile. Seems a bit weird until you remember that light-years involve the same identification of time and distance.

Non-metric units like these and others ("foot") have probably very good reasons behind them, and they could be used by people in their day-to-day activities while not carrying measuring instruments with them. Metric System is more systematic, but people "lose touch" with intuitions of quantity.

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I assume that the Sumerians were observant enough to realize that there were still a few days missing, and that 360 was better because it was a more divisible number actually.

The Sumerians did, in fact, periodically insert intercalary months in order to offset the difference, which suggests that this is in part close approximation and on the other part nice for application.

I did not know this. Thanks.

I feel like unit debates often result from a misunderstanding between sides of "is perfect the enemy of good?" I thought it suspicious that they would have miscounted the days, but you're right: it's so dang useful that it's worth a little error (with occasional corrections) for such convenience.

Of course, at some point it becomes a huge pain and you buckle down and choose something just as arbitrary but easier to handle. And that's why we don't count angles in the milliseconds since 1970. Or days in a year; though we do sometimes measure 3D angles in solid minutes, which seems like a metaphor taken too far :)

How many kiloseconds will you spend working next week?

Even in metric-using countries, nobody uses it for time.

For actual applications of spherical trig though degree, minute, second makes a lot of sense, primarily because the earth rotates about one arc second every 4 minutes, and if you know this then you can do manual navigation via the stars and many other things.

However for many things I do use metric time, just not for the human aspect of it. For example, for one customer (admittedly in the sciences), we had to help them estimate how much hardware they needed for additional load. So you do the work in seconds because at that point the math is easiest, and convert to ratios following.

I for one would love to have metric time. Just today I had to add some durations together to get total duration, which would have been simple thing to do with metric time.

Of course for practical use using SI second wouldn't be very good solution. Traditionally second is derived from the length of day, and I think that would make sense for metric time too. 1 milliday would be somewhat close to 1 minute and 50 millidays (or maybe half deciday) would be close to one hour. Of course the name probably should be something else than "day" to reduce confusion.

So I could be working something like 16 decidays next week.

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