It’s always funny to me how worked up people get about the topic. Then when you discuss changing how we measure time, people freak out even more.
Oh, time units are such a mess. Ask anyone who has to design a system with a specific pump in it. You’ve calculated that you need about 345 ml/s, but the pump manufacturer gives you different options l/min, l/h, m^3/h etc.
The French tried to fix the time units too, but apparently the time just wasn’t right for something that radical.
Years and days are fundamental units that you’re kind of stuck with because they’re so fundamental to life on earth. But, even though seconds are SI units, there’s nothing about them that’s special. They’re just a holdover from dividing a day into 24 units, then those units further subdivided by 60 and then another 60.
What’s interesting is that the metric system was invented at a time when being able to convert between units in a way that’s easy for the human brain was important because technology was advanced enough that things could be measured precisely, but wasn’t advanced enough that computers could do the conversion for you.
What’s interesting is that now, before Metric has even caught on worldwide, we’re already past the point of needing easy conversions. The Metric System was important when it was invented because technology had advanced to a point where precision measurement was possible and important, but computers didn’t yet exist. So, converting between miles per hour and feed per second was a pain. But, these days everyone has a smart phone, smart watch, voice assistant, etc. nearby that can easily do the most gnarly conversions with ease.
I’d still like metric time units, but tradition might win over logic now that Apple Watches are so common.
You’re absolutely correct. The second is an arbitrary length of time. If we built a new system today we should probably take the plank time as a basis and multiply it with a suitable number so that the scale is appropriate for humans. It still might not align neatly with days and years, which is a problem, but at least it would be prettier from a physics standpoint.
But then again, how pretty do the units even need to be as long as they’re easy to use. In that sense, second is good enough.
It’s also true that nowadays we have computers that can take care of these calculations, so having quirky units isn’t such a big problem any more. In fact, natural units probably aren’t that annoying now that computers can handle all the heavy lifting for us.
I feel like the time thing is less an issue than other systems because it’s better adopted across the world. Part of where metrication came from is that each country would have their own standard for how long a foot or how big a gallon was, but the months, weeks, days, hours, minutes and seconds are pretty well agreed these days. Most units can be selected arbitrarily without changing much about their usefulness, but with time you want to stick as close as possible to solar days, number of solar days per year, and maybe line up with some seasons/solstices/equinoxes. Changing the sub-divisions of the day also means we’d probably want to re-draw time zones, so we’d want a subdivision that can be reasonably easily divided by something close to 24. I guess you could have a 10 hour day and each hour be 100 minutes, or some such and move to 20 or 25 time zones to keep relatively consistent. A 10 day week doesn’t divide evenly into a year though. The divisors of 365 are 73 and 5, so I guess you could do 10 and have one of the weeks split somewhere, but then you still have to deal with the occasional leap year.
Then there’s the consistency issue, the length of a day varies over time, so regardless of the subdivisions we choose, high precision measurements are going to need to account for that to keep our time in line with the solar day.
You’re definitely right that people can agree on the length of day and year regardless of where they live. This way, there’s no urgent need to change that part of the system.
Since 365ish isn’t a number you can neatly divide with anything, I suggest we just pick some number you like, and then add a leap day when needed. So, let’s say you want to divide the year into 10 decimal months, so let’s call them “donths”. Each donth has exactly 36 days, which means that at the end of the year you still have 5ish days left. It’s not exactly 5, because astrnomy, but don’t worry about it. Then you’ll just lump all the remaining bonus days into an extra donth and you’re done. The length of the first 10 donths is always constant and the length of the leftover extra donth at the end of the year is whatever it happens to be. You could make those days a national holiday when people just wait for the new year to start or whatever.
Decimal time was used for longer workweeks like 7/10, which is counter-productive both in the literal sense and popularity-wise. I wouldn’t adopt a time system that robs me of break days and for all I know 4-day workweek is actually more productive societally.
On top of that, the decimal time system didn’t even stick to a consistent multiplier of 1000. This means that it wasn’t neatly compatible with prefixes, but it was a nice try.