I understand it might be actually easy for hours, but seconds? Bonus points if you explain how to accurately measure seconds without a clock.
In: Physics
For a long time we’ve known how the length of a pendulum corresponds to the frequency they swing at. So, if we figure out how long a pendulum we need to a period of one second then we can build a clock that uses this pendulum as a reference for how long a second is. [This](https://upload.wikimedia.org/wikipedia/commons/2/29/Anchor_escapement_animation_217x328px.gif) gif shows how the motion of a pendulum can be converted to the ‘ticking’ motion of a clock.
Clocks are, of course, very complicated and there are other mechanisms needed to make a functioning unit. But the pendulum is the core part.
Well, the short answer is they weren’t super accurate at all. Even modern clocks are often a little off from one another, and there’s not too much you can do about that with analog, safe technology. However, “clockwork” mechanisms such as springs and pendulums are able to output stored energy at a remarkably consistent rate, so the deviations in movement between clocks built to the same standard could be kept low enough that you only needed to adjust it every day or so.
As for how to measure seconds without a clock, seconds are based on the decay rate of cesium-133, so by measuring that decay in a sample you can get an extremely precise measure of seconds. Obviously that’s very expensive and potentially dangerous though, so you’re better off just using “one thousands” or “mississippis” like everyone else.
A pendulum would swing and each swing would be a second. There’s be some science involved so the pendulum didn’t stop but that’s was the first second counter. If you electrify quartz it vibrates 32768 times a second. So if you count those oscillations then you have a pretty accurate second.
It’s important to note that we transitioned from using the sun alone to measure time using circles on the ground, then divided that circle by 2 sections of 12. One section for day and one for night at the equinoxes. Each of those 24 segments was then divided into 60 minute (read “small”) divisions. Then divided that division into 60 secondary divisions.
Therefore, seconds are just the smallest reasonable division of measurable time. The length of a second is somewhat arbitrary and is merely based on a division of the original by multiples of 12, which is an easier core number to use geometrically than 10 as it has more divisibles.
The first clocks didn’t accurately measure seconds. If you lived before the 18th century or so, there was not need for much in the way of accurate timekeeping at all.
If you’re a medieval farmer, you need to be at church on Sunday morning, but they ring the bells to let you know when it’s time to head up the hill to the church. Otherwise, you have no firm commitments on your time. Just try to milk your cows in the same 30-minute window every morning.
Accurate timekeeping for your average individual became a necessity with the popularization of trains in the 19th century, because a railroad company needed to say their train would depart Chicago at precisely 11:38 AM. Even then, getting it down to the minute was still a technically impressive feat.
It wasn’t until the 20th century that we needed to measure time on the scale of seconds or smaller. Physicists needed to measure the movements of molecules, GPS systems needed to overcome time dilation due to relativity, race car drivers needed to know which car was 0.05 seconds faster to the finish line.
Even so, how often do you use seconds in your daily life? It doesn’t much matter if your toaster toasts for 87 seconds instead of 90, or if you arrive at a meeting at 10:00:04 instead of 10:00:00. Most of the timekeeping functions in your life could be off by about 5-10 seconds and it wouldn’t make a lick of a difference.
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