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Comment by jamestomasino | Hacker News Reader

There's a great collection if decimal time ideas, many of which are linked at the bottom of that wikipedia page. I personally always liked the idea of making 1 day into the base unit. Then 0.5 would give you noon, 0.75 is 6pm. It seemed less arbitrary than making a unit into a 10th of a day, since that has no value except in reference to a day.

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Having worked at a software company whose internal date format was indeed based on days as the base unit, I suggest that this is an extremely bad idea. 0.75 may be 6pm, but what is 7pm? 0.7916666666666666 is as close as computers will generally come, but of course it's lossy; try adding increments of an hour and sooner or later you've got an irritating rounding issue.

This is solvable using arbitrary-precision decimal libraries, but relying on one of those for just dealing with general time stuff is a Bad Idea.

I think the idea is that, switching to a decimal system, we would no longer have a use for 7pm - we would just do things at 0.8d

Sure, but trying to persuade billions of people to switch to a new system with unclear benefits and no backwards compatibility is not a recipe for success.

This is basically Julian Day, which astronomers use.

But yes, any humane 'decimal' time system is just optionally giving names to different places in the fractions of a day decimal (I say 'humane' because days have varying lengths, and so should not be used as the basis for a unit used for scientific measures).

I still think naming the fractions might be useful (like 'satoshi').

1/10th of a day is just as arbitrary, maybe less so, then 1/24th of a day.

It's not arbitrary. Check out http://en.wikipedia.org/wiki/Decimal

The only special thing about Decimal and Base 10 is that we have 10 fingers (for the most part, exceptions exist). If we had 12, then 1/24th of a day would make sense, because it would be twice our then-normal Base 12 system. It is evolutionarily arbitrary.

Check this out: http://www.youtube.com/watch?v=-nC8J6YXqdo

base 12 (or 24) and base 60 are actually much nicer to work with mentally than 10.

10 divides by 1 5 and 10 so you can easily figure out halves and tenths thats about it.

12 divides by 1 2 3 4 6 and 12 so you can easily figure out halves, thirds, quarters, sixths, and twelths without much of an issue, less non terminating decimal nastyness.

60 is even better, as it divides by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30 and 60 you get a whole wealth of easy fractions, and easy mental division.

This is probably the reason why a lot of ancient societies had a preference for base 60 and base 12.

you can count to 12 on your fingers aswell, using your individual finger bones on one hand + your thumb as an index.

You can extend this system to count to 60 by using the 5 fingers of your other hand seqentially to represent each set of 12.

http://en.wikipedia.org/wiki/Base_12

http://en.wikipedia.org/wiki/Base_60

I need to add a time period to a time point far far far more often than I need to divide a time period into thirds, quarters, sixths and twelths. And dividing into quarters is not difficult in base 10 either, so you're basically down to chosing between pleasant time arithmetic for our current world or being able to easily divide thirds, sixths and twelths. I'd rather have the nice time arithmetic.

> base 12 (or 24) and base 60 are actually much nicer to work with mentally than 10.

I would say binary is the best base, and perhaps the least arbitrary of all bases since it is the simplest.

EDIT: whoops, bad formatting.

Isn't that what MS Excel does, internally?

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