3 ms·
isn't a cm now defined based on the distance light travels in a vacuum in a very small period of time? so it's not arbitrary really, or rather it probably goes
by nemomarx 2y ago
isn't a cm now defined based on the distance light travels in a vacuum in a very small period of time?
so it's not arbitrary really, or rather it probably goes the other way around. a cm used to be based on an arbitrary physical distance but was I think redefined to avoid needing to keep a standard meter cube in Paris.
- hnuser123456 2y agoIt started with the grandfather clock. Everyone's clock pendulum needed to be the same length to have the same length of a second. So a meter also happens to (approximately, this was before we could easily be precise to several decimal places) be the length of pendulum that cycles at 0.5 hz (each swing back and fourth is a second) in 9.8 m/s^2 gravity.
- geuis 2y agoIt started with the French. https://en.m.wikipedia.org/wiki/History_of_the_metric_system https://en.m.wikipedia.org/wiki/History_of_the_metric_system The meter was originally based on the measured dimensions of the Earth.
- hnuser123456 2y agoAh yes, you're right. Another nice coincidence that a seconds pendulum is less than 1% away from 1/10 millionth the distance between the equator and poles.
- Calwestjobs 2y agotanach still does not acknowledges science. so does 1/10 millionth error even matter in grand scheme of things ?
- arlort 2y agoI think there were multiple competing suggestions at the time, the grandfather clock was one while the standard ended up being the French proposed one that you mention
- SiempreViernes 2y agoThe standard metre was a rod 1 metre long, you might be thinking of the standard kilo which is a compact cylinder?
- fennecbutt 2y agoWas, they made the smoothest silicon sphere, Avogadro project. And now apparently they define it via physics as mentioned in ops article, "namely a specific transition frequency of the caesium-133 atom, the speed of light, and the Planck constant"