Comment on Burning Up
C126@sh.itjust.works 1 month agoTechnically all arbitrary, but Fahrenheit is definitely on a whole different level of arbitrary.
Celsius - 0 = precise freezing point of water and 100 = precise boiling point
Kelvin - same as C, but shifted so 0 is the precise lowest possible temperature
Fahrenheit - 0 is the imprecise freezing point of some random brine mixture, 100 is the imprecise average body temperature of the developer
Rivalarrival@lemmy.today 1 month ago
That’s a myth. It’s no more true than the myth that it was the body temperature of horses, or that the scale was designed to reflect how humans experience the weather. (It happens to reflect how humans experience the weather, but this was an incidental characteristic and not the purpose for which the scale was designed.)
The Fahrenheit scale starts to make sense when you realize he was a geometrists. It turns out that a base-10 system of angular measurement objectively sucks ass, so the developer wasn’t particularly interested in the number “100”, but in geometrically interesting numbers. He put 180 degrees between the freezing and boiling points of water. (212F - 32F = 180F)
After setting the “width” of his degree, he measured down to a repeatable origin point, which happened to be 32 of his degrees below the freezing point of water.
The calibration point wasn’t the “freezing point” of the “random brine mixture”. The brine was water, ice, and ammonium chloride, which together form a frigorific mixture due to the phase change of the water. As the mixture is cooled, it resists getting colder than 0F due to the phase change of the water to ice. As it is warmed, it resists getting warmer than 0F due to the phase change of ice to water. This makes it repeatable, in labs around the world. The stable temperature is the temperature of the brine liquid in which the ice is floating, not the frozen water.
And it wasn’t a “random” brine mixture: it was the coldest and most stable frigorific mixture known to the scientific community.
C126@sh.itjust.works 1 month ago
That was a long way of saying what I said, you just don’t see faranheit as ludicrously out of date, while I (and most of the world) do. Live your life as you wish friend. It’s a random brine mixture. Maybe it was less random back then, but now it’s an arbitrary mixture of water and salts in arbitrary ratios. Deal with it. Fahrenheit sucks.
Rivalarrival@lemmy.today 1 month ago
Every measurement system has had its formal definition changed several times. The kilogram, for example, was once formally defined as the mass of a specific block of metal in France, which was later determined to be losing mass, and thus made a pretty terrible standard. Now, the kilogram is formally defined in terms of the meter and the Planck Constant.
Celsius was once defined by the freezing and boiling points of water, but those aren’t actually constant: Fahrenheit’s brine mixture is actually significantly more consistent. Kelvin’s degree spacing comes from that definition of Celsius, but it it was eventually redefined to be more precise by using the triple point of water: pure water at a specific pressure and temperature where it can simultaneously exist as solid, liquid, and gas. Significantly more accurate, but not enough: Kelvin was redefined in 2019 in terms of joules, which are in turn defined by kg, m, s, which are ultimately defined in terms of the Planck constant.
Celsius is now formally defined in terms of Kelvin. Fahrenheit is also formally defined in terms of Kelvin. Fahrenheit’s brine story is just a piece of trivia.