We have different metrics internationally for length/distance, weights, temperature, etc. Why, as far as I know, is there only hours/minutes/seconds for the entire world? Not that I’m complaining, the alternative would be a huge pain in the a**, but I’m curious how that happened over time (sorry about the pun). TIA!
In: Physics
There is one official unit system for the world, the SI system with meters, kilogram, seconds, etc, as having different units makes everything pretty difficult.
They have definitions to allow you to derive theses units in the same way everywhere on earth (and basically everywhere in the universe). And if you talk about a length of 1 meter everyone will be able to know what this is exactly.
The only country which does not use these units widespread is the US and basically even the imperial units are derived from SI units (an inch is defined as a specific value in meters, that works similar for the other imperial units too).
There is really only seconds. There were old definitions based on the rotation of the Earth, but that’s surprisingly irregular. The standards were set in the CGPM (metric system) back in the 1960s. In 1967 time was one of the first units converted from an object (the spinning earth) to a physical constant = the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom for which 9,192,631,770 oscillations is the definition of 1 second.
Time is also the most accurately measured unit, a paper in Nature described a measuring device with precision of 1.4 parts in 10^18 , or about one billionth of a billionth of a second.
we have different units of measuring stuff. a piece of wood is the same length regardless of what unit I use to measure it with.
but imagine I come up with different units of time. Those units roll up to days, weeks, months, years, etc. differently than your measure. So now I’m like “can you meet March 2, 1989 at 421:15.6?” and you’re like wtf?
The correct answer probably is that time units are so deeply relevant for our daily lives that nobody wants to get rid of them. Not for a lack of trying, by the way – the french revolutionaries actually tried to establish a decimal time system, but the acceptance was similar to that of Microsoft Teams as a communications platform for software developers. I also remember when the swiss watch maker “Swatch” attempted to establish a non-timezoned “internet time” in the late 1990s that you probably never heard about for the same reason.
Creating a standard for length is easy. Pick some stick. Cut a bunch of other sticks to the same length, and you have a standard. Every culture on earth could do this. Weight and volume are similarly easy.
Precisely measuring time down to the second is much harder. Solar time varies throughout the year, and measuring stars takes more than a second. Mechanical clocks of sufficient precision didn’t show up until the 16th century, well into the age of exploration. This meant one standard was created, and spread to the world before other cultures independently invented their own.
Mostly because of European expansion. Western European nations were very, very interconnected, and these nations, especially England, Portugal, Spain and France set up colonies all over the planet, bringing with them their units of measurement. When modern infrastructure was being set up, such as the telephone system and the Internet, it was largely done by these countries or their colonies, so this became the standard.
Other countries and cultures can and do still use different time measurements. For instance, according to the Hebrew calendar, it’s the year 5784
There are a lot of good answers about how standards are created and why it’s useful to have a single one, but I think your question gets more at the history behind the standard and why different cultures didn’t independently create their own.
The reason for that is that before industrialization there was never much need for a wide-spread standard. If you go back 200-250 years ago nobody was keeping track of time as closely as we do now. They just didn’t need to in their day-to-day life. The overwhelming majority of people everywhere were subsistence farmers. Their lives were dictated by the needs of their animals, the changing of the seasons, and crop cycles. They didn’t care if it was 6AM or 4AM or 8AM. If the sun was up and the rooster crowing, it was time to do work. Likewise, they didn’t need to care how long a minute or hour or second was. There was nothing in their life that was timed so precisely that they needed that information.
It wasn’t until people started working outside the home in factories that regimented time started to become important. That’s when factory owners demanded their workers show up at a specific time and work for a specific amount of time. They started measuring production rates, which required precise time units. This is when the majority of people started caring paying attention to specific units of time like minutes, seconds, and hours.
Standards for units of time spread with industrialization, starting in the UK, then spreading to northern Europe and the US. Then, through them, to imperial possessions around the world. That’s why everyone has the same standard. One wasn’t needed until after most of the world was owned and controlled by European (and US) empires, at which point they all pushed the same standard on everyone else.
Time measurement wasn’t really much of a thing for most people in older times.
But length and weight were VERY important. Tell a farmer that his land is smaller than it is and they’ll get upset. Tell someone that their produce is heavier or lighter will make them really upset. So it is really important for even older civilizations that lengths and weights are somewhat standardized. And being important, there was a lot of attachment to those units as they played important roles in trade.
Whether you woke up and started work “in the period of the wolf” or had dinner “in the hour of the chicken” is much less important for daily life. Your work period varied with the seasons and the length of the day – absolute measures were just not that important. In that sense, standardization didn’t really cause much concern and is more easily adopted. And of course, one really cannot argue with “sunrise” or “noon” or “sundown” as it was pretty obvious to measure and rather independent of who was in charge.
You do see many time measurement systems in history.
Unlike all of the other units of measurement, concepts of days and years are not arbitrary so it’s not surprising that they are almost universally defined identically in history.
The unit of time used to divide a day is arbitrary. A quick search shows that there were a number of different units used by cultures to divide a day. In ancient India, days were divided into 60 or 30 units. In Cambodia, days were divided into 4 units.
Day divisions of 12 come up in ancient Egypt, the middle east, Judaism and China. It’s even used in the 12 hour clock.
I wonder if the consistent divisions of a day into 12 units is not by chance and is related to the number of lunar cycles in a year.
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