Rethinking How We Measure Time

The world works in a certain way. We were all taught that as kids, and as adults, we take it for granted. People who question the conventional wisdom are looked at weirdly by the closed-minded.

But if you want to make new things, like building a new product or company, you need to have an open mind and overcome the status quo bias. Question things, boil them down to their first principles, and rebuild them back up from these first principles. Sometimes you’ll end up with a different solution. You should let this process play out with an open mind, without reflexively rejecting anything unconventional, as the unimaginative among us do. This will build your mental muscle.

In this blog post, I want to apply this thinking to how we measure time — the calendar. Why are our units of time — years, months, weeks, days, hours, minutes and seconds — the way they are? Would it be better if they were different? This is a thought experiment — I’m not going to try to convince everyone in the world to change.

First, let’s look at the year. The year is currently the time the earth takes to go around the sun, which is the duration over which one cycle of seasons plays out. Should we change how long a year is? No, because then, summer will be in different months in different years: Jan in some, Feb in some, Nov in some, and so on. You won’t be able to say that January is a good time to vacation in a particular place, or that February is a good time to plant seeds in your farm. This is needless complexity and confusion. So we won’t do anything radical like changing an year to 100 days, or making it 20% shorter or longer. We’ll keep it as it is.

We’ll adjust the year slightly, though. Instead of 365 days, which is close to but not the same as the time the earth takes to orbit the sun, we’ll define the year to exactly match one orbit. This is called the anomalistic year in astronomy, and is approximately 365 1⁄4 days, rather than 365.

Despite its name, it’s actually more regular, because we won’t need leap years any more. An year will always be the same length of time.

Units like the year should stay the same. Imagine going out to buy a kilogram of potatoes and getting less than you expected. When you check, you learn that the kilogram has been redefined to be less than usual on Sundays. That would be stupid. By the same principle, the length of the year should always remain the same. Leap years are irregular. Even what constitutes a leap year is irregular: A leap year occurs whenever the year is a multiple of 4. With an exception: if it’s a multiple of 100, it’s not a leap year. Even the exception has an exception: if the year is a multiple of 400, it’s a leap year.

We’ll eliminate leap years by redefining the year to match the anomalistic year. Then the year will always be the same duration.

What are the implications of making an year 365 1⁄4 days instead of 365? Currently, at midnight on 31 Dec, both the day and year come to an end. In the new calendar, since an year is not a whole number of days, the new year will begin sometime during the day, not at midnight. So the earlier part of the day will be in the last year, and the later part in the next. But I don’t think this will cause too much confusion, since a month is not a whole number of weeks either — the new month arrives partway through the week, so some days in the week fall under the last month, and the rest in the next month. People aren’t confused by that. So they won’t be confused by having a new year arrive partway through a day. It does cause some complexity, but less than that of having leap years, since it’s regular rather than irregular.

Second, the earth orbits the sun in an elliptical path, not a circular one. So it moves closer to and away from the sun. The closest point is called the perihelion. We’ll define the year to start at this instant. Currently, the perihelion arrives on Jan 3 or 4th. Instead, we’ll define Jan 1 to start at the perihelion. This change doesn’t help in a practical sense, but it doesn’t hurt, either, so we might as well make it regular while we’re at it.

Third, let’s look at the day, which is currently the time the earth takes to rotate on its axis. Should we redefine the day? No, because if the day were a different duration of time, the sun would rise at 9 AM on some days, 11 on some, and 5 PM on others, which would be confusing. You won’t be able to play tennis at 7 AM, because that would be early morning on some days, mid-day on others, and midnight on others. So we’ll keep the day at 24 hours.

Fourth, now that we’ve taken care of years and days, let’s look at months. A month is currently roughly the time of the lunar cycle, which is from full moon to full moon. In fact, “month” derives from “moon”. But while that may have made sense in historical times, when we looked up at the night sky to tell the passage of time, we now use clocks and calendars. When was the last time you were invited to a meeting that occurs on the next new moon day? Or booked a flight that takes off on the next full moon day? So, instead of keeping a month in sync with the moon, we’ll have 5 months. Why 5? Because it’s the only factor of 365. Each month will be 73 days. But since the year is now 365 1⁄4 days, the month will be 73.05 days.

This is more regular than some months having 31 days, some 30, some 28, and some 29, which is four different durations! This isn’t how you’d define it if you were building a calendar from scratch, as opposed to accreting hacks over time. So, we’ll make it uniform — all months over the course of a year will be the same duration, and February will be the same in all years.

Since a month is much longer, summer will last only one month, as will spring or monsoon.

Fifth, let’s look at the week, which is currently defined as 7 days, because the Babylonians knew 7 planets. But while that may have had a mystical significance, it no longer does, since we have 8 planets today. And even if we did have 7 planets today, a week should be defined based on practical rather than mystical reasons. Since we use the decimal system, it would be practical to make the week 10 days. This makes it easier to immediately tell which week the 23rd is on. It’s the 3rd week. The first week goes from days 0-9, the second 10-19, the third 20-29, etc. This simplifes things for the same reason that it simplifies calculations to have a kilometer be 1000 meters than say 318.

Sixth, let’s look at the day, which currently has 24 hours, because that’s 12 each for AM and PM. But why 12? Because each of your fingers has three sections, so you can count with 12 with your thumb. But today, since we use clocks, 24 is no longer the best choice. We’ll have 100 hours instead. Why 100? Since we use the decimal system, the day has to be either 10 or 100 hours, and 100 is better, because with 100 hours in a day, an hour would be a short chunk of time, a quarter as long as it is now. So, most things would be on the hour. There would be no need to have a meeting at (say) 9:30. This is necessary today because an hour is too big a chunk of time for scheduling and so needs to be subdivided. But in the new system, with 100 hours in a day, an hour is a much smaller unit of time, so most things will be scheduled on the hour. Such as 39 hours or 40 hours. Minutes won’t need to be used except in rare cases where precision is required. For example if you’re on the way to someone’s house, and they call and ask when you’ll arrive, you’ll just give an answer in hours. Just as we measure our weight in kg and don’t need more precision to use grams, we won’t need more precision than hours much of the time.

Seventh, an hour is currently subdivided into 60 minutes, because the Babylonians and Sumerians used a sexagesimal system. But since we use a decimal system today, we’ll subdivide an hour into 10 minutes, rather than 60. This means that a day will have 100 hours of 10 minutes, for a total of 1000 minutes, rather than 1440, as is the case today. So a minute will be slightly longer than it is today. Which is just as well: even for things in our daily lives that require precision, it doesn’t make a difference whether check-in closes at 9:43 AM or 9:44 AM. This shows that a minute is too small an interval. So making it slightly longer is no loss.

Eighth, a minute is currently subdivided into 60 seconds, , because the Babylonians and Sumerians used a sexagesimal system. But since we use a decimal system today, we’ll subdivide the minute into 100 seconds. This means that a day will 1000 minutes of 100 seconds each, for a total of 100,000 seconds, rather than the 86,400 we have today. So a second will be almost the same duration as today.