this post was submitted on 01 May 2025
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Time units are just as cursed as American units.
Conversion between days, hours, minutes and seconds is a total mess. If you never have to do anything with those numbers, you don’t need to worry about it. The moment you need to do calculations or compare devices you run into completely unnecessary problems that would have been easy to avoid. Just think of pumps and fans with units given in l/min or m^3/h.
Just pick the standard time unit and stick with it. Use prefixes to deal with big or small numbers.
This also reminds me of something I realized recently: 24 hours is NOT the amount of time it takes for the Earth to rotate 360°. Because the Earth (assuming North is "up") rotates counterclockwise and orbits counterclockwise, each day is slightly more than 360°, probably close to 361°.
So if we assume a year is about 365.25 days, Earth actually spins 366.25 times. One rotation is just kinda "eaten" by orbiting counterclockwise.
Also known as a sidereal day. Check the animation. It’s pretty cool.
This topic also touches upon the concept of reference frames. When people say that the earth takes 24 h to make a full revolution, it’s in relation to the sun. From a universal perspective, the heliocentric reference frame moves and rotates. From the heliocentric perspective, the usual earth based reference frame also moves and rotates. Nothing is truly stationary, and measuring revolutions is impossible unless you define your frame of reference.
If you say a full revolution takes 24 h, it’s not wrong, but it’s only true in one reference frame.