Universal Calendar

Note: This is ported content from my previous blog. It may appear in a format different than intended. It is also from a version of myself that was younger and dumber. I like to keep this content around for posterity.

Introduction

Today is December 9, 2018, if you’re using the Gregorian calendar. Other calendars exist too, like the Julian and Chinese calendar, however the Gregorian calendar is the most common. The Gregorian calendar has days based off Earth’s rotation, and years are based off how long it takes for the Earth to revolve around the sun. It is a solar based calendar. Every calendar put to use on Earth is either a solar, lunar, or lunisolar calendar. They are all based off the Earth in some way. But that’s a problem. If humans want to become a space-faring race, there will be a lot of confusion when people try to utilize an Earth-like calendar on a planet that takes a different amount of time to rotate and orbit. It would be much simpler to have a universal calendar. A universal calendar would increase in units that would be static across the universe.

To make a good universal calendar, we need to meet four criteria. First, the calendar needs a start date, or a year zero. Next, the calendar needs to have intervals, units which determine how the calendar changes date. Third, the calendar needs to be accurate. Finally, the calendar needs to be convenient.

Start Date

Every calendar needs a start date. The Gregorian calendar started 2018 (almost 2019) years ago, with the birth of Jesus Christ. Well, at least, the period known as Anno Domini did. Before then it was B.C. (Before Christ). With our universal calendar, the best start date for us to use would be the start of the actual universe, the Big Bang. However, that’s not very well defined. If we ever find out the exact starting date of the universe, when everything came to be, then we can use that as the start date of our calendar. Until then, we have to use something that is historically significant but not universal. One of the best start dates of a calendar for a space-faring human race that I can think of is the day a human went into space for the very first time. The first human in space, Yuri Gagarin, went on April 12, 1961. This will be year 0 for our calendar. Although we can’t make this universal, it’s okay because this is static, and everyone will remember when the calendar started.

Intervals

Intervals (the period of time needed for the clock to tick over) do need to be universal, though. This is because intervals are what people will be actively monitoring throughout the universe.

There are two ways we can change the date of the calendar. The first one can be tracked anywhere in the galaxy, but the second would be able to be referenced anywhere in the universe. The first method to create an interval is with the speed of light. We have a black hole in the center of our galaxy,  Sagittarius A*, with a radius of 27,340,332 miles. You can convert this to light-hours by dividing by the time it takes light to travel in an hour (light travels 186,282 miles per second, so multiply this by 360 to get 67,061,520 miles per hour). From this, we find that it takes light 0.40769031 hours to travel the radius of Sagittarius A* (numbers kept as precise as possible to get the most accurate calendar). Now we can just multiply this time frame to make it more similar to an Earth year, by a factor of 20,000 will do. This makes one year of our calendar 0.9307998 Earth years. Using the speed of light to define the interval of our calendar isn’t universal, but we can use this to make an interval that relies on the galaxy, which means every planet in the galaxy can use this calendar. Just make sure to always use the speed of light IN A VACUUM, or else the calendar won’t be accurate.

The speed of light system would be good enough, but it turns out there is a method that is even more universal; half-lives. Certain isotopes of elements decay, and one of the most famous is Carbon-14, used for radiometric dating. Carbon-14 has a half-life of 5,730, give or take 30 years. This is long, so to convert it to around an earth year we will divide it by 15. This makes one half-life year 1.047 earth years. The only problem with this one is that it is not as accurate as the light-speed one, but it is easier to use.

Accuracy

When I mentioned the start date and intervals of our calendar above, I mentioned accuracy a lot. This feature is most important in a universal calendar. A universal calendar can’t be universal if it isn’t exact. The best universal calendar would utilize the start of the universe as the start date and the half life of an isotope as an interval, but we don’t know these values accurately enough to include them in our calendar. The Julian calendar had trouble with accuracy, which is why most places switched to the Gregorian calendar.

Convenience

The final criteria for our universal calendar is that it needs to be easy for everyone to use. The dates need to be manageable numbers, so if we decide to use the start of the universe as our start date we can, but only the last four digits will be in common use because people don’t want to write out all the digits in 14,000,002,018 when writing the date. Also, there needs to be bigger and smaller segments based off our interval, to make it easier to measure. For instance, our system will need its own versions of days and decades, which we can do by multiplying or dividing our year unit by a scale value. It’s important to note that although this is important, it is less important than accuracy.

Our Calendar

Our calendar will use the day the first human launched into space (April 12, 1961) as its start date, and the time it takes light to travel the radius of Sagittarius A* multiplied by 20,000 (0.9307998 earth years), as an interval. We will call this interval “newyears” (I made this up, but what you call it doesn’t matter). For convenience, we need to split our intervals into smaller and larger parts. In the Gregorian Calendar, a year can be split into 365, and each day into 24 hours. A year can also be extended to a decade (10 years), or a century (100 years). Now that we know how our clock will work, we can find what today would be. We are 21,060 Earth days, which is about  57.66 Earth years, away from our start date (21,060 * 365.25 = 57.66). Divide this by 0.9307998 (earth years in a newyear) to find that our start date was 61.95 newyears ago. This is 61 newyears and 345 newdays ago. 345 days into a year with the Gregorian Calendar (20 days from the end) would be December 11. So, today would be December 11, 0061.

Conclusion

These are very rough calculations, but you could see how the universal calendar would work.  You could use other different processes that occur the same way throughout the universe to make a calendar, this is only one example.

So it is possible to make a somewhat universal calendar, but much of the numbers needed to make an true and accurate universal calendar haven’t yet been found to a high enough degree of precision. We can make a calendar based off the half-life of carbon-14 and the age of the universe, but it won’t be accurate enough to have the same date everywhere, which defeats the whole purpose. But a galactic calendar using the time it takes light to travel across Sagittarius A* as a unit of measurement might actually function well. We’ll see if a form of a universal or galactic calendar ever takes off.  

Sources

Calendars Around the World

Title Image: JuralMin on Pixabay

Yuri Gagarin

Sagittarius A*

Light Speed

Carbon-14

• 2025 3
• 2024 1
• 2022 2
• 2020 1
• 2019 2
• 2018 12